Fotoxx User Guide  v.17.08  best window size ==>


Fotoxx is a free open source Linux application for editing photos and managing a large collection. The goal of Fotoxx is to meet the needs of serious photographers while remaining fast and easy to use. Fotoxx has a rich set of editing, repair, and special effects functions. Image adjustments are displayed instantly in a full-size image, allowing interactive optimization. Fotoxx can be used to manage a large image collection so that finding desired images is fast and easy. Albums can be easily created and arranged. Images can be viewed by clicking location markers on an interactive world map. A detailed list of Fotoxx capabilities is available below.
Hardware Requirements
Fotoxx works best on a strong PC, e.g. 2+ GHz multi-core CPU, 8+ GB RAM. A weaker PC will generally work, but may be slow for some functions and unable to edit large images. A monitor smaller than HD (1920x1080) may feel confining for some functions. The monitor should have accurate color (most do not).
Software Requirements
Most recent releases of popular Linux distributions will work (Debian, Ubuntu, Fedora, Suse, Arch ...). This must be 64-bit Linux. Fotoxx Debian packages are built and tested using Ubuntu. A source tarball and make file is provided to build Fotoxx for Linux flavors that use other package formats or have incompatible libraries.
License and Warranty
Fotoxx is licensed under the GNU General Public License v3. Fotoxx source code is free to use, modify, and share with others. Fotoxx is not warranted for any purpose, but if you find a bug, I will try to fix it.
Origin and Contact
Fotoxx originates from the author's web site:
If you have questions, suggestions, or a bug to report, you may contact me.
The latest source code and install packages (debian format) are available at Fotoxx packages are also available on many other web sites and Linux distributions. Some of these are quite old and should be avoided. It is better to use the above link. If there is a problem, it is easier to fix if you are using the current release.

Fotoxx is updated periodically with new or improved capabilities and bug fixes.
To be notified of new releases, subscribe to the blog (<1 message/month).

Optional Package fotoxx-maps
This is a set of geographic maps covering the world. They show image locations as markers (red dots) that can be clicked to display a corresponding image gallery. Modern cameras with GPS receivers automatically add geotags (earth coordinates) to photos, and these are used by Fotoxx to locate images on a map. Geotags can also be added to images individually or with a batch utility. You can add maps of your own at any scale, and your images will populate the new maps automatically. A source tarball and Debian package are available as described above. If you have a good internet connection, you may not need this package: Fotoxx can also use interactive maps obtained as needed from an internet map service.
Translations of the user interface are available for French, German, Spanish, Catalan, Italian, Portuguese.
If you can help with translations, review the topic Translations.

Fotoxx Capabilities

Table of Contents

Fotoxx Overview
description, prerequisites, license, downloads, capabilities
Fotoxx Usage
    Quick Start 1-page overview document
    User Guide comprehensive Fotoxx usage guide (this document)
    Installation Fotoxx software installation procedure
    Initialization Fotoxx initialization procedure
    Window Views and Menus top-level windows and associated menus
        File View file view window (view image files)
        Gallery View gallery view window (view thumbnails)
        World Map View world map view window (local map files)
        Net Map View net map view window (internet world map)
    File Drag and Drop
file drag and drop methods
    General Image Edit Procedures
overview - how to edit image files
        Edit Workflow
alternative edit methods - simple and complex
        Dialog Mouse Ownership
dialog-mouse control and interaction
        Dialog Completion Buttons
dialog completion options
        Custom Dialog Widgets
how to use custom dialog widgets
        Curve Editing
how to manipulate curves used in edit functions
        Batch Editing
overview of batch editing functions
    Select Images from Galleries
file selection procedure used for many functions
    Menu Shortcuts
popup menus, keyboard shortcuts, favorites menu
    Managing a Large Collection
collection management and image searching
    Right-Click Popup Menus
popup menu functions for file and gallery views
    Keyboard Shortcuts
keyboard shortcuts for file/gallery/map views
    Mouse Functions
mouse functions for file/gallery/map views
    Command Line Parameters
Fotoxx startup options using command line parameters
    Top Panel Status Information
details of information in the file view top panel
File View Menus

    Favorites Menu
graphic popup menu with user-selected functions, icons, and layout
    File Menu

        New Window
start new Fotoxx session in a separate window
        Sync Gallery
open gallery view from current file view image
        Recent Images
open gallery view of most recently seen images
        Newest Images
open gallery view of newest images in the collection
        Open Image File
find and open an image file for viewing or editing
        Open Previous File
open the previous image file
        Open RAW File
open a RAW file for viewing or editing
        New Blank Image
create a new blank image with specified size and color
        Rename Image File
rename an image file
        Copy/Move Image File
copy or move an image file to another directory
        Copy Image File to Desktop
copy an image file to the desktop
        Delete/Trash Image File
delete or trash an image files
        Print Image File
print an image file
        Print Calibrated Image
print an image file using printer color calibration data
        Save to Disk
save an image file (replace, new version, new file name)
    Previous/Next Image Button
show the previous or next image in the current gallery
    Metadata Menu
        View Metadata
list image metadata, short or long form
        Show Captions on Image
show file name, captions, comments in image corner
        Tags Overview
image tags (keywords) used for image searching
        Geotags Overview
image geotags (location data) used for image searching
        Edit Metadata
edit commonly used metadata
            Manage Tags Dialog
manage user-defined tags
            Adding Geotags
add image geotags from user inputs or web service
        Edit Any Metadata
edit any metadata (add, change)
        Delete Metadata
delete specified metadata or all metadata
        Batch Add/Remove Tags
add or remove tags for selected images
        Batch Rename Tags
rename tags for selected or all images
        Batch Add/Change Metadata
add or revise metadata for selected or all images
        Batch Report Metadata
report metadata for selected or all images
        Batch Geotags
add or revise geotags for selected or all images
        Image Locations
list image locations and date groups, click for gallery
        Image Timeline
table of year/month/image counts, click for gallery
        Search Images
search images using any metadata or file name data
    Area Menu

select area - concepts and usage
        Select Area
selecting an image object or area for separate editing
        Find Area Gap
find gap in hand-drawn area outline
        Select Hairy
select a complex area, such as hair or plants
        Area Show/Hide
show or hide area outlines
        Area Enable/Disable
enable or disable an area for editing
        Area Invert
invert an area (exchange outside/inside areas)
        Area Unselect
remove an area
        Area Copy and Paste
copy an area and insert somewhere else later
        Area Open and Save
save an area to a file, open and insert elsewhere later
    Edit Menu

Trim unwanted margins, rotate or level an image
Upright an image rotated 90° or 180°
Automatic 1-click enhancement that may work
Automatic 1-click enhancement that may work
        Retouch Combo
Edit brightness, contrast, color, saturation
        Edit Brightness
Edit brightness distribution, rebalance dark and bright areas
        Zonal Flatten
Increase local contrast to enhance details, brighten dark areas
        Tone Mapping
Increase local contrast to enhance details
        Resize Image
Change the image pixel dimensions
        Flip Image
Mirror an image horizontally or vertically
        Paint Image Mouse-paint with a color, brush size, and opacity
        Clone Image Mouse-paint a copy of one image area over another
        Blend Image Blend or blur image pixels by painting with the mouse
        Add Text
Write text on an image with special effects
        Add Lines/Arrows
Add lines and arrows to an image
        Paint Edits
Paint a retouch function gradually, using the mouse
        Leverage Edits
Apply a retouch function using brightness or color as a regulator
Use another image edit application as a Fotoxx edit function
    Repair Menu

        Sharpen Sharpen a blurred image
Blur an image or image area
Reduce noise (speckles) in low-light images
        Smart Erase
Remove power lines, trash, other small image spoilers
        Red Eyes
Remove red eyes from flash photos
        Paint Transparency
Paint increasing transparency using the mouse
        Add Transparency
Add transparency based on image brightness or color
        Color Mode
Convert to black & white, color, negative, positive, sepia ...
        Color Depth Reduce the number of colors (posterize)
        Shift Colors
Gradually shift RGB colors to GBR or BRG
        Color Saturation
Increase or reduce color saturation (intensity)
        Adjust RGB/CMY
Adjust image colors using RGB or CMY adjustments
        Adjust HSL
Use HSL to select and change image colors
        Brightness Gradient
Add a brightness/color gradient across an image
        Local Color
Fix a false color caste that varies within an image
        Match Colors
Match the colors in one image to those in another image
        Color Profile
Convert color profile (e.g. sRGB <--> Adobe RGB)
        Remove Dust
Remove dust spots on images scanned from old slides
Remove pixelation (jaggies) in low resolution image
        Color Fringes
Reduce chromatic aberation causing color fringes
        Stuck Pixels
Fix bright/dark 'stuck' pixels from camera sensor defects
    Warp Menu

Fix images having curved lines that should be straight
        Fix Perspective
Straighten an object photographed from below or aside
        Warp Area
Warp a selected image area by pulling with the mouse
        Unwarp Closeup
Reverse distortions of a close-up face photo (e.g. big nose)
        Warp Curved
Warp entire image or area using the mouse - curvy warp
        Warp Linear
Warp image by pulling with the mouse - straight lines preserved
        Warp Affine
Warp image by pulling with the mouse - parallel lines preserved
        Flatten Book Page
Flatten and straighten a photographed book page
        Spherical Projection
Curve and image into a sphereoid shape
        Selective Rescale
Rescale image down, leaving selected areas unchanged
        Make Waves
Warp an image with a wave pattern
        Twist Image
Twist an image around a chosen center point
    Effects Menu

Convert a photo into a simulated pencil sketch
Convert a photo to a cartoon-like drawing
        Line Drawing
Convert a photo to a simulated line drawing
        Color Drawing
Convert a photo to a simulated color drawing
        Graduated Blur
Graduated image blur depending on contrast
Convert a photo to a simulated embossing (3D effect)
Convert a photo into simulated square tiles
Convert a photo into a Roy Lichtenstein style dot matrix
Convert a photo into a simulated painting
Change brightness or color radially around a chosen center
Add texture to an image or selected area
Add a background pattern to an image
Create a mosaic using tiles from all available images
        Custom Kernel
Edit and apply a custom convolution kernel to an image
        Directed Blur
Blur an image area in a single direction via mouse drag
        Blur Background
Select foreground areas, blur the background (bokeh, tilt-shift)
        Alien Colors
add random strange colors to an image
    Undo/Redo Button
undo or redo current edit or any edits to current image
    Tools Menu

        Index Image Files
1-shot job to find and index all image files
        User Settings
user settings and preferences
        Keyboard Shortcuts
show and revise keyboard shortcuts for menu functions
        Brightness Graph
show a brightness distribution graph for the current image
        Grid Lines
show or remove grid lines, set line count or spacing
        Line Color
set color for select area outlines
        Show RGB
show RGB values at mouse location or for selected points
        Magnify Image
turn mouse into a magnifying glass over image
        Dark/Bright Pixels
tool to highlight clipping
        Monitor Color
tool to adjust monitor brightness and contrast
        Monitor Gamma
tool to adjust monitor gamma
        Change Language
change the language of the menus and dialogs
        Missing Translations
list missing translations for the current language
        Calibrate Printer
calibrate printer color - compensate for color shifts
        Uninstall Appimage
remove the appimage package completely
show CPU time and current memory usage
    Help Menu
show user guide, recent changes, log file, web site
Gallery View Menu

    Favorites Menu
graphic popup menu with user-selected functions, icons, and layout
    Gallery Menu

        Sync Gallery
open gallery view from current file view image
        All Directories
show all image file directories in a tree structure
        Manage Albums
create and arrange user-defined image collections
        Update Album Files
update albums from updated images
        Replace Album File
exchange an image file in selected albums
        Slide Show
create a slide show with animated transitions and zooms
add bookmarks, view list of bookmarks, go to bookmark
    Gallery View Buttons

        Zoom-in / zoom-out
zoom the gallery thumbnails from zero (text only) to huge
        Sort Gallery
sort gallery by file name, file date or EXIF photo date
        Gallery Scroll Buttons
scroll gallery in pages back or forward, jump to start or end
    Combine Menu

        High Dynamic Range
Combine images for an extended brightness range
        High Depth of Field
Combine images for an extended depth of sharp focus
        Stack / Paint
Combind imges to remove transient cars, tourists, etc
        Stack / Noise
Combine images to reduce noise by averaging
Stitch together a series of images horizontally
        Vertical Panorama
Stitch together a series of images vertically
        PT Panorama
Stitch together a series of images using Panorama Tools
Join many images into a compact table format
Arrange multiple images and formatted text in a layout
    Process Menu

        Batch Convert Files
copy, move, resize, rename, convert, add text ...
        Batch Upright
scan for rotated images and upright them
        Batch Delete/Trash
delete or trash selected images
        Batch RAW
convert RAW files to JPEG/PNG/TIFF, 8 or 16 bit color
        Batch Raw Therapee
convert RAW files to TIFF using Raw Therapee
        Script Files
record edits to a script file, apply script to multiple selected files
        Burn Images to DVD/BRD
create a DVD or BlueRay disc with selected image files
        Find Duplicate Images
search entire collection and find duplicated images
        Export File List
create a list of selected files (e.g. for use in a shell script)
        Export Image Files
export selected files to a directory (e.g. for web upload)
        Batch Add/Remove Tags
add or remove tags for selected images
        Batch Rename Tags
rename tags for selected or all images
        Batch Add/Change Metadata
add or revise metadata for selected or all images
        Batch Report Metadata
report metadata for selected or all images
        Batch Geotags
add or revise geotags for selected or all images
        Image Locations/Dates
list image locations and date groups, click for gallery
        Image Timeline
table of year/month/image counts, click for gallery
        Search Images
search images using any metadata or file name data
World Map Menus
maps using local map files
    Images by Map Location
click on map marker for gallery of images at location
    Choose Map
choose from available maps (USA, France, NYC, etc.)
    Installing Custom Map Files
create and install custom map files
    Set Map Markers
show all map markers or only those for current gallery
Net Map Menus
maps using an internet map source
    Images by Map Location click on map marker for gallery of images at location
    Net Map Source
set web source for map
    Net Map Locations
define or go to named map location (position and scale)
    Set Map Markers show all map markers or only those for current gallery
Other Topics

    Video Files
show and play video clips included in image collection
    Web Service Photo Upload
how to select and upload a batch of images to Flickr, etc.
    Organizing Images for Search
options for image organization and searching
adding or updating a translation
    Recent Changes
list of recent user guide changes
    Technical Notes
some technical information about Fotoxx

Fotoxx Usage

Quick Start

This 1-page document is shown when Fotoxx is started the first time.
It is also available via the menu Help > Quick Start.

User Guide
(this document)
Fotoxx is easy to use but unconventional. To avoid confusion, please read the first few pages of this guide. The rest can be used for reference as needed. The user guide is available in the menu Help > User Guide. When using Fotoxx, press the F1 key at any time to view information for the current or last used menu function.
Fotoxx uses the term directory, which is the equivalent of folder in Windows land. The terms file and image and image file mean a single file of type JPEG, PNG, TIFF, RAW, etc. containing a single image (photo or illustration).

To install Fotoxx, try the appropriate package first: packages. This may work with one click.
If not, you must install from source code. This is not difficult. Instructions are here: tarballs

Fotoxx needs to know where all your image files are located (directory and file names) and their embedded metadata (dates, tags (keywords), geotags, captions, comments, ratings). This data is indexed for fast searching. Fotoxx also creates thumbnail images so that the gallery windows (thumbnail pages) will work fast. Fotoxx does not modify or copy your image files - it only reads them to make the index and thumbnails. These are typically 1-2% as large as the JPEG files from a modern camera.
When Fotoxx starts the first time, you must provide information for the initial file indexing process. Indexing allows for fast image searching and thumbnail gallery paging. Your images are not moved or changed.

top image directories (one or more)

thumbnail directory

Top image Directories
These are the top directories containing your image files, e.g. /home/<user>/Pictures  or similar. Subdirectories underneath your top directories are automatically included, to any depth. Use the [select] button to locate and add your top image directories, one or more. Other files may be mixed with your image files.

This is the directory where thumbnail files will be placed. These are generally less than 2% as large as your image files (30K bytes compared to megabytes). You can use the supplied default or choose another location. Indexing will run faster if this is on a separate physical disk from the image files.

If you have many thousands of images, the initial index function may need significant time. The speed can range from 1000 to 3000 images per minute, depending on computer speed and average image file size. When you add new image files to your collection, the next Fotoxx startup will index only the new images, at this same speed. If there are no new image files, startup will be fast. For more details, see Index Image Files.
Note: You can bypass indexing if you hate this idea (probably misguided, but the customer is always right). See the topics Index Image Files and User Settings. Search and map functions will be disabled if there is no index, and galleries will be slow.
Window Views and Menus 

Use these buttons (window top left) to switch among the viewing modes:

Image File View (key F): the current image file fills the entire window

Gallery View (key G): thumbnail gallery (directory or other image grouping)

World Map View (key W): local maps with clickable markers to display corresponding images

Net Map View (key M): internet maps with clickable markers to display corresponding images

Each view has a row of menu buttons on the left side. These are top-level menus. When clicked, available menu functions are shown in a drop-down list. Hover the mouse over a menu to see popup text with a brief description.
File View (key F)
  +  Zoom an image in/out with the left/right mouse buttons or mouse wheel.
  +  Pan and scroll a zoomed image using a mouse left-drag.
  +  Use the menus (left side buttons) to edit the image and perform utility functions.
  +  The window title bar shows the current image file and directory path.
  +  The top panel above the image shows image and edit status information.
  +  Right-click on image for a popup menu of commonly used functions.
Gallery View (key G)
  +  Use the menus to navigate within the gallery, change the thumbnail size, etc.
  +  Thumbnail size variable from tiny to huge. List view with key metadata.
  +  Click on the directory buttons at the top to go up to higher directories.
  +  Lower directories appear as folder thumbnails in the gallery. Click to go there.
  +  The [TOP] button shows a drop-down list of all top directories. Click to go there.
  +  Click a gallery thumbnail: show the clicked image at full window size (File View).
  +  Right-click a thumbnail for a popup menu of commonly used functions.
World Map View (key W)
  +  Available only if the optional fotoxx-maps package is installed.
  +  The initial map is a very large world map (136 megapixels).
  +  Click anywhere to enlarge that map area to full size.
  +  Left-drag to pan and scroll the enlarged map.
  +  Right-click to collapse the map to fit in the window.
  +  If your image files contain geotags, the map will show corresponding markers
      (geotags come from the camera GPS sensor or can be entered manually).
  +  Click on a marker to get a gallery view of the corresponding images.
  +  You can choose among many supplied maps, and add your own maps.
Net Map View (key M)
  +  A world map from the internet can show any place on earth at any scale.
  +  Markers are present for images with geotags (as described above).
  +  Click on a marker to get a gallery view of the corresponding images.
  +  No extra packages or setups are required - works out of the box.
  +  Needs a fast and reliable internet connection for good response time.

The paragraphs below provide more detail about each of the viewing modes.
File View
The current image file is shown, filling the entire window. Click the arrow button on the left or right side to move to the previous or next image in the gallery. The current image file is a key concept in Fotoxx. This is the file that most of the menu functions will operate on. Other buttons in this view show popup menus which are used to modify the image or perform utility functions.

current view = image file view

change to gallery view

change to world map view

change to Net Map view

favorites - custom popup menu

open, rename, print, delete, trash ...
save, save as new version or new file

open previous or next image file (left or right mouse click)

edit tags, captions, ratings, geotags ... search images

select areas for separate edit, copy, paste

trim, rotate, resize, brightness, color, contrast, add text ...

sharpen, denoise, red eyes, fix color, paint, clone

fix perspective, warp, warp image ...

special effects, arty transforms

undo or redo edit steps (left or right mouse button)

index images, user settings, edit KB shortcuts, magnify ...

help, user guide, change log, edit translations ...

Mouse Actions for Image File View
To zoom the image in the main window, left-click a position on the image. The image will grow with each click and the clicked position will move to the center. A right-click will restore the image to fit within the window. To pan or scroll a zoomed image, left-drag the mouse across the image. The image can move with the mouse or in the opposite direction (like scroll bars), depending on a user setting (menu Tools > User Setings). The movement may be 1:1 with the mouse, or may be magnified for faster movement. The mouse wheel may also be used to zoom the image in or out. The middle mouse button (wheel) will make a zoomed image re-center at the mouse position.
Gallery View
All image files in the current directory are shown as thumbnails. You can scroll through the thumbnails and navigate to other directories. The arrow buttons allow scrolling forward or back. You can also scroll with the mouse wheel or scroll bar. Use the zoom buttons to change the thumbnail size. Clicking on a thumbnail will change to file view and display the image full size. This image is now the "current image". Pressing the gallery button in file view will show the gallery view, with the current image scrolled to the top row. The directory path is shown at the top of the gallery window, with one button per directory level. Click one of the buttons to go to that directory. Its subdirectories will be shown as folder thumbnails. Click one of them to go to that directory. Click the [Top] button to choose another top image directory (if more than one), the root directory ( / ) your home directory (/home/<user>), a gallery of the most recently viewed images, or a gallery of the newest images added to your collection.

change to image file view

current view = gallery view

change to world map view

change to Net Map view

favorites - custom popup menu
sync gallery, albums, slide show

edit bookmarks, go to a bookmark

larger thumbnails

smaller thumbnails

sort gallery images by file name or date

go up to gallery top

go down to gallery end

go up one page

go down one page
combine images: HDR, HDF, stack, panorama, montage, mashup

process - batch move / convert / modify files, search functions

help, user guide, change log, edit translations ...

There are several types of galleries:
  +  Directory: all the image files in a single directory (folder)
  +  Search results: images found by a search function, in various directories
  +  Images in an Album: these may be located in various directories
  +  Recent Files: the most recently viewed or edited images
  +  Newest Files: the images most recently added or modified in the image collection
The gallery window title bar will show the directory name (path), the album name, or Search Results or Recent Files or Newest Files. If the gallery corresponds to a directory, buttons for navigating to parent directories are shown in the top panel. The other gallery types have only the buttons for Album (select an album) and TOP (go to another directory).
If the current gallery is not a directory gallery (e.g. Recent Files), you can navigate to a directory by using the [TOP] button in the navigation bar above the thumbnails.
The [Sort] button is used to sort the thumbnails by file name, file modification date, or photo date (from EXIF data). The displayed date is photo date unless the sort is by file date. Ascending or descending order can be chosen. Albums retain the order they were made with. They cannot be sorted.
A gallery thumbnail has a right-click menu with some commonly used functions. One of these is Popup Image, which creates a popup window with a larger image that can be rapidly zoomed to any size with the mouse wheel. Many popup windows can be open at once. This is useful for comparing multiple photos of the same subject.

Popup Image Manipulation:
  +  Click thumbnail with middle mouse button: popup image appears
  +  Click thumbnail with shift + left mouse button: popup image appears
  +  Mouse scroll wheel: zoom the image bigger or smaller
  +  Key F11: make popup image full screen, or return to prior size
  +  Left mouse button: kill the popup image
  +  Escape key: kill the popup image
World Map View
Initially a world map is displayed. A left click on any area will expand that area to a much larger size, and a right click will return to the whole map view. The mouse wheel also works. Markers are shown where there are images with a corresponding geotag location (from a camera GPS receiver or entered manually into the image EXIF data). The markers can be clicked to show a gallery view of the corresponding images.

change to image file view

change to gallery view

current view = world map

change to Net Map view

choose from available maps (Europe, USA, Germany ...)

set map markers, all images or current gallery only

The Choose Map menu offers a selection of large-scale continental and country maps, and you can also install other maps (countries, cities, parks, etc.). These all work the same way. Markers are shown where there are images with a corresponding geotag location. The markers can be clicked to show a gallery view of the corresponding images. The Markers button allows you to restrict the markers to a subset of images reflected in the current gallery, generated via search and/or album functions.

The initial maps are provided in a separate package: fotoxx-maps. Fotoxx-maps is large - almost 100 MB of maps are provided. You can also add your own maps, explained in the topic Installing Custom Map Files.

Net Map View
This view is similar to the above world map view. The functionality is generally superior, but it depends on having a fast and reliable internet connection. An internet map service is used. Initially a world map is displayed. Use the mouse wheel (or double-click) to zoom-in to any location. Shift the map center using mouse drag. The entire world is represented and can be viewed at any scale down to street-level. You can choose from two map sources, one completely open and one requiring a key (free for normal usage volume). If your internet connection is slow or unreliable, it may be best to use the previous World Map method. This is also the only way to make a custom map.

change to image file view

change to gallery view

change to world map view

current view = Net Map

choose internet map source

set map markers, all images or current gallery only
select named map view (location and zoom level)

File Drag and Drop
Fotoxx accepts drag-drop of image files to F-view or G-view mode. In F-view, the file is opened. In G-view, the result depends on the type of gallery. If the gallery is a directory, the file is added to the directory and the gallery will show the new file in its sorted position, by file name. If the gallery is an album, the file is added to the album in the position where it is dropped. This works also if a text string that is a valid file name is dropped.

General Image Edit Procedures
The image in file view mode (the current image) can be modified with the edit functions in the menus Edit, Repair, Warp, Effects, Combine. These functions modify the current image in memory and as seen in the window. You can use these functions in any order, and the changes are accumulated. When finished editing, use [Save] to save the modified image back to the same file, save to a new file version (e.g. filename.v01.jpg), or input a new file name and/or directory. Image edit dialogs have sliders, spin buttons, or editable curves that immediately update the image. The reaction time depends on the size of the image, the complexity of the function and the speed of your PC. This is typically less than second for most edit functions on a strong PC.
Click the undo/redo button on the left or right side to undo or redo the currently active edit function. After an image has had one or more edits applied, the undo/redo button can be used to go back to prior edit steps or forward to the last edit step. The middle mouse button raises a popup list of all edits done to the current image, and you can select any step to go back to. The image can then be re-edited from this step.

Edit Workflow 
You can minimize the time needed to process many images if you understand the following:
Example Workflow for the initial rotate and trim (crop) of a new batch of photos.
You can process one photo every few seconds (+ think time).
  1.  Copy files from the camera memory card to a directory.
  2.  Open the first file.
  3.  Menu: Edit > Trim/Rotate.
Repeat steps 4-7 for each image. The Trim/Rotate dialog remains open.
  4.  Level the image if needed (drag the right edge).
  5.  Trim the image by dragging the trim borders to suit.
  6.  Press [Save] and choose "new version".
  7.  Press [Next] to edit the next file. Press [Next] again to skip over.

Simple Workflow
Most of the time you can just edit the JPEG file that comes out of the camera. Use the following more complex procedure only if you see "color bands" or "posterization" after editing the image, an indication that JPEG 8-bit color is limiting the image quality.
Complex Workflow
To edit with deep color (more than 8 bits), you can start with RAW files from your camera. There are three options for processing RAW files:
RAW files may have more color depth than 8 bits, especially if the camera is new and very expensive. Conversion into a PNG or TIFF file with 16-bit color will preserve the additional color depth available in the RAW file. The higher color depth reduces the risk of visible color bands when retouch functions are used that can radically shift the brightness distribution. When finished editing, convert the final file to JPEG (quality level 70 or greater) to reduce the file size to 10% or less. Note that editing in deep color is more important than having deep color in the final image. It is very hard to see any difference between a 16-bit TIFF/PNG file and a high quality JPEG made from that same file. To preserve the possibility of re-editing the image later, keep the RAW file, which is smaller than the TIFF or PNG file.

Edit Dialog Mouse Ownership
Some edit dialogs use the mouse to reference or alter the image in the main window. There may be more than one such dialog active at the same time. The mouse is also used to zoom and scroll the image, and you may need to do this while using a dialog. Therefore it is important to understand who owns the mouse (which dialog, or main window) and how to change the ownership:

Edit Dialog completion buttons
mostly work as follows:
    [Proceed] - proceed with lengthy task based on dialog inputs.
    [Apply] - apply settings from dialog to image, leave dialog active.
    [Done] - same as [Apply], but the dialog is closed.
    [Cancel] - discard image changes and close the dialog.

Custom Dial
og Widgets (data input controls)
Non-standard smaller widgets are used to reduce the size of dialogs which can partly cover the image being displayed.
They work almost like the standard Gnome widgets for numeric data entry, text data entry, and buttons.

Curve Editing

Some image edit functions use editable curves. You can manipulate the curves to change some property of the image depending on some other property. The example here shows a brightness curve, whereby you can change brightness depending on brightness (e.g. brighten dark image areas without changing bright areas). Generally, the X-axis of the curve represents the input property (brightness in this example) and the Y-axis the output property (also brightness). The curves can be moved (pulled) with the mouse. "Up" increases the effect and "down" decreases the effect. An anchor point (black dot) is added to the curve wherever it is pulled, and this point remains fixed for subsequent pulls: the curve will continue to go through this point as other parts of the curve are pulled. Anchor points can also be dragged. Delete an anchor point by right-clicking it. 
Batch Editing
There are several batch functions in the Process menu to speed some common tasks.
You can select any number of image files (link) and execute the batch function for all of them.

Batch functions can be used for the following tasks:
Selecting Image Files from Gallery Windows
This procedure is used for all functions that operate on multiple image files (batch add or delete tags, batch convert images, batch RAW convert, manage albums, others). It is explained once here, and this topic is linked from each of the functions using this procedure.

The dialog box is used to select image files. Behind it is a gallery window for the current directory, album, or search results. To select an image, click its thumbnail and the image file will be added to the list in the dialog. Other options are shown below. You can navigate the gallery window to other directories by clicking on the directory names at the top or clicking on thumbnails representing subdirectories. You can choose images from any gallery in any order. The list of image files can also be manipulated to change the sequence or remove images added by mistake. Click on a file in the list to show its thumbnail in the dialog and also set the current list position. The next image file added will be inserted at this position. If the [delete] button is pressed, the current list position will be deleted, and if the [insert] button is pressed, the last deleted image file will be inserted at the current position. The last 100 images deleted are saved and can be re-inserted anywhere: each use of the [insert] button removes one image from the saved list and inserts it at the current position. To move images to a new position in the list: click the image file (its thumbnail will be shown), click [delete]. Repeat to delete more images. Click an image file to set the insert position, then click [insert]. The first deleted image will be inserted before the selected image. Repeat to insert more images from the deleted list. The file list in the dialog can also be edited directly: you can use cut and paste to get the sequence you wish, but be careful to always cut and paste entire lines (complete file names). The [add_all] button will add all the image files in the current gallery. You can select individual images from the gallery, or use [add all] and then delete unwanted images. A single image may also be added multiple times to the list. Image search functions output to a gallery window, and these can be used for selecting images just like a gallery from a physical directory.
Thumbnail click rules:
  +  left click: add the image at the current list position.
  +  right click: remove the image from the list, if present.
  +  Shift + left click: add all images from the last image added up to the clicked image.
       (works in either direction, first to last or last to first)

Menu Shortcuts

The Fotoxx menus are large. You may need time to get used to them and remember where the functions are located. There are three shortcut methods available for frequently used functions:

Managing a Large Image Collection
You can use Fotoxx to manage a huge image collection and still be able to quickly find the images you want. Some effort to organize the images is required. Search methods include directory and file names (or partial names), image dates, image ratings, tags (keywords) (labels for persons, places, objects, events ...), captions and comments, and geotags (location names and latitude/longitude). This is done in a standards-compliant manner so that data can be shared with other image management applications. Options for how to organize a large image collection can be found in the topic Organizing Images.

Right-Click Popup Menus

These menus appear when the image view window or a gallery thumbnail is right-clicked with the mouse. These are the most frequently used functions and are available as popup menus for convenience. Most of these are also contained in one of the left-side main menus for image view and gallery view, as shown above.
 File View popup menu
right click on current image in File View mode to get the following menu
 View Metadata
Show short form metadata report
 Edit Metadata
Edit key metadata items: photo date/time, rating, tags, captions, comments, geotags
 Edit Any Metadata
Edit any metadata item
Change the file name
 Copy/Move to Location
Copy or move the image file to another location
 Copy to Desktop
Copy the image file to the desktop (monitor background)
 Copy to Image Cache
Add the image file to the file cache for later pasting into an album
 Copy to Clipboard
Copy the image file to the clipboard (for other apps to paste)
Upright the image that is turned 90 degrees
Trim (crop) the image, level the image or turn 90 degrees
Resize (rescale) the image width and height
 Voodoo 1 and Voodoo 2
Limited automatic image enhancement, two varieties
 Retouch Combo
Adjust brightness, color, contrast, saturation, black point, white balance
 Edit Brightness
Adjust the brightness distribution (flatten, broaden, change black and white points)
 Zonal Flatten
Enhance contrast and brighten shadows, especially image areas with low contrast
 Tone Mapping
Enhance contrast and apparent brightness range by increasing brightness gradients
 Select Area
Select an image object or area for separate editing
 Show on Net Map
Go to Net Map view, zoom-in to image location (if earth coordinates present)
 Delete/Trash ...
Delete the image file or move it to the wastebasket

 Gallery View popup menu
right click on thumbnail image to get the following menu
 Popup Image
Show image in a larger window - resizable, movable, persistent until canceled.
Zoom in/out using the mouse wheel. When zoomed small it disappears.
Shift + left mouse click on a thumbnail: shortcut for Popup Image.
 View Metadata
Show short form metadata report
 Edit Metadata Edit key metadata items: photo date/time, rating, tags, captions, comments, geotags
 Edit Any Metadata Edit any metadata item
Change the file name
 Copy/Move to Location
Copy or move the image file to another location
 Copy to Desktop
Copy the image file to the desktop (monitor background)
 Copy to Image Cache
Add the image file to the file cache for later pasting into an album
 Copy to Clipboard
Copy the image file to the clipboard (for other apps to paste)
 Upright Upright the image that is turned 90 degrees
 Show on Net Map Go to Net Map view, zoom-in to image location (if earth coordinates present)
 Delete/Trash Delete the image file or move it to the wastebasket

Keyboard Shortcuts

Keyboard shortcuts are available for some functions. The notation "Alt+G" means press and hold the Alt key, then press the G key. Many of these can be changed, and new shortcuts can be added (see KB-shortcuts function).

 F / G / W / M  keys Change view mode: image File, Gallery, World map, Net Map
 F1 function key Display user guide for current or prior function
 F10 function key Toggle main window to full-screen and back. Menu and top panel remain.
 F11 function key
Same as F10, but without menu and top panel. Useful for image viewing.

Image File View

 left/right arrow keys Previous/next image (link)
 + or =  /  - keys Zoom image bigger/smaller (zoom amount adjustable in User Settings)
 Z Toggle: zoom image to 100% / fit image in window
Sync Gallery: set gallery from current image file
 X Magnify Image
 P Open Previous File (or toggle between last two files)
 U Undo current edit, or undo one edit step in the current image
 Shift+U Redo current edit, or redo one edit step in the current image
 N Rename Image File
 K View and edit keyboard shortcuts
 Alt+G Grid Lines on/off (toggle)
 T Trim/Rotate Image
 R Retouch Combo
 Escape key Exit a dialog, exit Slide Show mode
 Space Bar Pause/resume a running slide show

Gallery View

 Home/End keys move to first/last page of image gallery
 Page Up/Down keys move to previous/next page of image gallery
 up/down arrow keys move up/down by one row of image gallery
 left/right arrow keys move to previous/next page of image gallery
 + or =  /  -  keys bigger/smaller thumbnail size
toggle the display of hidden files and directories

Mouse Functions
 Image File View

 left click Zoom-in: magnify image, center at click position
 right click If image is zoomed: restore to window size. If not, popup menu with common functions.
 mouse wheel Zoom image in or out depending on wheel direction
 left drag on image Pan/scroll zoomed image, same direction or magnified opposite direction (like scroll bars)
 mouse + Ctrl key
Mouse acts on main window instead of an active dialog, e.g. Select Area.

 Gallery View

 left click thumbnail
Change to F-view, show full-size image
 right click thumbnail
Show popup menu with common functions
 middle click thumbnail
Pop up a larger image which can be zoomed in or out using the mouse wheel
 scroll mouse wheel
Scroll the gallery page up or down

 World Map View

 left click
If map zoomed small to fit window, zoom map large at clicked location
 right click
Zoom map small to fit window
 left drag
If map is zoomed large, drag map with the mouse
 left click on marker
Change to Gallery View, show all images with geotags at corresponding location
 mouse wheel
Can be used for zooming as described above

 Net Map View

 mouse wheel
Zoom the map in (2x) or out (0.5x)
 left click on marker
Change to Gallery View, show all images with geotags at corresponding location
 left drag
Drag map with the mouse

Command Line Parameters (long and short forms)
 file or directory path

initial image file or directory (gallery) to open
 -album "album name"
initial album (gallery) to open
 -ver  -v
output release version and exit
show a gallery of recently seen image files, most recent at the top
show a gallery of the newest image files (from Index Image Files)
 -prev   -p
show the last file viewed in the previous session
show a blank window
 -lang lc_RC
language code (+ opt. region code) to use for GUI (de, de_AT)
 -menu "func name"  -m
startup menu function - Fotoxx will start with this function active.
 -index N

disable image indexing for faster startup (see below)
 -home /.../fotoxx_home

use an alternate location for user data (instead of /home/<user>/.fotoxx)
-index N  parameter
This command line parameter can be used at Fotoxx startup to partly or completely disable image indexing to obtain a faster startup time. N is 0 or 1 or 2, as explained in the topic User Settings.
the first Fotoxx startup after a reboot may be slow if your image collection is very large. Subsequent startups will be much faster since the image index file is now cached in memory. If you wish to bypass indexing entirely, use  -index 0. Search and map functions will be disabled until you allow the indexing process to complete normally.
-home  parameter
Normally all user data (tag names, bookmarks, albums, favorites ...) is kept in /home/<user>/.fotoxx. The image index file is also here. The command: $ fotoxx -home /some/directory...  will expect all this data to be in the designated directory. This allows you to have multiple image collections that are managed separately. If Fotoxx is started for the first time with a -home parameter, the initial image file indexing process will begin.

Top Panel Status Information

The top panel has status information about Fotoxx and the current image file:
CPU 123%  MB 123  2345x1234x8  3.45MB  56%  edits: 3  blocked  area active  dialog open  busy 45%
CPU 123% current Fotoxx CPU load for all threads (e.g. 200%  ==>  2 CPU cores are fully loaded)
 MB 123
current real memory usage
image width x height x depth (bits per color)
 3.45M image file size (updated when a modified image is saved)
 56% zoom status, image % size
 edits: 3 3 edits have been made and can be reversed with the [undo] button
some menu functions are blocked until the current function is completed
 area active   a select area is present and enabled - edits are confined within the area
 dialog open a dialog is waiting for user input (if not visible, look behind other windows)
 busy 45%
some long running functions show this simple percent completion value

File View Menus

The following are the menus and buttons seen in the File View mode.

Favorites (File View > Favorites)

This is a graphic popup menu which you can populate with your frequently used functions and arrange them on the window using the mouse. An initial popup window (left image) is supplied. Right click an empty space on the window to define a new menu entry. Right click an existing entry to modify it. Use the resulting dialog (right image) to define or change the menu entry. The example above has mostly text menu entries, but the example 'warp' entry was given an icon.
 menu text text for the popup menu - optional if a menu icon is used
 menu func the Fotoxx function to use - the exact menu name
 menu icon menu icon - /directory.../filename.png - optional if a menu text is used
 icon size if an icon is used, its size can be 24x24 to 64x64 pixels
 close window checkbox: option to close the popup window when this menu is selected

Left drag a menu entry to move it somewhere else on the popup window. The popup window can be resized to fit the contained menu entries. Left click a menu entry to select the menu. If "close window" was checked, the popup window will close. All menu settings and icon files are saved in a configuration file whenever the popup window is closed. The configuration file and saved icons are located in the directory:
You can use either the English menu names or their translations for your locale. The menu names must exactly match the Fotoxx menus, but case is not significant. The menu text may include "\n" to represent a newline character.

Icon library: Icons for many image edit functions can be found here:

File Menu (File View > File)
New Window (File View > File > New Window)
Start a new instance of Fotoxx in a new window, slightly offset for visibility. This is useful to compare images or to work with more than one image at a time. Both windows can be used to edit images. The new window will initially have an unmodified version of the current image file. If the same image file is edited in both windows, the final result is the file saved last.

Sync Gallery (Gallery View > Menu > Sync Gallery)
Replace the current gallery (recent files, search results ...) with the directory of the current image file: the image file shown in the File View window.
Recent Images (File View > File > Recently Seen Images)
The 100 most recently seen image files (viewed or edited) are shown in a gallery, from which you can select files to view or edit.
Newest Images (File View > File > Newest Images)
The 1000 most recently added or modified image files are shown in a gallery, from which you can select files to view or edit. You are given a choice of using the EXIF photo date or the file modification date to determine the newest images. If the EXIF date is chosen, image files having no EXIF date are ignored.
Open Image File (File View > File > Open Image File)
This function starts a standard file open dialog, allowing you to select an image file or navigate to another directory and select an image file. The selected file is opened in the Fotoxx main window where you can view or edit the image file using the menus and buttons. The main window title bar always shows the file name and directory of the current image file.

Camera RAW files can also be opened. This may need a few seconds depending on file size and processor speed.  You can proceed to edit the RAW file like any other image file. RAW files are also included in thumbnail galleries, as long as a .jpeg thumbnail image can be extracted from the RAW file (normally true). When saving a RAW file, you must specify a type TIFF or PNG (8- or 16-bit color), or JPEG (8-bit). The RAW file type (file extension) must be included in the list of known RAW file types in Tools > User Settings.
Open Previous File (File View > File > Open Previous File) (Key P)
Go back to the previously opened image file, also if this is in a different directory. This differs from the button [Prev/Next] which goes to the previous or next image file in the current gallery (directory, search results, album). This function retains the current image zoom size and position, which is ideal for rapidly comparing two edited versions of the same image. Zoom-in on the area to compare, and use this function to switch back and forth between the two images.
Open RAW File (rawtherapee) (File View > File > Open RAW (Raw Therapee))
Select and open a RAW camera file using RawTherapee. You can make adjustments to the RAW file such as color temperature, white balance, brightness, color, noise, etc. using Raw Therapee. When the file is saved, a TIFF file is created with 16-bit color depth. This file is now opened in Fotoxx and can be further edited, saved as JPEG, etc. The RAW file type (file extension) must be included in the list of known RAW file types in Tools > User Settings.
New Blank Image (File View > File > New Blank Image)
Create a blank image with specified pixel dimensions and color. This can be used as a background for cutouts taken from other images (via Select Area) and annotation text (via Add Text). Input a file name, choose a background color, and set the desired pixel dimensions. See also the Mashup function.

Rename Image File (File View > File > Rename Image File) (key N) 

This function can automate the process of renaming a series of image files using a root name (e.g. an event or place name) and a sequence number. Open the first image file in the series, input a new name, and press the [apply] button. Use the [next] button to move to the next file if wanted. You can use the same name again by pressing the [previous name] button and then add a suffix or sequence number. Press the [add 1] button to increment the sequence number. A file version number (.vNN) in the previous file name is not copied, and if the file being renamed has a version number, it will be retained.

Copy/Move Image File (File View > File > Copy/Move to Location)

The current file (file view), or the file of a clicked gallery thumbnail (gallery view), is copied to the given location. This location can be entered directly or chosen by a file open dialog if the [browse] button is used. Select the copy option to copy the file and leave the source file in place, creating a duplicate. Select the move option to move the file from the original location to the new location.

Copy Image File to Desktop (File View > File > Copy to Desktop)
The current image file is copied to the desktop (/home/<user>/Desktop).
Delete/Trash Image File (File View > File > Delete/Trash Image File)

The current file (file view), or the file of a clicked gallery thumbnail (gallery view), is deleted or moved to trash, depending on the option selected. Fotoxx uses the Linux desktop standard for trash. If this works, trashed image files go into the standard trash location and can be recovered later if wanted. Otherwise, Fotoxx puts trashed images into a desktop directory named "fotoxx-trash". You can delete it or move it to your Linux-specific trash. If both standard and desktop trash do not work, you must trash the files outside of Fotoxx. If you have multiple files to remove, you can leave the dialog open to avoid opening it for each file selected. If another file is opened, the file name in the dialog updates itself. In gallery view, if another thumbnail is clicked, the dialog updates itself.
Print Image File (File View > File > Print Image)

The print menu brings up a standard Page Setup dialog where you can select a printer, a paper size (letter, A4, etc.), and orientation (portrait or landscape). After using the [apply] button, another dialog starts for entering paper margins and an image scale. The margins can be used to shrink the image or shift it on the page. Image scale can be set in the range 5-100%, where 100% means print the maximum size image that fits within the margins. Smaller values will shrink the image proportionally. The actual print size (image width and height in centimeters) is updated in the dialog as margins and scale are changed, and this can be used to reach a desired printed image size. After the margins dialog, a Print dialog starts for the actual printing. This includes paper type and qality inputs, and a preview of the printed layout which can be accepted or rejected.

Print Calibrated Image  (File View > File > Print Calibrated Image)
This function works like Print Image File described above, but before printing you are asked to supply a calibration file name which is used to adjust image colors prior to printing. The purpose is to compensate for color distortions caused by the printer. See the topic calibrate_printer for details on how to create a calibration file.

Save to Disk (File View > Save)

In the first dialog, select one of the three options: new version, new file name, or replace file.
New Version: Save the current image file with a new version number. File names with version numbers are formatted "filename.vNN.ext" where NN is a version number 01 to 99.  The 4 characters .vNN are inserted between the file name and extension. If the file name has no versions, version .v01 will be created. If file versions are already present on disk, then the next higher version number is used. If the file is a JPEG file, the default quality is used (this value can be set in User Settings). A keyboard shortcut can be assigned to this function if desired.
New File: The 2nd dialog shown above will open to save the current image file to a selected file, which can be the original file, another existing file, or a new file. An edited image file can be saved in formats JPEG, PNG and TIFF. JPEG is normally the best option, since these are compressed to reduce space. You can choose a JPEG quality value in the range 1-100. Lower values give smaller files and less image quality. Values above 70 are generally hard to distinguish from 100 (highest quality, largest file size). PNG files are compressed without any loss of quality and are larger than JPEG files of the highest quality. TIFF files are uncompressed and larger than JPEG or PNG. TIFF and PNG files may be saved with 8 or 16 bits per color. The 16-bit formats only makes sense for files converted from a RAW format having more than 8 bits per color. It is rare that the difference between 8 and 16 bits per color can be seen with the eye. However, an image with higher bits has more latitude when the brightness level or distribution is altered with a program like Fotoxx. PNG-16 files are smaller than TIFF-16 but slower to save due to the compression process. Saving a file as TIFF or PNG can be quite slow for a large image and a slow computer. If an image has transparency information (e.g. a Warp function creates a non-rectangular image shape with transparent peripheral areas), you should save the image as a PNG file if you want the transparent areas to be preserved for some later operation. If you use JPEG, these areas will be black and opaque. JPEG does not support transparency.
If make current is checked, the saved file (new file name) will become the current file. The source file (old file name) remains unchanged. If not checked, the file is saved with the new name, but the current file remains the source file (old name). In either case, the edit history is retained (i.e. Undo and Redo will still work).
Replace: Save the current image file back to itself. If a JPEG file, the default quality is used (this value can be set in User Settings).
File sizes for a 15-megapixel image are roughly as follows (depending on image detail).
The jpeg numbers are the quality value given when the file is saved to disk.
tiff-16 tiff-8 png-16 png-8 jpeg-100 jpeg-90 jpeg-80 jpeg-70
112 MB 38 MB 78 MB 21 MB 8 MB 2 MB 1 MB 0.7 MB
The default JPEG quality is used unless you change the value in the New File dialog. The default value can be set in User Settings (initially 90). You will not be able to see a difference between a file saved with quality 90 and one with 100, but the difference in file space is huge. The Technical Notes section describes potential loss of image quality from repeated open, edit and save of JPEG images. At the default quality of 90 this issue can be generally ignored.

Previous/Next Image Button (File View > Prev/Next)
Keyboard left and right arrow keys
Click with the left or right mouse button to open the previous or next image file in the current gallery. If the current image has unsaved edits, you are warned and given the option to cancel this function. If you proceed, the edits are lost. You must save an edited image before moving to another image. The keyboard left and right arrow keys have the same function.
Directory Jump
If you attempt to go beyond the first or last image in the current gallery (directory), a popup message informs you. If you try again to move in the same direction, the last image file in the next preceding gallery (directory), or the first image file in the next following gallery, will be opened. If there is no preceding or following gallery, or if it has no image files, then nothing is done other than a popup notification. Note that only the next preceding or following directory in the parent directory of the current directory (gallery) is searched. There is no extended search into further directories or subdirectories. If the current gallery is not a directory (e.g. the Newest Images gallery), then there is no preceding or following gallery.

Metadata Menu (File View > Metadata)
Metadata means text data that is stored inside an image file. Digital cameras create some data automatically, such as date and time, technical data about the camera and photo parameters, and location data (if the camera has a GPS receiver). Other data can be added by the user, such as captions, comments, ratings, and tags (keywords that can be used to search images, e.g. persons, places, things, events).

There are several alternatives for organizing a large image collection so that it can be easily searched. It would be good to review these before choosing an organization system.
View Metadata (short) (File View > Metadata > View Metadata (short))
View Metadata (long) (File View > Metadata > View Metadata (long))

The View Metadata functions will display available metadata for the current image file. EXIF metadata contains the date and time of a photo, shutter speed, focal length, pixel dimensions, etc. Digital cameras store this data inside the image. IPTC metadata contains tags (from Fotoxx, Photoshop ...) and captions (frequently found in published images). If an image is edited and then saved, the metadata is updated and stored with the new image. The View Metadata short report outputs the most commonly needed data, including the photo date and time, user-assigned tags and star rating, comments, caption, and a history of Fotoxx edit functions that have been applied to the image. The long report reports all metadata available. The [Extras] button on the short report opens the dialog shown on the right, where you can add extra items to the short report. Any item you see in the long report can be added to the short report. Click an item in the left column to add it to the right column and to the report. Click an item in the right column to remove it. Click the entry "Other Item ..." to type-in any item name not contained in the existing list, which is limited to the most likely needed items.

Fotoxx uses the following EXIF/IPTC data items for image editing and searching:
Key Name Fotoxx data input method
Date/Time Original Edit Metadata function - image date
Keywords Edit Metadata function - image tags
Rating Edit Metadata function - image stars
User Comments Edit Metadata function - comments
Caption-Abstract Edit Metadata function - caption
Geotags Edit Metadata function - location, geocoordinates
Image History
Fotoxx edit functions add to this list
any key Edit Any Metadata, Delete Metadata
There are also several batch functions for entering data into many image files at once. These are described below.
Show Captions on Image (File View > Metadata > Show Captions on Image)
Show the metadata items IPTC Caption and EXIF User Comments at the top of each image displayed. This menu is a toggle switch - the display of captions and comments is set on and off alternatively. If neither is available, nothing is displayed. If only one is available, it is displayed. If both are available, they are displayed on two lines. The lengths are truncated at 200 characters. To see up to 1000 characters, use the View Metadata function. If Show Captions switched ON, captions and comments are also displayed during a Slide Show.
Tags Overview
The Edit Metadata function (below) is used to add tags to an image. Read this overview first.

Image files can have identification or classification tags (keywords, labels) assigned to them. These can be used to search a large image collection for those images having desired tags. Typical tags: the main subject of a photo, the associated event, the location, the persons or things contained, etc. Tags reside inside the image metadata (IPTC:keywords). Tags are normally one word, but a short phrase with imbedded blanks or other delimiters can be used. Commas and semicolons are recognized internally as delimiters (separators) between tags, and therefore cannot be used within a tag. A compound tag like arizona scenery is allowed, but you should use two tags instead for more flexibility: you can search for images having either tag or both tags.

Regardless of the physical organization of your images (directory and file names), tags can be used to create other organizations. All images having a desired tag or tags can be found quickly and displayed in an image gallery window, where you can further review the images and choose those for viewing, editing, or changing their tags. If you have used directory and file names in a meaningful way, you can search for images using these names as well as tags. You can also search images by date, rating, location, and other metadata items. These need not be duplicated in tags. See Search Images below.

Managed Tag System
This is appropriate if you are starting from near nothing and you are able to plan your tag system before adding tags to your images. In this system, you create a limited number of tag categories (e.g. people, places, things, events, holidays, art ...). You then plan the tags or types of tags that will go into each category. Tags are created and assigned to a category as needed during the process of tagging images. An image is tagged by pointing and clicking on the list of available tags, which is organized by category and alphabetically within category. If a new tag is needed, it is created before it can be assigned to an image. The total number of tags should be less than about 500, to keep the list small enough for rapid visual location of tags to click on. Searching images by tags is also done by pointing and clicking on the list of available tags.
managed tag system advantages
+ prevent inconsistent tag names (e.g. landscape, scenery)
+ prevent alternate spellings and typos (e.g. susan, susy, scenery, scenrey)
+ prevent tags that logically include other tags (e.g. landscape, lake)
    (this can be planned and deliberate, but should not happen by accident)
+ searching is reliable because tags do not have the above errors
A large tag list (over 500) slows down the process of tagging images due to the time needed to visually find the tag in the long list (possibly in a scrolled window). This problem is reduced somewhat because a few most recently used tags are shown separately in the edit dialog, where they can be easily seen and chosen. Since a series of photos made at the same time will likely share many tags, adding tags to such a series is made easier and faster.
If tags are broadly defined and fewer in number, search results for tags will be larger, but using the search results (image gallery window) to find a smaller subset of images can be quite fast. Physical file organization is preserved: image files located together in their directories will also appear together in search results.
Images downloaded from the internet often contain tags. These of course have no organization and are collectively chaotic. If you use a managed tag system, it is best to review such images and clean up the tags to conform with your system, or delete them. Whatever tags are present will be automatically added under the category "nocatg". If you notice strange tags in your tag list, use Search Images by tag to find the images needing tag deletion or renaming.
Random Tag System
You may prefer to invent tags as needed with no particular system in mind. Or you may already have thousands of tags, making a conversion to a managed tag system difficult (but not impossible, given a function to mass convert tag names). In this case, you can simply type tags into your images, creating new tags as needed. There is still a limited capability to keep tags organized: existing tags matching the characters you input are shown as soon as there are only a few possible matches. Example: you type "lan" and a list of existing matching tags is shown: landscape, landscapes, Langley ...  If one of these is your intention, you click on it to select the tag. If not, you keep on typing and eventually press Enter to create a new tag. When searching images for tags, you can type desired tag names or pick them from the list of available tags. Available tags matching the first few letters you type are shown, and you can pick from this list. You cannot enter a search tag that does not exist in your images.
Geotags Overview
The Edit Metadata function (below) is used to add geotags to an image. Read this overview first.
Modern cameras can record the location of each photo, using an internal GPS receiver. Latitude, longitude, city or location, and country are recorded in the EXIF metadata of the image JPEG or RAW file. The Edit Metadata function also allows location data to be entered or revised for any image. Locations may also be specified by clicking on a map. There are three functions that can find images for a specified location or region: Search Images: find images by location name (also multiple names and partial matches). Image Locations: find all images for a country, a country and location, or a country, location and date range. Images by Map Location: click on a map to show all images within a range of the clicked location.
Edit Metadata (File View > Metadata > Edit Metadata)
The Edit Metadata function is used to add metadata to an image.
Please read Tags Overview and Geotags Overview (above) before using Edit Metadata.

Edit Metadata is used to edit the most frequently used metadata: image date and time, rating, caption, comments, location data, and tags. The dialog initially shows existing data for the current image. After making additions or changes, press [Apply] to update the image file. There is no automatic file versioning for metadata changes, but if you want a new version, use File Save > New Version before using [Apply].

The dialog shows the metadata for the current image in File View, or for a clicked thumbnail in Gallery View. The dialog updates itself when a new image is opened or new thumbnail is clicked.

Existing tags are shown in Image Tags. Available tags are shown in the Defined Tags window below. One of these tags can be added to the image by clicking it. A tag can be deleted from the image by clicking it in Image Tags. Tags recently added are shown in Recent Tags. This is a convenience to make adding tags to a new batch of images easier, assuming that many of the same tags will be used repeatedly. Point and click the same way.

If the list of defined tags is long, it may be easier to type the desired tag into Enter New Tag. Existing tags matching what you have typed so far will appear in Matching Tags, and you can point and click one of these to add the tag to the image. If the input tag is new (no matching tag is shown), press [Add] when the tag is complete. It will be added to the image and to the list of defined tags under the category "nocatg".

If you are using tag categories, you can select a category, and only those tags will be shown in the list of defined tags. If your tags list is huge, this can reduce the list to a manageable size for pointing and clicking.

The date of the image, if available, is shown as Image Date. This may be entered if missing, or changed. You can enter a full date in the format yyyy-mm-dd or a shorter format yyyy or yyyy-mm. A missing month/day is logically equivalent to 01/01 when used as a low limit for searching, or 12/31 when used as a high limit. The [Prev] button fills-in the date from the previous data entered. This is to allow easy dating of a series of images. If time is important, you can include a time using the format hh:mm[.ss]. You may enter an optional Stars rating for the image.

The [Apply] button writes the data to the image file and to the metadata index file used for searching images.
The [Prev] button can be used to load all available data from the previous image viewed or edited. This can be used to speed-up the processing of a group of images sharing much of the same data.
The [Manage Tags] button starts the Manage Tags dialog.

Manage Tags Dialog

This dialog starts from the button [manage tags] in the Edit Metadata dialog. You can also assign categories to tags to help organize them and locate them more quickly when adding tags to images. They are optional and they play no role in tag searching: only the tag is stored in an image, not its category. Typical categories are people, places, things, events, scenery, buildings, art, etc. To add a new tag with a new category, enter the category and the tag, then click [create]. The category can be left blank and the tag will be assigned to "nocatg". To assign a tag to a different category, click a category (bold text) or enter a new one, click the tag, and press [create]. The tag will move from the old to the new category. To delete a tag, click the tag and press [delete]. Tags used in images but not assigned to a category will appear under "nocatg".

Note: a newly created tag is appended to the end of the tag list for its category. The next time Fotoxx is started, all categories and their tag lists are sorted alphabetically, except that "nocatg" is always last.

Use the [orphan tags] button to list tags that are defined but not assigned to any images. These may be deleted if no use is planned.

Adding Geotags
The Edit Metadata dialog shows the location data for the current image, if any. For an image with missing or incorrect location data, enter a location name (city, park, museum ...) and use the [Find] button to either complete the data in the dialog, or get a list of matching locations to choose from (e.g. London, United Kingdom and London, Canada). The list of locations comes from your image files, so a location will not be known until it is assigned to an image for the first time. Partial matches are found, so you can usually enter a leading substring, e.g. "hono" for Honolulu. Use the [Apply] button to enter the data into the EXIF metadata for the current image, and also into the metadata index file for later searching by location. Use the [Prev] button to fill the dialog data with the last location used. If the [Find] button does not find a location (it is not present in any other image), you can use the [Web] button to find the location data from an internet web service (MapQuest Open for now, but this could change). The location data is completed and returned into the dialog. The web service names are not standardized in format or language, so check the returned data for reasonableness and change the spelling and capitalization if needed. The [Apply] button will add the location data to the image, and this location will be available for future use by the [Find] button. If the [Web] button fails, you can find the location using an internet service, and enter the location data into the dialog.

Here are two web sites to look-up a location/country (there are many others):

Note for non-English locales: If a comma is used for a decimal point in latitude/longitude, this is accepted but converted to a period internally. The web service returns periods.

Blank the latitude and longitude if you want to save only the location and/or country name in the image file. If the latititude/longitude data is changed from the values returned by [Find], the new values are saved for this image file. If a location is saved without latitude/longitude, there will be no location marker on a map, and finding photos for this location by clicking on a map will not work (Images by Map Location). The two other method to find photos by location, Search Images and Image Locations, will still work.

Note: The EXIF keyword "city" is used to mean any location name: city, park, museum, lake, etc. Fotoxx uses the term "location" to avoid confusion (e.g. city = Yellowstone Park). Internally, "location" is converted into "city" for metadata storage or retrieval.

If you change to one of the map views and click on a location, this location will be inserted into the Edit Metadata dialog. If you click within a marker (red dot), the location name and latitude/longitude for that marker will be used. If you click outside a marker, the clicked latitude/longitude will be used, and the location name will not be changed.

If you use the [Find] button to set the dialog location data from a known location, there are two possible outcomes: if there is only one geocoordinate (latitude and longitude) associated with the location, this is returned into the dialog. If there are multiple geocoordinates, the Net Map is shown and zoomed-in to a scale where all markers for all geocoordinates associated with this location are shown. Click within one of the markers to choose the corresponding geocoordinate, or click outside any marker to set a new geocoordinate for this image file. The location name now has a newly associated geocoordinate.

You can use Batch Add Geotags (see below) to quickly add location data to many image files at once.
  +  Enter (or change) a location name (possibly abbreviated) in the dialog.
  +  Use [Find] to find the location and auto-fill country, latitude, longitude.
  +  If there are multiple matches, choose from the list.
  +  If there are too many matches, add more letters or supply the country and try again.
  +  If there are zero matches (not found), try the [Web] button (country is required).
  +  If still not found, add more letters to the location.
  +  If still not found, use one of the above web services and input the data manually.
  +  Use [apply] to update the image file and make the location available for future use.
  +  If there are multiple geocoordinates for a given location and country, click on a map
       marker to select, or click elsewhere to add a new geocoordinate for this location.
Edit Any Metadata (File View > Metadata > Edit Any Metadata)

This is a dialog for editing any metadata for the current image file. The most likely metadata key names are listed. Click one of these to retrieve the current key value. Change the value if wanted and press [Save]. The metadata is updated. To edit a key name not in the list, enter the key name and press keyboard "enter" to retrieve the present value, if any. Then enter or change the value and press [Save]. You may enter the key name in lower case and with or without spaces between the words, e.g. "Bits per Sample" and "bitspersample" will both work. To see all present keys and data, use View Metadata (long).
Delete Metadata (File View > Metadata > Delete Metadata)
Specify the key name to delete, or select All. The metadata is deleted. Use All to clean an image of any identifying information that might be in there. Some keys are not deletable, e.g. File Name.
Batch Add/Remove Tags (File View > Metadata > Batch Add/Remove Tags)

When adding tags to a large number of images having many of the same tags (i.e. the same event or subject), use this function to speed up the process. In the dialog, use the [select files] button to open a gallery window with thumbnail images from which you can select the image files (link).

The dialog shows two lists of tags: those to be added to the selected image files, and those to be removed. Select whether the tags you will enter subsequently are to be added or removed. You can go back and forth as you select tags.

Available tags are shown in the Defined Tags window below. One of these can be added to the currently selected tag list by clicking it. A tag can be deleted from either tag list by clicking it. Tags recently added are shown in Recent Tags. This is a convenience to make adding tags to a new batch of images easier, assuming that many of the same tags will be used repeatedly. Point and click the same way.

If the list of defined tags is long, it may be easier to type the desired tag into Enter New Tag. Existing tags matching what you have typed so far will appear in Matching Tags, and you can point and click one of these to add the tag to the image. If the input tag is new (no matching tag is shown), press [Add] when the tag is complete. It will be added to the selected tag list and to the list of defined tags under the category "nocatg".

If you are using tag categories, you can select a category, and only those tags will be shown in the list of defined tags. If your tags list is huge, this can reduce the list to a manageable size for pointing and clicking.

The [manage tags] button can be used to define tags with categories, as described above in Edit Metadata.

To replace tags, specify the new names in the add tags list and the old names in the remove tags list. To get a list of images having specific tags (which you want to remove or replace), use the Search Images function to find the images, then start this function and use the [select files] button to add all the image files that you just found, or select any subset.

Batch Rename Tags (File View > Metadata > Batch Rename Tags)

With this function, you can rename any number of tags and apply these changes to your entire image collection. Click on a tag to rename from the list of defined tags, enter a new name in the Rename to box, then click on the arrow button to add this pair of names to the list on the right side. Repeat for each tag to rename. If you make a mistake or change your mind, click on the pair of names in the list to remove them. Press [Proceed] when done.
A popup window shows the number of image files containing the affected tag names. Press [Yes] to proceed. The update rate is around 500/minute on a strong computer. The next time Fotoxx is started, the image index function will update all thumbnails for the same images, because the file modification date has changed.
Batch Add/Change Metadata (File View > Metadata > Batch Add/Change Metadata)

This function can revise metadata for multiple image files. You can add new metadata, revise existing metadata, and delete metadata. Use the [select files] button to open a gallery window with thumbnail images from which you can select the image files to be processed (link). Enter metadata key names and values to be assigned, or leave the value blank to delete this key. Press [apply]. You will get a confirmation message and you can proceed or cancel at this time. A list of commonly used key names is provided on the left. Click one of these to insert it into the first empty key name field in the dialog. This list comes from the file
which you can edit to add other keys to the list. The [Full List] button provides information on how to get a list of all available key names.
Batch Report Metadata (File View > Metadata > Batch Report Metadata)

This function can report any metadata for any number of images. The output is a text file which is displayed in the default text editor for your system (e.g. Gedit for a Gnome desktop). You can use the search features of the text editor to find images matching desired metadata, or you can use the text file as input to other programs. Use the [select files] button to open a gallery window with thumbnail images from which you can select the image files to be processed (link). You can navigate through any number of galleries and select any number of image files in each. The [edit] button opens a new dialog (right) where you can select the metadata items to be reported. Click an item in the left column to add it to the right column and to the report. Click an item in the right column to remove it. Click the last item in the left column, "Other Item ...", to type-in any item name not appearing in the list, which contains only the most likely needed items.
Batch Geotags (File View > Metadata > Batch Geotags)

With this function, you can select many images and add the same location data to all of them. Use the [select files] button to select the image files from a gallery window (link). Then get the location data as described above in Edit Metadata, using the buttons [Find] [Web] and [Prev], or one of the map views. Press [proceed] to start the update process. Use this function also to fix inconsistencies in location spellings or latitude/longitude data.
Image Locations (report) (File View > Metadata > Image Locations)

This is a fast way to find all photos made at a given location or location and date range. In the dialog, select the desired level of grouping: by country, by country and location, by country and location and date, or by date and country and location. In the last two cases, you can select a date range for grouping of images having nearby dates. A number N will group images together with dates that are N days or less apart from other images in the group (i.e. gaps are <= N days).

A popup window shows all locations found and the dates of photos taken in those locations. The count of photos taken is also shown. In the above example, 29 photos are from Grindlewald in March 2008. Click on a line in the report to get a thumbnail gallery of those images, and from there you can click on any image to view or edit. Note that this method uses only location and country to find the images. Earth coordinates are not used. If you have images with missing or inconsistent earth coordinates for a given location, use this function to get all of them, and then use Batch Geotags to make the earth coodinats consistent.

Image Timeline (report) (File View > Metadata > Image Timeline)

This report produces a timeline of image counts by month. Click on a year and month in the report to get a thumbnail gallery of all images with a photo date (EXIF) in the selected month. The example here shows 377 images for May 2016.

Search Images (report) (File View > Metadata > Search Images)
Use the Search Images function to find images having any desired metadata. A metadata index file is used for searching, which makes it possible to search thousands of images per second. The index contains a subset of the EXIF and IPTC metadata in the image files. Some of this data is automatic, created by the camera. Other data, such as tags and star ratings, can be added by the user.

There are two report formats: a gallery of thumbnails showing all images that match the search criteria, or a metadata report which combines thumbnails with metadata text. Here is an example of the metadata report format:


The main dialog is on the left. If the button "search other metadata" is used, the dialog on the right appears. This can be used to select metadata that is not available in the main dialog. Details are given below.

In the main dialog, select which images to search, either all (the entire image database) or current set, meaning the images in the current gallery list, which can be a directory, album, or the results of a prior image search. Then choose what to do with the matching images found: new set means replace the current set with the images found, add means add them to the current set (gallery), and remove means remove them from the current set. To remove images, you must search the current set.

Select the desired report type. The gallery report is a page of thumbnail images, as long as needed to hold all the images that match the search criteria. The metadata report has both thumbnail images and a list of metadata items beside each thumbnail. These are some standard items (date, rating, tags, geotags, captions, comments) and any items you added in the optional search metadata dialog.

Enter your search criteria. Select desired tags, dates, star ratings, text (comments, captions), file or directory names, and location names. More details about these are below.

Press the [proceed] button to perform the search. Matching images are displayed in gallery view mode. Choose images to view or edit by clicking the thumbnails. Navigate this set of searched images using the navigation buttons in the gallery view window, or the [Prev/Next] button in the file view window. You can save the searched images as a permanent album, which can be further edited to add or remove images (see Manage Albums).

Available tags are shown in Defined Tags and can be chosen with point and click. If the list of defined tags is long, it may be easier to type the desired tag into Enter Search Tag. Existing tags matching what you have typed so far will appear in Matching Tags, and you can point and click one of these to add the tag to the search list. If you type a tag with no match (it does not exist in any image), the list of matching tags will be empty.

If you are using tag categories, you can select a category, and only those tags will be shown in the list of defined tags. If your tags list is huge, this can reduce the list to a manageable size for pointing and clicking.

A date range may be entered to restrict the search to images within the date range. The format is yyyymmdd. Images are selected which have a date on or after the first date, if present, and on or before the second date, if present. Missing month/day default to 01/01 for the low date limit and to 12/31 for the high date limit. Times may optionally be specified using the format yyyymmddhhmm. Missing times default to 00:00 and 23:59. 

A pair of star ratings may be entered to restrict the results to images having a star rating within the given range. A missing low value implies no stars, and a missing high value means the highest rating, 5 stars.

If last version only is checked, image files with multiple versions will be filtered to include only the last version of each file. This depends on the Fotoxx version naming convention: The original file name is normally filename.ext, and edited versions are filename.v01.ext, filename.v02.ext, etc. If no versions are present, the original file is selected. Otherwise, the last available version is selected. If this convention is not followed, then this option will do nothing.

Image directory and file names may be searched. In the field search files, enter any number of names used for your image directories and file names, separated by blanks. An input of [ egypt cairo ] would match all image directory or file names containing either of these strings. Substrings will also match.
Image comments and captions may be searched. Enter the words to search for in the dialog search text field, separated by blanks. These will be matched to every word in the comments and captions of all images, and matching images are selected. Substrings will also match.

To search locations, enter one or more location or country names in the search locations field. Only image files with geotags matching one of the entered locations will be selected.

The radio buttons all and any apply to tags, text, file names, and locations. You can select images having ALL the entered strings, or ANY of the entered strings. Example: if the location search field is "new york" and "any" is selected, then images located in New Mexico or York, PA would be included. If "all" is selected, then only images located in New York would be selected.

If you wish to find missing data, you can enter "null" as a match value.

Starting with release 17.04, the tag "fotoxx" is automatically added when an image is edited. This enables you to search for edited images by specifying the tag "fotoxx" along with whatever other criteria you need.

Search Metadata Dialog
You may use this dialog to search for "extra" metadata items not present in the main dialog. The items available for any given image file can be shown using View Metadata (long). These include camera make and model, exposure time, F-number, ISO, metering mode, focal length, shooting mode, etc. etc. You can enter shortcut names like "exposuretime" instead of "Exposure Time". You may also enter match criteria, if wanted, so that only the images with matching metadata are reported. For example, if you enter "model" with the match value "DMC-FZ28" (a Panasonic camera) then only the images taken with this camera will be reported.

The matching logic can be selected for each metadata key:
match method
match value(s)
one or more metadata text values to be selected, separated by commas
as above, but any metadata containing these text values will be selected
number =
a single numeric value - equal metadata values will be selected
number =>
a single numeric value - equal or greater metadata values will be selected
number <=
a single numeric value - less or equal metadata values will be selected

If no extra metadata to report is entered, then many thousands of images per second are searched and reported (assuming a strong PC). If extra metadata is entered, the search performance slows to something like 90 images per second. This is because the image files are being read to extract the metadata not included in the metadata index. For good performance, always use dates, file names, etc. to maximize the use of the metadata index and minimize the number of image files that must be read.

There is a separate topic, image organization options, which explains the options for using directory and file names and metadata for image searching.

Album "Search Results"
The output of Search Images is automatically saved in the album Search Results. This is for convenience. You may perform a search and then perform other functions which change the current gallery, replacing the search results. If you need to refer to the previous search, this is instantly available in the album Search Results.

Area Menu (File View > Areas)
Edit functions normally apply to the entire image, but it is possible to edit part of an image (an "area") and leave the rest unchanged. If an image area has been selected, then most edit functions will work only within this area. Some functions ignore a selected area. An area may be selected before starting an edit function, or while an edit function is active. The selected area is immediately active, prior edits are retained, and future edits will apply only within the area. If another edit function is started, the selected area remains active, so it is possible to carry out a series of edits on one area.

"Layers" in Photoshop and Gimp are "areas" in Fotoxx. Instead of selecting something from the image, making a separate layer from the selection, performing edit functions on the layer and finally merging the layers, you select something in the image and perform edit functions on the selection, with WYSIWYG feedback during the edit. Areas can also be saved to a file, opened and pasted into other images, and edited there.
Select Area (File View > Areas > Select)

The Select Area dialog is started with the menu Areas > Select. Select one of the 8 methods (explained below). Each method selects image areas in a different way. You can change methods at any time, and the selected areas are accumulated. An outline of the selected image area(s) is shown as you add or remove areas from the selection. The [Finish] button is used to make the area ready for subsequent image edits within the area. The [Hide] button removes the area outline, giving you better visibility of image edits and area edge blending. Use the [Show] button to show the area outline. The select area dialog can be exited and re-started later to modify an existing area or start a new one.

Line Color
The color used for the mouse selection circle and the area outline can be changed at any time by clicking one of the color buttons. This allows you to maintain good contrast during pixel selection, regardless of the brightness or color.

The following methods are used to enclose one or more image spaces that will belong to the final area. These methods may be used in any sequence to define spaces that are either joined or detached.
 Rectangle  Drag the mouse to enclose a rectangular area.
 Ellipse  Drag the mouse to enclose an elliptical area.
 Freehand Draw    Drag and click the mouse to draw lines that outline an enclosed space.
 Follow Edge   Click or drag along the edge of an image object to draw lines that follow the edge.
 Replace  Drag the mouse near an area edge-line to move the edge to the mouse.
 Select area
 within mouse   
 Left/right drag to select/unselect all pixels within the mouse circle.
 Selection is independent of color.
 Select one matching
 color within mouse
 Click on the image to select a color. Left/right drag to select/unselect pixels
 inside the mouse circle that match the selected color within "match level".
 Select all matching
 colors within mouse
 Left/right drag to select/unselect pixels surrounding the mouse that match
 the color of any pixels inside the mouse circle, within "match level".
 Controls for mouse
 selection methods
 "mouse radius" sets the size of a selection circle around the mouse pointer.
 "match level" sets the color match (0-100%) required for pixel selection.

The following paragraphs explain the details of each method.

Drag the mouse from one corner to the opposite corner of the desired rectangular area to select. A rectangle is drawn to enclose the area. Right-click to delete and start over. Repeat the process to select more rectangular areas.

This works the same as rectangle selection, except that the area enclosed is an ellipse.

Freehand Draw
Drag the mouse (left button down) to draw a freehand (curvy) line, or left-click to connect a straight line from the last point drawn to the point clicked. Continue around the target area until it is surrounded with connected curves and lines. Right click to remove previous lines (mistakes). A right click will remove the previous clicked or dragged line, up to 50 pixels. Right click repeatedly to remove more. A new clicked line will always connect to the end of the previous line. A new dragged line will connect to the previous line if it is started close to the end of that line. If it is started elsewhere, a disconnected line will be drawn. You can start a new drag from far away and draw back to meet the previous line. If a clicked line connects to an undesired point (i.e. you don't want to connect to the last line drawn), right click to erase it and then use drag to start a new sequence of lines. A right-button drag can be used to erase small segments: right-drag closely along a line to erase it, then left-drag to re-draw the line. At the end, an area must be fully enclosed, with no gaps. Lines that overlap a little at the ends are OK. Gaps can be difficult to find and correct, so work at 100% image size or greater and be careful. A series of lines automatically connected with left clicks will not leave gaps, but deviation from this sequence is likely to create gaps. To reduce the possibility of gaps, use deliberate overlaps when manually connecting lines.

Follow Edge
High-contrast pixels (likely object edges) between the last point drawn and a newly clicked position are found and connected. This is effective for clear edges that are not too irregular. Fuzzy and ragged edges may not work well and freehand draw will be needed if high precision is necessary. The rules for connecting lines are the same as explained above. Dragging the mouse instead of clicking works like freehand draw.

Drag the mouse near and along an existing area edge-line. The line will be erased and redrawn at the mouse pointer. This is a faster way to make a small adjustment in an existing line.

Select area within mouse
Left click or drag will select the pixels enclosed by the mouse circle. A right click will unselect the last selection (repeat to unselect more). A right drag will unselect the enclosed pixels.

Select one matching color within mouse
Click on the image to select a color. The color is shown on the color button. You can also use the button to set a color directly. Left/right drag to select/unselect pixels within the mouse circle that match the selected color within match level. Adjust the match level down/up to match more/fewer pixels.

Select all matching colors within mouse
Left/right drag to select/unselect pixels inside the mouse circle. Pixels beyond the mouse circle are also included if they meet these conditions: 1) their color matches any color inside the mouse circle, within the current match level. 2) they are within search range of the mouse pointer. This is a factor of mouse radius, e.g. if mouse radius is 20 and search range is 3, then the search range is 60 pixels from the mouse pointer. Drag the mouse over new areas you want to include. Watch the selected area expand into areas with colors matching those inside the mouse circle. If you go too far, right click to remove the last selection. Repeat if needed to remove more previous selections. Reduce the radius or increase the match level to gain finer control - the selection will expand more slowly and stay closer to the mouse circle. A small radius and high match level can be used to follow along an edge and select pixels up to the edge with good precision. Change to a larger radius and/or lower match level to select larger areas after the fine work is complete. Right drag acts as an unselect: pixels inside the mouse circle and matching pixels within the search range are unselected. If a selection goes too far, it is often easy to correct this by unselecting from outside the selected area. You may need some practice to get a feeling for this and be able to work efficiently.

Mouse Radius and Match Level
These two controls apply only to the select within mouse methods described above. Mouse radius defines the size of a circle around the mouse pointer. Pixels within the circle are selected, or they provide a set of colors for matching and selecting pixels outside the circle. Match level defines a degree of match (0-100%) to select pixels based on their color and brightness. 0 means anything matches, and 100 means a perfect match is required.
  left drag select pixels inside mouse circle and those with matching colors within search range
  right click undo previous selection, repeat to unselect more
  right drag unselect pixels inside mouse circle and those with matching colors within search range
Blend Width
Edits made within an area can be blended with the surrounding image over a distance called blend width. At the edge of the selected area, the image is the original (unedited) image. At a distance of blend width from any edge inside the area, the image is the edited image. For distances in-between, the pixels are a mix of original and edited pixels with a gradual transition. Use the Blend Width control to set the blend width for the current or subsequent edit functions. Zero blend width gives a hard edge to the area edit. Increasing blend width makes the edges of the edit more gradual and harder to distinguish from the original image. Changing the value for the first time after editing an area will cause the edge distance to be calculated for each pixel in the area. This is normally fast (a few seconds), but it may take minutes if the area is large and has a complex geometry (a very long edge). Whenever an area is re-edited or inverted, the edge calculation is discarded and must be repeated if blending is wanted. If the edge of a selected area is within 4 pixels of the image edge, it is no longer considered an edge for blending. If a selected area includes a portion of the image edge, and you do not want blending along this edge (the normal case), be sure the edge of the area is within 4 pixels of the image edge.

Edge Creep
An area that has been finished can be expanded or contracted in 1-pixel steps. The area remains finished, but blend width is no longer valid and must be repeated if needed. This can be helpful to reduce edge effects when an area selected by matching colors is edited in a way that changes its brightness. Selection by color may leave a narrow band of underselected or overselected pixels along an edge where color has become mixed with background. Expanding or contracting the area a pixel or two can produce a cleaner looking edge.

Use [Hide] to hide the area outlines. This is useful when editing the image/area, to better see the effects of the edit without interference from the area outlines. Use [Show] to show the outlines and resume editing the area.


An area is not effective for edits until it is successfully finished. The finish process finds all the areas enclosed by your drawn outlines. When you are finished outlining areas, use the [Finish] button to complete the process. A popup dialog will ask you to click the mouse inside each enclosed area in sequence. The enclosed areas are temporarily colored so you can verify that the final result is what you intended. Press [keep] when all selected areas have been clicked and correctly colored. Press [Undo] if a colored area does not match your intention - the original area outline is restored. If the outline of an enclosed area has a gap, the pixel selection and coloring process will "leak out" and areas outside the enclosure will be colored. In this case, press [Undo] to go back to the original outline. Find the gap in the outline and close it, then try [Finish] again. See the function Find Area Gap below for a fast method to find gaps.

Any enclosed area can be selected, even those not explicitly outlined - if you have a donut with a hole, you can select the donut, the hole, or both.

Areas selected using one of the select within mouse methods are automatically finished whenever you click inside any enclosed area. These areas are mapped during the selection process, whereas areas selected with one of the line drawing methods are mapped only when you click inside them.

If you draw a line from one image side to another, you can click on either side of the line to make an area of all pixels on that side of the line. Example: draw a horizontal line on the boundary between sky and land. Click above the line to select sky, below the line to select land.

Disable the current area and keep the data so that it can be re-activated later. This allows you to alternate edits within a selected area and edits for the entire image.

This function inverts an existing area: the entire image is selected except for the existing area. Using the function two times returns the original selected area. Inverting a selected area invalidates the edge calculation which will be repeated if edge blending is selected.

Discard the current area permanently.

Find Area Gap (File View > Areas > Find Gap)
If an area outline was created by freehand drawing using multiple strokes, it is easy to leave small gaps in the outline that are not visible below 400% zoom. An attempt to finish such an area will fail because the mapping of the interior pixels will leak out through the gap and cover large areas not intended as part of the area. If the Finish functioin fails, use this function to find the gap. Click somewhere on the outline of the failed area. The outline will be re-drawn in one direction from the clicked position, until an "end pixel" is found. This is where the gap is. The function will stop for 2 seconds so you can see where it stopped drawing, and then the entire area outline will display again. If you click again near the same position, the outline will be re-drawn in the opposite direction, again stopping where an "end pixel" is found. Use the freehand draw tool to close the gap, then test again to see if the full outline can be drawn without stopping. This function can be used in parallel with the Select Area function.

Select Hairy (File View > Areas > Select Hairy)


colors to select

colors to deselect
This is an area selection function for complex boundary cases like hair or plants, where selection by color may not work well, and manual selection would be very tedious. The objective is to deselect background pixels, making them transparent, while keeping foreground pixels opaque. The resulting "cutout" can be copied and pasted where needed, without the background.

This function is not very intuitive, and you will likely need practice to become fast and effective.

Follow these steps:
When the area is pasted into the target image, the paste dialog can be used to further blend the edges if needed. The pasted area remains active and can be edited with almost any edit function.
Area Show/Hide (File View > Areas > Show, Hide)
Show or hide the outline of the current area. Hiding the area is useful when the area is being modified with one of the edit functions. This makes it easier to judge the effects of the edit. These are also available as buttons in the Select Area dialog.
Area Enable/Disable (File View > Areas > Enable, Disable)
Disable the current area and keep the data so that it can be re-activated later (Enable menu). This allows you to alternate edits within a selected area and edits for the entire image. These are also available as buttons in the Select Area dialog.
Area Invert (File View > Areas > Invert)
Invert an existing area: the entire image is selected except for the existing area. Using the function two times returns the original selected area. Inverting a selected area invalidates the edge calculation which must be repeated if edge blending is desired. This is also available as a button in the Select Area dialog.
Area Unselect (File View > Areas > Unselect)
Permanently discard the current area. This is also available as a button in the Select Area dialog.

Area Copy and Paste (File View > Areas > Copy Area, Paste Area)
A selected area can be saved to a cache file using the menu Select > Copy Area. This area can be pasted into the same or another image using Select > Paste Area. Click and drag to position the area. The dialog controls can be used to resize, rotate, and change the brightness of the pasted area. The edge blend control allows you to blend the area edges into the background image if wanted.

Area Open and Save (File View > Areas > Open Area File, Save Area File) 
A selected area can be saved to an image file using the menu Save Area File. You are asked to supply a file name. A PNG file is created. The PNG file has an alpha channel (a 4th 'color') for transparency information. The image is a rectangle enclosing the selected area. Selected pixels are opaque, and others are transparent. These files reside in  /home/<user>/.fotoxx/saved_areas  by default, but you can save them anywhere.

Use the menu Open Area File to paste a saved area onto the current image file. The background image will show through the transparent parts of the pasted area. Click and drag to position the area. The dialog controls can be used to resize, rotate, and change the brightness of the pasted area. The edge blend control allows you to blend the area edges into the background image if wanted.

Edit Menu (File View > Edit)
Trim (Crop) and Rotate Image (File View > Edit > Trim/Rotate) (key T) 

This function is used to remove unwanted image margins and/or rotate to upright or level the image.

When the dialog opens, a selection rectangle is placed over the image. The areas outside this rectangle are darkened and represent the parts of the image that will be removed. Drag any side or corner of the rectangle to move that side or corner. The dialog box shows the current width/height ratio of the selection rectangle. If the box lock ratio is checked, then moving a side or corner will also cause another side or corner to move, so that the ratio is maintained. You can also drag from the middle of the rectangle to shift the whole rectangle without changing its dimensions. You can use the width and height spin buttons to adjust the pixel dimensions (or type-in new values), and the selection rectangle will adjust to these.

You can use the keyboard arrow keys to move a side or corner of the selection rectangle in 1-pixel steps. The last side or corner moved with the mouse is the one that is moved with the keyboard.

The [Max] button resets the trim rectangle to the full image size (useful if you want only to rotate the image). The [Invert] button will invert the width/height ratio (e.g. 2.0 to 0.5). The [Prev] button retrieves the width and height values last used for a previous image (useful for setting multiple images to the same size, e.g. to fit a monitor or beamer).

The [Auto] button will automatically set the trim rectangle to omit transparent margins left over from composite and warp functions. These functions leave transparent margins where images did not overlay or were bent away from the edge. [Auto] tries to find a maximum rectangle within these margin areas. This may or may not be the desired margins, so you can keep them or move them with the mouse before committing with the [Done] button.

The six ratio buttons allow you to choose a preset width/height ratio. You can change the ratio button names and the corresponding ratios with the button [customize] which starts a new dialog shown on the right. Enter desired button labels in the first row, and corresponding width/height ratios in the second row (the default names are the same as the ratios, except for "gold"). The [gold] button uses the golden ratio, about 1.62:1. You do not have to keep it.

To level a tilted image, use the mouse to drag the right edge up or down until the image looks level. Use the 90º and 180º buttons to upright an image made with the camera turned. The degrees control can be used to set any angle, -180 to +180 degrees. No resolution is lost with 90 degree rotation. For other angles, the loss of resolution is about 1/2 pixel. The level button can automatically level the image if the camera used provides the needed information (EXIF roll angle).

A left-click on the image will add vertical and horizontal guide lines to help with image leveling. Use right-click to remove them.
Upright (File View > Edit > Upright)

This dialog is a faster way to upright an image that is turned 90 or 180 degrees.
The Upright button will take the correct action automatically if the image EXIF data is correct (normally yes). This function is available in the right-click popup menus for the main image window and gallery thumbnails.
Voodoo 1 (File View > Edit > Voodoo 1)
This is a fast automatic image enhancement with limited capability. This is sometimes effective and "good enough" for rapidly processing many photos. There is no dialog - the modification is simply done when the menu is selected. Reject the change with the [undo] button if desired. The modification consists of a slight flattening of the brightness distribution, an expansion of the brightness range if less than the full range is used, and a slight increase in the color saturation, more for darker areas of the image than brighter areas. The effect is sometimes minimal or even negative.
Voodoo 2
(File View > Edit > Voodoo 2)
This is an alternative automatic enhancement, using the zonal flatten method described below.
Retouch Combo (File View > Edit > Retouch Combo) (key R) 
This function handles all aspects of adjusting image brightness and color: overall brightness and contrast, brightness curves (overall and per color), color saturation, color temperature, white balance and black level.


brightness curves, overall and by RGB color
horizontal line is the neutral value (no change)
This example shows an increase of brightness for
darker image areas, and a decrease for brighter areas.

Use the sliders for brightness and contrast to optimize
the image. This may be adequate for most photos.

To fine tune brightness and contrast, edit the curves
using the mouse.

increases or decreases the effect of the brightness edit curves
moves the entire curve up or down
moves the curve lower and upper parts in opposite directions
low color/high
increases or decreases color saturation
adjusts color temperature (reddish <--> blueish)
dark areas/bright
apply color changes to darker/all/brighter image areas
brightness distribution
show a brightness distribution graph in the curve edit window
click for white balance or black level
enables the mouse to click on a black point or gray/white point
Settings File
dialog settings can be saved in a file and loaded later for use with other images

After making initial adjustments using the sliders, you can fine tune brightness and contrast by editing the curves with the mouse to change which parts of the image have increased or decreased brightness or contrast. The ALL curve adjusts all colors, and the RGB curves adjust individual colors. Use ALL first, then make revisions using RGB.

Dark - Bright image areas
This modifies the operation of the color adjustments to affect primarily darker or brighter image areas. Leave in the middle to adjust all areas equally.

Brightness Distribution
If checked, a brightness distribution graph is drawn inside the curve edit window. The graph is live and changes as the dialog controls are changed. The edit curve overlays the graph and may still be edited.
Click for white balance or black level
If checked, mouse clicks on the image are used to set a black point and/or white balance (otherwise clicks on the image will zoom the image as usual). If you click on a fairly bright gray or white spot on the image, this will be used as a white balance set point, and the image RGB colors will be shifted to make this spot pure gray or white. This is the easiest way to correct a photo with an overall color tint because of bad lighting. You can use the warmer-cooler slider after clicking, and this correction will be added to the prior result. If you click on a very dark spot on the image, this will be used as a black set point, and the image RGB colors will be shifted to make this spot black. This is one way to reduce fogginess in a photo, or make the background night sky look black instead of gray.

Settings File
Load button - load all dialog settings (including the curves) from a file chosen by the user
Save button - save all dialog settings to a file chosen by the user
This can help speed up processing when the same or similar settings can be used for multiple photos made under the same conditions.

Reset - set all controls back to a neutral position - image is also reset
Prev - set all controls to the values used for the previous image
Done - finish the edit, close the dialog, save the control settings
Cancel - cancel the edit, reset the image, close the dialog

You can use the [Prev] button when processing a series of images made under the same lighting and therefore needing the same or nearly the same adjustments.
Edit Brightness Distribution (File View > Edit > Edit Brightness)

With this function you can directly alter the shape of the brightness distribution. Move the sliders and watch the image to find the optimum settings.

Cutoff: If the distribution is low or zero at the dark or bright end, you can stretch the distribution to make it extend more into the dark or bright end, or both.

: This is a fast and easy way to compensate for a common limitation in photos: the brightness range is inadequate, or areas of the image have nearly the same brightness and details are lost. Pixel brightness is redistributed so that each brightness level is more equally represented. Technically, the brightness distribution is made more uniform (flatter). You can flatten any or all three ranges of brightness.

Stretch: The selected low/mid/high brightness region is broadened, which necessarily squeezes adjacent areas. For example, if you broaden the low brightness region, darker areas of the image will have more contrast at the expense of mid- and high brightness areas.

Zonal Flatten (File View > Edit > Zonal Flatten)

Zonal Flatten enhances visible detail in areas having poor contrast. The revised brightness for a pixel is based on the brightness distribution for nearby zones. A larger zones value calculates new pixel values from closer areas. Flatten controls the strength of the effect, and deband moderates darker or brighter image areas. This function can amplify noise in uniform areas like sky. If the deband control is insufficient, use Select Area and Denoise. Alternatively, use Select Area beforehand to select sky (or other areas to omit) and then invert the selection prior to using Zonal Flatten.
Technical Explanation (optional)
The image is divided into area zones according to the input zone count. Each pixel is adjusted based on the 9 closest zones, the 3x3 zones surrounding the zone of the pixel. More zones means smaller and closer zones. The brightness of a pixel is compared to the brightness distributions of the nearby zones, and the brightness is adjusted up or down in the direction that would flatten the distribution if the pixel were really a member of the nearby distributions. The influence of the 9 zones are weighted based on their distance from the pixel being calculated. The influence of the leftmost zones goes to zero for a pixel on the right edge of its zone. The same is true for the topmost zones, etc. This prevents abrupt transitions that could be visible. The nature of human vision hides the radical alterations in pixel brightness, since the eye also judges the brightness of a spot based on its surroundings. A larger number of zones will make each pixel brightness adjustment depend on areas closer to the pixel.
Tone Mapping (File View > Edit > Tone Mapping)

Tone mapping increases the apparent brightness range of an image by increasing local contrast. It is especially useful to improve HDR images, but can also be applied to any image. Tone Mapping increases the contrast between nearby pixels without increasing the overall contrast. It relies on the nature of human vision: contrast within a small angle is perceived more strongly than contrast over a large angle. Tone mapping can bring out subtle details (low contrast) that would otherwise be hard to notice. Other methods can also be used: Retouch Combo can increase the contrast for a selected brightness range (at the expense of others). Flattening the brightness distribution can spread the available contrast (brightness range) more evenly. These methods operate globally: all pixels of a given brightness are processed the same. Tone mapping processes pixels relative to surrounding pixels, and is more effective at enhancing detail and the perceived brightness range. 

In the dialog, the graphic curve determines how much local contrast is increased depending on initial local contrast. The left end of the x-axis corresponds to low-contrast pixels and the right end high-contrast pixels. Raise the left side of the curve to increase the contrast of low-contrast pixels (but this will also enhance low-level noise). The Amplify slider below the curve regulates the internal algorithmic calculation, from no contrast amplification on the left to full amplification on the right. If moved too far to the right, the image may show ugly artifacts, so push it back until these disappear. The curve can be dragged with the mouse and its effect on the image will show up in a second or so (depending on image size and CPU speed). The Amplify slider also needs time to show up in the image. If more contrast is wanted, raise the curve. If uniform areas (e.g. sky) become mottled, pull the left end of the curve down to reduce amplification for low-contrast pixels. In some cases it will be best to select different areas of the image and process them separately, e.g. more conservative for sky, more aggressive for textured surfaces like stone walls and vegitation.
Resize Image (File View > Edit > Resize)  (also called rescale) 

This function resizes the image to a new pixel width and height. You can input the new dimensions directly or choose a percent change. Buttons are present for setting the new size to a simple ratio of the original size. Using one of these will minimize loss of resolution. The [Prev] button recalls the previous size, a convenience if multiple images are being set to the same size. If the lock ratio box is checked, the current width/height ratio will be preserved if either width or height is changed. The change is made immediately, but the image will look the same unless it becomes smaller than the window. The image file size in the top panel is not updated until the modified image is saved.
Flip Image (File View > Edit > Flip) 
Choose either horizontal or vertical flip from the dialog. The image is reversed (mirrored) vertically or horizontally. Repeating the flip restores the original image. Doing both a horizontal and vertical flip is the same as a 180 degree rotation.

Paint Image (File View > Edit > Paint Image)

This function paints over the image with selected colors, using the mouse.

The Paint Color button shows the current color. Click this button to choose a color using the standard Gnome color chooser dialog. You can also shift + left-click on the image to choose a color from the image.

The palette button opens the dialog shown in the middle. Here you can select an image file where you have saved colors for recall. Click on the image to select the color at that position.

The HSL button opens an HSL color chooser shown on the right. This dialog can represent any possible color. Move the sliders to get the color you want, and press Select.

The brush size control sets a circle around the mouse pointer which shows the area being painted or erased. Left drag on the image to paint with the current color. Right drag over a previously painted area to erase (undo the painting). The opacity controls determine how rapidly the color is applied (or erased) at the center and edges of the mouse circle. 100% opacity applies the full color immediately, and a low value allows you to gradually change the color using multiple drags (analogous to spray painting from a distance). Erase also works this way: use 100% opacity to immediately erase, and a low value to erase gradually.

NOTE: zoom the image to 100% or more when using a small brush. If the mouse steps are larger than the image pixels and a small brush is being used, some pixels may be skipped by the mouse and cannot be painted.

If paint over transparent areas is selected, painting over transparent areas will reduce or eliminate the transparency, depending on the opacity controls. If this option is not selected, only opaque areas of the image are painted.

The [undo-last] button reverses the last paint or erase operation, and this can be repeated to remove many recent edits. Each new mouse drag operation is a unit of work that can be separately reversed. The memory for undo is limited, so only the most recent paint and erase steps are kept. [undo all] will put the image back in its initial condition.

You can use the zoom image buttons to zoom the image larger or smaller as needed. If drag image is selected, you can pan or scroll a zoomed image by dragging it with the mouse. This stops the drag from painting or erasing.

If a select area is active, the painting is confined within the area.

Wacom Tablet Operation
You can use a Wacom tablet instead of a mouse. Dragging the stylus in contact with the tablet surface will paint as described above. If one of the stylus buttons is held down while dragging, the operation will be erase instead of paint. You can also set paint or erase mode using the radio buttons in the dialog. Holding down a stylus button is cumbersome, which is why the radio buttons are there. Adding pressure to the stylus will increase the opacity, so you can make lighter and darker strokes without adjusting the opacity controls.

Clone Image (File View > Edit > Clone Image)

This function paints image areas by copying from elsewhere in the image. This method can be used to erase an unwanted object, replacing it with background taken from elsewhere.

Shift + left click on the image to select a source, then drag on the image area to be painted. The source area is painted over the dragged area, immediately or gradually, depending on the opacity settings.

The brush size control sets a circle around the mouse pointer which shows the area being painted or erased. Left drag on the image to paint, or right drag over a previously painted area to erase (undo the painting). The opacity controls determine how quickly the image is modified (or erased) at the center and edges of the circle. 100% opacity paints fully and immediately, whereas a low value allows you to gradually paint using multiple drags. Erase also works this way: use 100% to immediately erase, and a low value to erase gradually.

The [undo-last] button reverses the last paint or erase operation, and this can be repeated to remove many recent edits. Each new mouse drag operation is a unit of work that can be separately reversed. The memory for undo is limited, so only the most recent paint and erase steps are kept. [undo all] will put the image back in its initial condition.

If paint over transparent areas is selected, painting over transparent areas will reduce or eliminate the transparency, depending on the mouse opacity controls and the gradual paint setting. If this option is not selected, image transparency is not changed, and painted areas keep their original transparency values (only the opaque part of the image is painted).

If a select area is active, the painting is confined within the area.

Blend Image (File View > Rdit > Blend Image)

Blend image pixels together (smoothen, blur) by painting with the mouse. The paintbrush radius control sets a circle around the mouse pointer which shows the image area being blended. Left drag to blend, right drag to restore. The strength controls determine how fast the image is blended or restored, at the center and edges of the circle.

If a Select Area is active, only the selected areas are affected.
Add Text to Image (File View > Edit > Add Text)

This function writes text directly on the image. Enter the text into the dialog. Multiple lines can be used. After entering the text, left-click the mouse where you want the text on the image. Click or drag to move the text elsewhere. Right click to remove the text. Use the [Font] button to select a different font. Use the [Size] control to increase or decrease the text size. Use the [Angle] control to change the slant angle of the text. The other controls allow you to provide a background color around the text, a text outline color, and a shadow effect. You can select the color and transparency for all of these. The width control adjusts the width of outlines and shadows. The shadow angle control sets the slant angle of the shadow.

You can initialize the text from any available metadata in the image file. Enter the metadata key (e.g. "user comments") and press [Fetch]. Case and embedded blanks do not matter, so you can abbreviate key names, e.g. "usercomments" instead of "User Comments".

The [Open] and [Save] buttons start a file chooser dialog with which you can load or save all text data from or to a file. All the items in the dialog are loaded or saved, so you can keep a collection of often-used text strings and settings.
The buttons at the bottom work as follows:
Clear the text and metadata fields to blank.
Image with added text replaces (overwrites) the current image file
Image with added text is saved as a new file version
Open the next sequential image file and place the same text at the same position.
Complete the edit and start over. A new text string can now be added to the image.
Complete the edit and exit the dialog. The edited image file must be explicitly saved.
Abandon the edit. Previous use of [Apply] is not reversed.
To add the same text to a series of images: prepare and position the text, press [Replace] or [+Version], then [Next], then [Replace] or [+Version], then [Next] ...
Making a Watermark: See example above. Use a text transparency of 70% or more and a background transparency of 100%. The text should be faint but readable. To add a "relief" effect, use Select Area to put a box around the text and Embossing to give the text an appearance of depth.    
Add Lines/Arrows to Image (File View > Edit > Add Lines)

This function writes lines or arrows directly on the image. Enter a line length and width into the dialog, and select an arrow head if wanted. Left-click the mouse where you want to place it on the image. Drag the ends of the line/arrow to position it on the image. Right click to remove it. The dialog controls allow you to provide a background color, an outline color, and a shadow effect. You can select the color and transparency for all of these. The width control adjusts the width of outlines and shadows. The shadow angle control sets the slant angle of the shadow. The [apply] button makes the current line/arrow permanent, so you can start a new one without leaving the dialog. 

The [Open] and [Save] buttons start a file chooser dialog with which you can load or save all line attributes from or to a file.
Paint Edits (File View > Edit > Paint Edits) 

Use this function in combination with some other edit function. Start an edit function and leave the controls in a neutral position. Then start Paint Edits. Specify a mouse radius and power factors for the mouse center and radius edge. The mouse pointer will be surrounded by a circle with the specified radius. When the mouse is dragged over an area of the image, the current retouch function is applied within the circle. The strength of the function is regulated by the power factors. Typically you will use a high value at the center and zero at the edge, meaning that the strength of the edit will be maximum at the center, changing gradually to zero at the edge of the circle. As you drag the mouse over the same area repeatedly, the edits are slowly accumulated. For example, if the edit function is Retouch Combo, and the brightness curve is moved upward (brighten), then the image will slowly brighten in the area where the mouse is dragged. This is called dodge and burn in some image editors.

Use the [undo] and [redo] buttons to monitor the change, which may be hard to notice at first. Set the center power to 100 to make faster changes (with less fine control). Use a left-button drag to weaken the edit or ultimately erase it. When done using one edit function in one or more image areas, use the [done] button on the edit dialog to complete the edit. Use the [reset area] button on the Paint Edits dialog to erase the active area that is now left over from the mouse dragging. If you leave this area active and start a new edit function, the results may be strange (the new function applies immediately to previously painted areas).

A suggested approach is: (1) start an edit function and leave the controls in a neutral position, (2) start the Paint Edits dialog, (3) drag the mouse over the desired areas and watch the effect, (4) adjust the edit function controls, (5) alternate between the previous two steps. (6) Exit from the edit function, then from Paint Edits.

This method to "paint" edits incrementally can improve selected areas of an image quickly and easily. It works with the following edit functions: Retouch Combo, Zonal Flatten, Tone Mapping, Sharpen, Denoise, Adjust HSL, Color Depth. Others may be added in the future.
Leverage Edits (File View > Edit > Leverage Edits)

It is sometimes effective to apply an edit function "leveraged" by some image attribute, e.g. apply noise reduction to darker areas of the image while leaving brighter areas alone. To do this, use Leverage Edits. Choose brightness or contrast as the lever. This may be for a single RGB color or for all colors. The editable graph controls how subsequent edits are applied to the image. The x-axis is the selected lever, from minimum to maximum value. The y-axis value governs how strongly an edit function affects a pixel having the value on the x-axis. Example: apply tone mapping primarily to dark pixels: Start Tone Mapping, then start start Leverage Edits and drag the curve so that high values are on the left (dark pixels) and low values are in the middle and on the right (bright pixels). You can edit the leverage curve or the tone mapping curve while watching the resulting image.

This function can be used with the same list of edit functions listed in the Paint Edits topic above.
Plugins (File View > Edit > Plugins)

The Plugins menu is on the left. The top entry Edit Plugins leads to the dialog on the right. In this dialog you can define menu names and associated commands for using other image edit programs within Fotoxx. These menus are added to the Plugins menu. The example shown is a menu named "auto-gamma" which starts the command "mogrify -auto-gamma %s" (an ImageMagick function). The "%s" is a placeholder where Fotoxx will insert the name of a temporary copy of the current file in Fotoxx. The called edit program must process the file and replace it with the edited version. Normally this is done by using the program's File > Save menu. Afterwards, you can use the Fotoxx [Undo] and [Redo] buttons to check the results, perform additional edits with Fotoxx, or use [Save] to save the edited image. The image passed by Fotoxx to the external program is a TIFF file with 16 bits per color. Most programs can read this file but may use only 8 bits. When finished using the external program, save the image back to itself using the File > Save menu, and then exit the program. Fotoxx will pick up the revised file and use it as though the edit had been done in Fotoxx. Note that in Gimp you must use the File > Export menu to save the image back to the original input file (File > Save produces an .xcf file).

To add a new plugin, input a menu name and the corresponding command in the Edit Plugins dialog and press the [Add] button. Wherever %s is placed in the command, the file to process will be inserted. Some commands may expect an input and output file to be specified. In this case supply %s in both positions (the output file replaces the input file). You may omit %s if the command does not edit an image file. A warning is given, which you can ignore if this is really your intention.

To modify an existing plugin, select the menu name from the drop-down list. The corresponding command will be shown. Modify the command and press [Add]. You can remove a plugin by selecting it and then pressing the [Remove] button.

A few examples are provided in the initial Fotoxx installation:
Menu Name
command line
gimp %s
mogrify -auto-gamma %s
gthumb %s

The plugin menu is saved in the file  /home/<user>/.fotoxx/plugins  which you can modify with a text editor if desired. This is the only way to change the sequence of the menu entries. Be careful not to screw up the format.

Repair Menu (File View > Repair)
Sharpen Image (File View > Repair > Sharpen)

This function has four methods to sharpen a blurry image.

Unsharp mask
: a fast and effective method also found in other image editing apps.
A technical description can be found via Google.

: steepens brightness transition areas directly, somewhat like tone-mapping.

: small neighborhoods of pixels above, below, left and right of a pixel are compared to each-other. The pixel is given the mean color of the neighborhood with the smallest variance in brightness. This forces pixels on a blurry edge to move to one side of the edge or the other. Edges are made very sharp, but details can be lost.

Median diff: pixel brightness is compared to the median of pixels within radius. The brightness is revised up or down for pixels above or below the neighborhood median. The magnitude of the revision is proportional to the brightness difference and the input values dark and light. The effect is similar to unsharp mask, but the "halo" side-effect is greatly reduced. This method is much slower than the others, especially if a large radius is used. This is because pixel brightness values must be sorted in order to find the median value.

The radius value limits the distance over which pixels around an edge are changed. It should be small for images that are slightly fuzzy and larger for poorer images. Amount controls the strength of the modification. Threshold suppresses changes to low-contrast pixels: a higher values reduces the amplification of low-level irregularities (image noise, uneven skin tones, etc.).

Choose the method, set the parameters, press [apply] and wait a few seconds to see the result. Make changes and repeat the process until satisfied. You can go back and forth among the methods to compare which is best for a given image. Use Select Area to operate on different parts of an image with different methods and parameters.
Blur image (File View > Repair > Blur)
This function can be used to blur or un-sharpen an image. Each pixel is mixed with neighboring pixels to reduce the differences, making edges fuzzy. Enter a value for blur radius and press [apply] to see the results. A small value mixes each pixel with its nearest neighbors and larger values mix more distant pixels. The contribution from each pixel decreases with distance, so the nearest pixels have the greatest contribution. This function is useful to smooth mottled skin tones. You can use select area to limit the blur to a face or part of a face.
Denoise Image (File View > Repair > Denoise)

This function reduces the noise in photos taken under poor lighting conditions, making uniform surfaces appear speckled. It also works for scanned prints, as in the example here. Multiple methods are provided because the best method varies with image noise characteristics. Mixing methods (using one and then another) is often helpful. Choose the method, set the radius or threshold parameter, and press [apply]. Each new [apply] uses the modified image from the previous [apply], so each use will have increasing impact. With a large image, some methods may be slow. To save time, select a small area and experiment with the different methods and settings until you make a decision, then apply the chosen method to the entire image.

The dark areas slider can be used to restrict the process to darker image areas, which are most prone to noise. If left at the right end, all areas are processed. Move it back to the left to process increasingly darker areas only.

Here is a short technical description of each method:
Pixels are compared to the mean and sigma of pixels within a radius.
Those outside one sigma are moved slightly back toward the mean.
 Median Pixels are set to the median value of their neighbors within a radius.
 Top Hat Detect outliers by comparison with surrounding pixels at a distance.
The distance is increased in steps from 1 pixel to the radius limit. Outliers are flattened slightly.
RGB brightness (with noise) is converted into a series of wave functions that
nearly sum to brightness and represent an approximation with less noise.

The wavelets algorithm was adapted from code found in a Gimp plug-in.
The initial version was written by Dave Coffin for the program Dcraw

The [measure] button starts the lower dialog to measure the actual noise level. Move the mouse over the image to show the RGB noise levels within the mouse circle (radius 10, about 300 pixels). This must be a featureless area so that noise is the only variation present. A gray sky is a good source, or a badly out-of-focus image area. To measure camera sensor noise, use a RAW image (JPEG images are processed inside the camera to reduce noise). The graph shows pixel deviations from the regional mean. The solid line corresponds to the mean, and the dotted lines are at brightness levels +5 and -5 from the mean, on a scale of 0-255. The center to edge axis is logarithmic from 0 to 10, with 7 at the midpoint. The numbers at the bottom show the mean RGB brightness and noise levels for the area within the mouse.

More information can be found in the technical notes.
Smart Erase (File View > Repair > Smart Erase)

This function can be used to erase small objects that can spoil a good photo, such as power lines, trash on the ground, a sign, etc. The unwanted object is replaced with pixels taken from the surrounding area. This is sometimes very effective (side-effects almost invisible), and sometimes not. It works best for small or narrow objects in the photo. Radius controls the size of a circle around the mouse pointer, defining the area to select and erase. Drag the mouse to enclose all or part of the object to be removed. Left-drag selects and right-drag un-selects. Press [Erase] to erase the selected area, replacing the pixels with the nearest pixels from outside the selection. If the selection was not precise enough, use [Undo], adjust the selected area, and [Erase] again. Repeated selections and erasures will accumulate until you use [New_Area] to start a new selection. The prior erased areas are now fixed and [Undo] will only work for the current selection. As with all edit functions, the main menu buttons [Undo] and [Redo] can be used to review all changes. It is likely best to work with an image zoomed to 200% or more. The Blur control adds blur to the replacement pixels. This can reduce visible side-effects, since the replacement pixels may be sharper or have more contrast than the surroundings. Change the Blur setting and repeat the [Erase] button. A blur of 0.5 or 1 pixel is usually effective. The [show] and [hide] buttons can be used to show the outline of the current selection or hide it to better judge the results after erasing.
Red Eyes (File View > Repair > Red Eyes)
This function reduces the red-eye effect from electronic flash photos. Two methods are provided. The first is faster but may not handle difficult cases. The second method is more robust but also needs more time and care. To use the first function, left-click on a red-eye one or more times until satisfied. If the darkened area is too small or off-center, do a right-click to undo the change and then left-click more precisely on the center of the red-eye. If a red-eye cannot be fixed correctly, right-click to undo the change and then use the second method. The second method can better handle difficult cases where the red-eye is only slightly red and the color difference with the eyelids is too little for the automatic algorithm to distinguish. Place the cursor over the center of the red eye. Hold the left mouse button and drag the cursor down and to the right. A dotted ellipse will appear enclosing the red eye. Repeat if needed to get the red eye centered in the ellipse (roughly). Note that the shape of the ellipse depends on the direction of the drag, which can allow more precise enclosure of only the red-eye. Left-click inside the ellipse repeatedly while watching the red eye darken, and stop when it is dark enough. If you go too far, the eyelids may start to darken. Right-click to undo and repeat if necessary.
Paint Transparency (File View > Repair > Paint Transparency)
Paint transparent or semi-transparent areas on an image. Such areas are useful in the Fotoxx Mashup function, where images or background underneath a transparent area can show through. Other image editors (e.g. Gimp) can also use transparent areas.

The paintbrush radius control sets a circle around the mouse pointer which shows the area being transformed. Left drag on the image to increase the transparency, right drag to decrease. If gradual paint is checked, the strength controls determine how rapidly the transparency changes at the center and edges of the circle. If gradual paint is not checked, transparency is set to 100% (left drag) or 0% (right drag) for the entire area covered by the mouse circle.

If a Select Area is active, only the selected areas are affected.

An image file having transparency information must be saved as a TIF or PNG file. JPEG files do not support transparency.

Add Transparency (File View > Repair > Add Transparency)

Add transparency to an image based on brightness or a chosen color. Areas of the image with greater brightness, or greater match with the chosen color, will become more transparent. The reverse will happen if Invert Match is checked. Click on the image to set the color to match. You can match based on any combination of hue, saturation, and lightness. Match Level selects the degree of match required for maximum transparency. At the minimum setting (left end), the entire image will be transparent. The Transparency slider regulates the amount of transparency applied (zero at the minimum setting). Threshold sets a match level below which the transparency is zero.
Color Mode (File View > Repair > Color Mode)

Use this function to make a black and white or color negative, or convert a negative image into a positive image, or convert to sepia coloring (for an aged photo effect).

Select one of the buttons:
    reset - return the image to the original state
    black/white positive - convert a color image to black and white
    black/white negative - convert to black and white and invert brightness
    color negative - replace each RGB color with its compliment
    RGB -> GBR - red/green/blue colors are replaced with green/blue/red colors
    sepia - convert to a modified black and white for an aged photo effect

The slider can be used to apply the effect incrementally, from 0% (no change) to 100%.

Each button acts on the current state of the image, e.g. pressing [color negative] twice makes a color positive (i.e. no change from the original).

Color negative: Each RGB color is replaced with the maximum value - the RGB color value. For example, if the RGB colors (% of maximum) are 20/40/60, then the negative color is 80/60/40. Doing this twice brings back the original colors. For pure RGB colors, red becomes cyan, green becomes magenta, and blue becomes yellow.

Color Depth (File View > Repair > Color Depth)
This function changes the normal 16 bits per RGB color (red, green, blue) to any value between 1 and 16 bits per color. At 8 bits per color, there are 16.8 million total color combinations. At 4 bits per color there are only 4096 total colors. Use 1-4 bits for an interesting "poster" effect.
Shift Colors (File View > Repair > Shift Colors)

This function can be used to correct colors or convert an image into false colors. Choose any of the three RGB colors and move the slider left or right from the center. One of the two other colors will be substituted in a graduated manner. For example, you can gradually substitute green or blue for the color red. The All slider shifts all colors together. Do this first to find a first optimum, then shift the RGB colors individually.

Color Saturation (File View > Repair > Color Saturation
There is one slider control to adjust color intensity or saturation from zero (black and white image) to 100%.
Retouch Combo also includes an adjustment for color intensity.
Adjust RGB/CMY (File View > Repair > Adjust RGB/CMY)

This function is used to change overall brightness and contrast, or that of selected colors. The settings are retained within and across Fotoxx sessions, so this function can be used to process multiple photos made under the same lighting conditions and needing the same (or nearly) adjustments. Use the [reset] button to restore all inputs to neutral values.
 Brightness  Increase or decrease overall image brightness
+Red - Cyan  etc.
 Increase or decrease the brightness of one color
 and change complimentary color in the opposite direction
 Increase or decrease the overall image contrast
 Red, etc.
 Increase or decrease the contrast of individual RGB colors
Adjust HSL
(File View > Repair > Adjust HSL)

Change a selected range of colors in an image using an HSL color chooser (Hue, Saturation, Lightness). This function can be used to fix color problems, e.g. a false color cast in the entire image or in certain colors, or an overexposed sky (too white). If you are not familiar with the HSL color model, I suggest you read the Wikipedia article about this.

Begin by selecting a target image color to match and adjust, using shift + left-click on the image. This color will be the center of a range of colors that will be selected for adjustment. This range can be very narrow or wide, depending on other dialog settings. Select what color attributes will be matched using the checkboxes for hue, saturation, and lightness. Each of these will narrow the range of selected colors. If none are checked, all colors are selected. Match Level can be used to further widen the range of selected colors. 100% means only closely matching colors are changed.

The Output Color controls (hue, saturation, lightness) are used to set the new output color which will replace the selected input colors. You can also set this color from the image, using shift + right-click. The resulting color will be a mix of the original color and the new color. The new color part is determined by the Adjustment slider which can be set from 0 to 100%. Use the HSL checkboxes to determing which HSL components of input color are replaced with the corresponding HSL components of the output color. Use the sliders for output color HSL to adjust the new color. The output color is shown in the smaller box on the left, which is updated as you move the sliders.

Move the sliders and watch the live image updates to optimize the result.
This is not very intuitive, and practice will help.

begin by matching on hue and saturation, and replacing only hue - this means that the output color saturation and lightness will be copied from the original image colors, and only the hue will be replaced.

This function (like most others) can be used with Select Area to restrict the change to selected image areas.
Brightness Gradient (File View > Repair > Brightness Gradient)

This function varies brightness or color across the image. You can use this to compensate for uneven lighting or a color caste that varies across the image. The direction of change is determined by drawing a line on the image. Create the line by clicking on the image, then drag either end to set the direction wanted. In the example above, green is increased in the direction of the line. Edit the All curve first to adjust overall brightness (all colors), then adjust the individual RGB color curves if needed. The image reacts quickly to both line changes and curve edits.
Local Color (File View > Repair > Local Color)

This function can be used to make complex color corrections, whereby different parts of the image need different corrections. Select up to 9 control points on the image by clicking them with the mouse. The points are added to the list in the dialog window and to the image window, with labels A to I. The current RGB values are shown (or EV or OD units if selected). Change the RGB/EV/OD values in the dialog, and the image will be changed to match. Each pixel in the image is influenced by all the control points in the dialog, with the closer control points having more influence than those farther away. The slider Blend determines how widely the control points spread their influence. If delta is checked, the values shown are the deltas (differences) from the original image.

Match Colors (File View > Repair > Match Colors)

This function matches the colors in one image to those in another. A small spot, determined from a mouse click, is sampled from each image. The spot on the 2nd image will be made to have the same average color (RGB values) as the spot from the 1st image. The factors used to make the RGB values the same are then applied to all the pixels in the 2nd image. The most common use is to remove a color-cast from an image by marking a spot on the image that should have a given color which was taken from another image. 

Procedure: The dialog lists 5 steps to take in sequence. (1) Set a radius for the spot sample. The mouse cursor will have a circle of this radius which is the spot area that will be sampled. (2) Open the 1st image (press the [open] button for a file open dialog). If the current image is already the one you want, this step can be skipped. (3) Click on the image to take a color sample from the spot area enclosed by the mouse circle. You can change the radius and click again if wanted. (4) Open the 2nd image by pressing the [open] button. (5) Click on the image at the spot you want to match the spot color from the 1st image. The image colors will change within a second or two. You can change the radius and click on another spot if wanted, and the colors will change accordingly. Click the dialog [done] or [cancel] button to finish.
Color Profile (File View > Repair > Color Profile)
Use this function to change the ICC color profile. If you have images with Adobe RGB color, you can change to sRGB for better colors on a monitor, or for uploading to a web site. Any EXIF embedded color profile is removed, and the EXIF key "ICCProfileName" is set to the new profile. Because the relevant metadata is changed, a new file version is created automatically, and the input file is left unchanged with the old color profile. To view the color changes, use the KB arrow keys to switch back and forth between the old and new images.
You may need to install ICC color profiles. In Ubuntu, the package names are icc-profiles and icc-profiles-free.
Remove Dust (File View > Repair > Remove Dust)

Images made from dusty scanned slides can have many small dark spots - shadows of the dust on the slides. Historical photos from the internet often have a similar problem. This function can be used to remove the majority of such spots. Move the three sliders until the maximum number of dust spots are painted red, then press the [erase] button to erase them. Press [red] to bring back the red view, then you can adjust the sliders again and press [erase]. The "spot size limit" slider limits the size of the spots that will be erased. The "max. brightness" slider sets a threshold for ignoring spots that are not dark enough. The "min. contrast" slider screens out spots having low contrast with their surroundings. This process is usually a compromise. If the settings are not optimal, small features like tree leaves can be erased, or large spots may be left in place. Different parts of the image may need different settings, e.g. sky can be treated more aggressively than a building wall. You can simply use Erase Dust multiple times with different settings as needed to get all the dust spots. Or you can use select area to process the image in sections. If some spots are persistent, you can treat them manually with Smart Erase: set a small mouse radius and click on each spot to remove it. Spots from fibers (long and thin) are usually not removed automatically, but Smart Erase can be effective here.

Anti-Alias (File View > Repair > Anti-Alias)

This function can reduce pixelation (aka "jaggies" or "stair steps") in a low-resolution image. Press the [apply] button to make the change, then [done]. The result is sharper than using the Blur function. It may be useful to apply sharpening afterwards.

Note: this tool is only effective for pixelation with single-pixel "steps". If the image has been resized larger (steps are larger than 1 pixel) the algorithm does not work. It thinks the steps are legitimate because they are big. Pixelation in photos normally occurs only when a photo has been reduced and then enlarged. Pixelation is not a problem with normal photography - lens blur is usually larger than the pixel size.
Color Fringes (File View > Repair > Color Fringes)

This function is used to reduce chromatic abberation. Look carefully at the left photo, taken from inside a church. It has color fringes that were mostly eliminated in the processed image to the right (these images are 400% size and not very sharp). Color fringes can appear along high-contrast edges, especially in the outer image areas where lens distortions are usually greatest. To get rid of them, zoom the image to a maximum size and center on an area with color fringes. Move the slider controls slowly while watching the image, and leave them where the color fringes are minimized. To speed up the response time, select a small area first, optimize the color fringes in this area, then remove the area before pressing [done] so that the entire image will get the final corrections. The corrections are scaled so that the maximum correction is at the image edges and the correction at the center is zero.
Stuck Pixels (File View > Repair > Stuck Pixels)

Camera sensors may have defects causing isolated pixels to be always bright or always dark. This may be one RGB color or all of them. I have seen a case where a group of 3x3 pixels was always too red. This function can find such pixels in an image and repair them by substituting neighboring pixels.

Select the defect sizes to search for: 1 pixel, 4 pixels in a 2x2 block, or 9 pixels in a 3x3 block. The defects found are surrounded by small circles which you can toggle between write, black and red. Zoom-in to inspect these and determine if they are real defects. Use the contrast control to precisely select the defects. If set too low, small high-contrast spots in the image may be erroneously selected. If set too high, real defects may be missed. Use the [apply] button to erase the defects in the current image. You can apply the function many times using different settings if needed.

The currently shown (encircled) defective pixels can be saved to a file by using the [save] button. This file can be used later to fix the defects in any image made by the same camera: use the [open] button, select the saved defects file, then use the [apply] button to fix the current image. Using a saved defects file from one image to fix the defects in another image will only work if the two images have never been trimmed, or if exactly the same trim was applied to both images. This is necessary because the defective pixels in the two images must have the same locations. If more than one contrast setting or pixel group selection is needed to accurately find all the defects in one image, you can save the respective defect files and combine them manually into one file. Use any text editor for this.

I suggest you make a test images to find defects: Make a photo of a paper sheet or blank wall that is underexposed to come out gray. This image can be used to find both bright and dark stuck pixels.

Warp Menu (File View > Warp)
Unbend Image (File View > Warp > Unbend)

Panoramas of nearby subjects (typically buildings or interior rooms) may show straight lines that are curved, or buildings that are slanted. Warping of the images was necessary in the panorama process in order for the images to fit together. The Unbend function can be used afterwards to straighten the panorama image if needed. Vertical and horizontal dotted lines are drawn over the image, showing the unbend axes. Click or drag the mouse near the end of a line to move it. If values in the four input controls are changed, the image is warped in the manner indicated by the corresponding four icons. Increase or decrease the values and repeat until satisfied. Move the axes to change the centers of warping.

See also Warp Image for another method of correcting image curving and perspective.
Fix Perspective (File View > Warp > Fix Perspective)

This function can be used to straighten a photo made from an offset angle. The image on the left is the original photo, taken from right of center to aviud reflections. The image on the right is the straightened version. This function can also be used to straighten a building photographed from below or from the side.

Click on the four corners of the tetragon shape that you want to make into a rectangle (in the above case, the four corners of the painting or frame), then select [Apply]. Use [Reset] to go back and try again if needed. The clicked corners are marked with tiny squares enclosing small letters A, B, C, D. The upper left corner of the tiny square precisely marks the image position. Clicking near a marked corner will move it to the new position. After the 4th corner is marked, a new click replaces the closest mark. The [Trim] button will automatically trim the image at the selected corners. The trim and straighten can be undone in sequence. You can use the keyboard arrow keys to move the corner markers in 1-pixel steps. The arrow keys work on the last corner clicked or moved.
Warp Image (distort)

Warp area (File View > Warp > Warp area)
This function can be used to make distortions within an image. You can select an image area and drag the mouse to stretch this area with respect to the rest of the image. The image is like rubber. If the mouse drag begins within the selected area, then the area is warped within its current boundaries - the movement is maximum at the mouse pointer and declines to zero at the edges of the selected area. If the mouse drag begins outside the selected area, the area edges near the mouse can be pulled out beyond the original area boundary. Many mouse drags of different lengths and directions can be combined to achieve the desired results. When finished, you can select another area and do some more warping, or select [done] to exit the function. The method used limits loss of resolution from repeated warps: for each warp step, the total movement of each pixel is accumulated and the original image is warped to the latest pixel positions. The pixels are interpolated to reduce jaggies and improve sharpness.

Unwarp Closeup (File View > Warp > Unwarp Closeup)

Closeup face photos are often distorted, because areas closer to the camera are larger in the photo than areas farther away. This function can be used to reverse the distortion. Use Select Area to select the face first (does not need to be accurate). Click the image near the center of distortion (above example: between the eyes). Move the slider to optimize. If the face is turned away from the camera, experiment to find the best center.
Warp curved (File View > Warp > Warp curved)
This function is useful to correct perspective problems (see also Unbend). Drag the image from any position, using the mouse. The entire image will be pulled or pushed in the direction of the mouse, but areas near the mouse are moved more than more distant areas. You can straighten curved lines or deliberately curve the image. The control warp span determines the radius of warping around the mouse. 1.0 means the full image is warped, and smaller values confine the warp to smaller areas around the mouse.
Warp linear (File View > Warp > Warp linear)
This function is useful to correct perspective problems (see also Unbend). Drag the image from any position, using the mouse. This function works over a broader area than the curved warp and causes less image curvature. To minimize the addition of curvature, pull only on the image corners.
Warp affine (File View > Warp > Warp affine)
This function can be used to warp an image in interesting ways. Drag the image from a corner or edge using the mouse. The changes are purely linear so straight lines remain straight. This transform is called "affine". Technical details can be found with Google.
Flatten Book Page (File View > Warp > Flatten Book Page)

This function can flatten a photographed page from a book. If the book is thick, the pages bend downward at the binding, and the photographed text is squeezed together. This function straightens the the page and unsqueezes the text.
Photo Procedure
First, make the photo as good as possible to minimize the needed corrections. The page curvature can be reduced by holding the book half-opened. Place the camera over the center of the page, so that the top and bottom edge curves look roughly equal. Use lots of illumination to increase the depth of field, to insure the curved-down part of the page remains in sharp focus. Two persons working together can photograph 1-2 pages per minute.
Fotoxx Procedure
First, trim the image, keeping all of the page but little more. Rotate the page if needed. Use Fix Perspective to make the page more rectangular if needed. Start the Flatten function. Click the mouse along the top edge, creating visible marker dots at the clicked points. After 4+ points are available, a curved line is drawn through the points. Add more points and drag the points as needed to make the line conform closely to the page edge. Repeat for the bottom edge. Press [flatten] to flatten the page. The edges should now be straight (or straight enough). The text near the binding is still squeezed together. Unsqueeze the text by pulling the top and bottom sliders. The text is spread out in a way that is proportional the the slope of the top and bottom page edges, so the area near the binding is stretched the most. The [undo] button restores the unmodified image and the marker dots, which can now be adjusted.

Spherical Projection (File View > Warp > Spherical Projection)
Make a spherical projection of an image. Drag the mouse on the image to change the center of the projection (defaults to midpoint). The flatten control modifies the projection gradually from a sphere (left) to a flat image (right). The magnify control magnifies the resulting image up to 2x. If you want the margins to be transparent, be sure to save the file as .png instead of .jpg (JPEG files do not support transparency).

Selective Rescale (File View > Warp > Selective Rescale)

This function rescales an image to a smaller size, leaving selected areas unchanged. The goal is to increase the relative size of the area of interest. The image above was reduced, but the boat in the foreground was left unchanged. Image reduction may be in width or height or both. First, select the areas that are to be preserved using Select Area. Press the [proceed] button. The selected area is erased and the mouse cursor changes into a drag cursor. Pull the image inward from the upper left corner. This operation may be repeated as needed until you are satisfied. Press the [done] button. This function works best when the selected area(s) are small in comparison to the entire image. The pixel rows and columns that intersect the selected areas are not changed. Other areas are compressed as the image is pulled inward.

Make Waves (File View > Effects > Make Waves)

This function distorts an image into a wave pattern, as if it were being viewed through turbulent water. The dialog allows you to change the mean horizontal and vertical wavelengh, amplitude and variance. The "perspective" input allows the wavelengths to gradually lengthen from top to bottom. Like most effects, this function also works within a seleced area.

Twist Image (File View > Effects > Twist Image)

This function twists the image around a point chosen with a mouse click or drag. Click the desired position and move the Twist slider the amount wanted. You can also drag the mouse around the image to change the center of twisting. The Center slider untwists the central area relative to the rest. The Angle slider rotates the entire image.

Effects Menu (File View > Effects)
Pencil Sketch (File View > Effects > Sketch)

This function transforms a photo into something like a pencil sketch. Dark pixels are aggregated into fewer pixels, leaving vacated areas brighter. Contrast can also be used as a proxy for dark pixels. Threshold can be used to filter the input image by brightness. Clip Level is used to filter the output to further reduce isolated or marginally dark pixels. Choose colors for foreground and background. Two algorithms are provided. Results may look more interesting with one or the other. Reducing the size of the input image may also give more interesting results.

Cartoon (File View > Effects > Cartoon)

Transform a photo into a cartoon-like drawing. Black lines are drawn over the "edges" of objects in the image, wherever the brightness or color changes abruptly. Line Threshold sets the sensitivity for edge detection and line drawing, causing more lines (lower threshold) or fewer lines to be drawn. Line Width makes the lines thicker or thinner. Blur Radius controls a blur function which can make the lines look more curvy or less jagged. Kuwahara Depth controls a sharpen function which can strengthen the image edges.

This function can be quite slow to react if the image is large and if the blur and kuwahara controls are set to high values (10+ seconds to respond). It works faster and better on smaller images, around 2 megapixels or less. I suggest you start with small values (2-3) for kuwahara and blur, then adjust line threshold to optimize the density of the drawn lines. Now change kuwahara and blur in small steps and re-adjust line threshold. If you are working with a large image, I suggest you select a small but important area within the image so that optimization can proceed faster. Then delete the area and do the entire image. You may be close to optimum already.

Other edit functions, applied before or after Cartoon, may enhance the effect. These include color saturation, tone mapping, color depth, texture, and warp curved. Paint and Clone are useful to remove minor flaws manually. Shadows in the image are a particular problem, since they cause lines to be drawn where normally not wanted.
Line Drawing (File View > Effects > Line Drawing)

This function transforms a photo into a line drawing showing outlines of objects within the image. Edges (sharp transitions in brightness or color) in the image are brightened, and the rest of the image is darkened.

There are three sliding controls. Threshold: how bright an edge must be in order to get enhanced, from "show no edges" at the low end to "show all edges" (even faint ones) at the high end. Width: width of the enhanced edges, from 1-pixel to about 5 pixels. Brightness: brightness of the image itself, from dark (show only the outlines) to full brightness. The black/white checkbox converts the image from color to black and white, and the negative checkbox makes a negative image (colors are replaced with their compliments).
Color Drawing (File View > Effects > Color Drawing)

This function transforms a photo into a solid color image that looks like an illustration. The Threshold slider separates the image into brighter and darker areas, with the boundary set at a brightness level determined by the slider. The other two sliders regulate the brightness of these two areas. At the settings shown here (Dark Areas pushed left, Bright Areas pushed right), the darker areas are black and the brighter areas as as bright as possible with intense coloration. If the sliders are moved to the opposite sides, the original image is restored. Move the sliders until the image is optimized.

This function can be used to clean up a smudgy blackboard or whiteboard image by separating the writing cleanly from the background (if the background smudges are weaker than the writing). It may help to apply Sharpen to the image beforehand, to increase the contrast of the writing. Use the unsharp mask method with a large radius.
Graduated Blur (File View > Effects > Graduated Blur)

This is another function to blur an image, but it works differently. In the dialog, you specify a contrast limit and a blur radius. Only pixels with less contrast than the given limit are blurred, and the blur radius ranges from 1 to the given value for pixels with a corresponding contrast ranging from the given limit to zero. In short: low contrast pixels are blurred more than high contrast pixels. This can be used, for example, to smooth skin tones without blurring hair or reducing the sparkel in the eyes. Taken to extremes, it produces a "cartoon" effect, especially when used in combination with other retouch and effects functions.
Embossing (File View > Effects > Embossing)

This function transforms a photo into a simulated relief or embossed image. The radius setting determines the feature size or level of detail. The depth setting determines how deep the features go into the surface. The upper 60% of this image was embossed.
Tiles (File View > Effects > Tiles)
This function transforms a photo into an array of large monocolor tiles. You can control the tile size and the thickness of the gap between tiles. This is also called "pixelate" or "pixelize". Use Select Area to confine the transform to a limited area, such as a face.
Dots (File View > Effects > Dots)

This function transforms a photo into a array of dots, like a comic book picture or Roy Lichtenstein painting. The only control is dot size. Also experiment with using color saturation, color depth, or other functions before and after using Dots.
Painting (File View > Effects > Painting)
This function transform a photo into something looking more like a painting. It reduces the number of colors, maps each contiguous pixel area having the same color, and then consolidates smaller areas into adjacent larger areas having the best color match.

color depth sets the number of colors to use: 1 = 8 colors, 2 = 64 colors ... 5 = 32768 colors.
patch area goal sets a lower limit for areas that will have their own color: areas smaller than this number of pixels will be absorbed into an adjacent area with the nearest color match.
req. color match sets the minimum color match required for a smaller area to be consolidated into an adjacent larger area: 0 = don't care (maximum consolidation), 100 = perfect match required (no consolidation).
borders determines whether the colored areas will be delineated with a thin black border, like irregular tiles in a mosaic. After using this function, using the Embossing function can add interesting texture to the image.
Vignette (File View > Effects > Vignette)
This function is used to correct the darkening sometimes seen around a photo's periphery, because less light reaches the edges compared to the center.It can also be used to highlight or colorize an object or area within an image.

Click or drag the mouse on the image to change the vignette center, which is initially at the center of the image.

Select Brightness to change the brightness of the image in a radial pattern: Adjust the left or right end of the curve to change the brightness of the center and edges of the image respectively. You can give a dark surround to a portrait face, or you can fix an image with darkened corners. The curve middle level corresponds to no change. Use lower values to darken and higher values to brighten. The example above gradually darkens the periphery of the image while leaving a broad central area unchanged.

Select Color to add a chosen color to the image in a radial pattern. Curve values of zero represent no change, and higher values add the chosen color to the image. The highest value corresponds to 100% color. Use this function to add a color surround to an image, e.g. surround a face with a gradually increasing color.

Irregular Vignette
You can make a vignette with arbitrary shape as follows:
 + Select Area - select the image area to remain visible
 + Invert the area to select the areas outside the image
 + Set a blend width value for the edge fade-out width
 + Keep the Select Area dialog active
 + Paint Image - paint the outside areas with the desired color
     (the image edges will fade-out over blend width pixels)
 + Adjust the blend width value and paint again until satisfied
Texture (File View > Effects > Texture)

This function adds a textured surface to an image or selected areas within an image. Radius determines the texture pattern size. Strength determines the intensity of the pattern, from almost invisible to dominant.
Pattern (File View > Effects > Pattern)

Add a background pattern to an image. A small image file (pattern file) is used to cover the current image by duplicating the file, like a tiled wall. This file can be a real pattern (e.g. an image of canvas cloth, a brick wall, a repeating geometry ...), or any other kind of image. The pattern is made semi-transparent, so that the base image appears to be printed over the pattern, or the pattern over the image. Many pattern files can be found using a Google search for "pattern image". Download some of these and trim them if needed to a size around 200-500 pixels. For convenience, add these to the supplied pattern files in /home/<user>/.fotoxx/patterns.

Use the [Browse] button to select a pattern file. The selected pattern will be tiled to cover the base image. The pattern is partly transparent so that the base image shows through. Use Zoom to grow or shrink the pattern size. There are two methods to mix the pattern with the base image. The pattern opacity can be set 0-100%. The base image is used to fill the unused opacity - e.g. if the opacity is set to 30%, then the final image will be 30% pattern and 70% base image. Contrast is used to modify the base image brightness using the pattern brightness as a template. The two parameters can both be used and mixed in any ratio.

Width and Height are initially set to the size of the pattern file. You can adjust these smaller, which will cause less of the pattern to be used for duplication. If the pattern file contains an image that repeats at fixed intervals both horizontally and vertically, the [Calculate] button can be used to set width and height to match. The result will be a continuous pattern without any edge effects.

If the pattern is irregular and edge effects appear where the duplicated patterns are joined, you may be able to improve this. Use Width and Height to revise which part of the pattern image is used. The two Overlap values determine how much the duplicated patterns overlap at the edges, horizontally and vertically. Add some overlap to mask edge effects.

Select Area can be used to apply a pattern to part of an image, or different patterns to different parts. After applying a pattern to an image, it might be interesting to use Embossing or Tone Mapping to add a 3-D effect to the pattern.

Useful pattern files in LibreOffice: /usr/lib/libreoffice/share/gallery/www-back
Mosaic (File View > Effects > Mosaic)
Create a mosaic image using tiles made from all your images.

Specify the tile size in pixels (e.g. 36 x 24) and press [Tiles]. Tiles will be created from all of your images (actually the thumbnail images are used since their small size makes the process run much faster). This may take some time (speed is over 10K images/min. on a strong PC). If you change the tile dimensions, press [Tiles] again to regenerate the tiles. This may work much faster since the images have been cached in memory by the OS. The generated tiles are saved to a file and loaded again the next time the Mosaic function is used. Regenerate the tiles only when new images have been added to your collection or if you change the tile size.

After the tiles are created, press [Image] to convert the current image into a mosaic using these tiles. This takes only a few seconds. You can process additional images without regenerating the tiles. Tiles are chosen by matching the average tile color to the average image color at the tile position. If thousands of images are available and if the range of colors is good enough, the mosaic will turn out quite good. Use the mouse wheel (or CTRL+left click) to zoom-in on any part of the image to see the tile images.

The Tile blending slider will cause the image to be blended with the tiles, making it look better if the tiles are a bad color match. If the blending is less than about 50%, the tiles remain almost as clear as before (the eye compensates the false tint).

After a mosaic is created, you can click on any tile to get a larger popup image. This is the full image for the tile, so you can drag the window as large as you like and it will remain sharp. A mosaic image can be saved like any other edited image, but if a saved mosaic is opened, clicking the tiles for a bigger image will not work. Regenerating the mosaic is quite fast, so do this if you want the popups to work.
Custom Kernel (File View > Effects > Custom Kernel)

Apply a custom convolution kernel to an image. The underlying technology is explained in Wikipedia. Input a kernel size, a multiply factor, an add factor, and fill-in the table values. The values can be saved into a file and retrieved later by using the [Save] and [Load] buttons. [Apply] applies the kernel to the image, and can be repeated for multiple applications.
[Reset] restores the original image status.

Several kernel example files are available initially. You can modify these and save with a custom name. 

Math: the brightness values for each N-by-N block of pixels in the image are multiplied by the corresponding values in the kernel matrix and added together. This number is multiplied by the multiply factor, and the add factor is added to it. This final value becomes the new brightness level for the image pixel at the center of the N x N block.


Directed Blur (File View > Effects > Directed Blur)

Pull a location on the image using the mouse. The area around the mouse will move with the mouse and become blurred in this direction, a "1-dimensional" blur. Blur span can be used to broaden or narrow the size of the area being blurred. Intensity determines the strength of the blur, from barely visible to completely blurred.

Blur Background (Bokeh) (File View > Effects > Tilt-Shift)

Blur the background image while leaving the foreground sharp. The foreground is defined by using Select Area to select one or more areas that are to remain sharp. If there is no selected area to begin with, the select area dialog is started automatically. After selecting the foreground areas, invert the selection so that the background is now selected (use the [invert] button in the Select Area dialog). This area is the one that will be blurred. There are two blur methods available: Constant blur uses a constant blur radius for all areas blurred. Increase blur with distance uses the minimum blur radius for pixels adjacent to the foreground (i.e. on the edge of the background area), and the maximum blur radius for pixels at the maximum distance away from the foreground. This requires that the edge-distance for all background pixels be calculated, which can take considerable time for a large image. This is done automatically if required. Various settings for blur radius can then be tried without recalculating the edge distances.

Tilt-Shift Effect: You can do this by selecting a horizontal rectangular area to remain sharp.

Alien Colors

Repaint an image or selected area with random alien colors. You can control the rough pattern size and the intensity (from barely visible to dominant).

Undo/Redo Button (File View > Undo/Redo)
If an edit function is active and the image has been changed:
  + left mouse click will undo the current edit
  + right mouse click will redo the edit
This allows you to rapidly compare the "before" and "after" images for the current edit function.
If no edit function is active, but one or more edit functions were done to the current image:
  + left mouse click will undo one edit step per click
  + right mouse click will redo one edit step per click
  + if combined with the A-key, undo/redo ALL edits (compare original and final images)
  + middle mouse click pops-up a list of all edit steps - select any step to go back to
  + use the escape key to abandon the list without making any selection


Tools Menu (File View > Tools)
Index Image Files (File View > Tools > Index Image Files)

top image directories, one or more

thumbnail directory
The Index Image Files function runs whenever Fotoxx is started. This function will create missing thumbnails, replace outdated ones, and refresh the metadata index using current data from your image files. This may need significant time if you have many thousands of new images. The speed can range from 1000 to 3000 images per minute, depending on computer speed and average image file size. If there are no new image files, indexing completes quickly. Indexing can also be started manually from the Tools menu.

Image files modified or moved within Fotoxx are taken care of automatically. The Index function is used only for new image files created from outside Fotoxx (e.g. a new batch of photos was added), or for files moved or renamed from outside Fotoxx.

Enter your top image directories (e.g. /home/<user>/Pictures). Use the [browse] button to locate and add directories. These directories and any subdirectories containing images will be processed. It does not matter if other files are mixed with the images. The simplest way is to use /home/<user> as the only top directory, but it is better to separate the image files from the hundreds of thousands of other files that may be under /home/<user>. Delete an entry by clicking the corresponding X.

Enter the thumbnails directory where thumbnail files will be stored. Use the supplied default or set your own location. The directory name must end with .../thumbnails, and this will be added to your selection if needed. The directory is created if not already present. Indexing will run faster if this is on a separate physical disk from the image files. Thumbnail files need typically 1-2% as much space as your image files (20-40 KB instead of 2-5 MB for typical JPEG files from a modern camera).

If you have used directory or file names to classify your images, you can make immediate use of these in the Search Images function. If you have saved dates, captions, tags, geotags, titles, or ratings in your image metadata (using other image edit apps), these will also be searchable. After the images have been indexed, searching them by any of these criteria is almost instantaneous. Other items in the image metadata can also be searched, but at a slower speed. See Search Images for details.

Fotoxx Startup Time
If you have a huge image collection, the first startup after a reboot may need significant time, even if there are no new image files. Subsequent startups are faster because the image index file and the image directories are now cached in memory. If startup time is still a problem, you can bypass the indexing. This may be especially useful if you use a file manager (e.g. Nautilus) to start Fotoxx with a selected image file, and you want the image to display instantly. See the User Settings topic immediately below for more information.
User Settings (File View > Tools > User Settings)
Various user preferences and settings are collected in this dialog.
They are also saved in the file  /home/<user>/.fotoxx/parameters.

Startup Display  Determines the initial display when Fotoxx is started:
Recent Files Gallery: the most recently seen image files (gallery display)
Newest Files Gallery: image files most recently added to the image database (gallery)
Specific Gallery: the specified directory gallery
Album Gallery: the specified album gallery
Previous Gallery: the gallery last used in the prior Fotoxx session
Previous Image File: the file last viewed in the prior Fotoxx session
Specific Image File: the specified image file
Blank Window: start with no current image and the first top image directory gallery
Opens a dialog to browse for the starting directory, album, or image file
Menu Style The menu style: icons only or both text and icons.
The background color for the main window containing the current image.
This is the color outside image margins when image width and height do not fit the window.
Dialog font
The font name and size to use in all menus and dialogs (Bold, Italic, etc. are ignored).
Zoomed Image
Drag: image moves with the dragged mouse.
Scroll: image moves against the dragged mouse (like invisible scroll bars).
Fast: movement is magnified so that the entire image can be scrolled with one sweep of the mouse.
Choose 1-8 zooms (mouse click or + key) for each 2x increase in image size.
JPEG quality The default quality value when saving an image as a jpeg file type.
Curve node
 capture distance
The minimum node separation for edit curves. Also the mouse capture threshold when a node is clicked or dragged. The default is 5% of scale, allowing up to 20 nodes in a curve. If you use a touchpad instead of a mouse, set this value higher to compensate for lower positioning accuracy.
Map marker size
The size of the markers (red dots) marking image locations on maps.
last file version
Show only the last version of image files, for both file view and gallery view (if a directory).
shift image right
If the window is wider than the image, shift the image right to maximize left margin for dialogs.
image index level  
(2 parameters)
0/1/2 = no image index / old index only / old + search for new image files
This affects startup speed. See below for a complete explanation.
RAW file types The RAW file types recognized. If your camera uses something else, add it to the list and this may work.
You can also shorten the list to those file types you actually use.
video file types
The video file types recognized (e.g. .mpeg .mp4 .h264  etc.)

Image index level
These two parameters govern a tradeoff between fast Fotoxx startup time and the completeness of the image index. A complete image index is required for accurate results from image search and map functions. Building a complete image index when Fotoxx starts can take from 0.1 seconds to many hours (indexing never done and you have a million image files). The time to start Fotoxx depends on the following factors:
If you start Fotoxx by selecting a file from your file manager (e.g. click on the file name in Nautilus), you may want to see the image immediately and not wait for indexing. You can control this with the two parameters image index level.
You can also start the index process manually (Tools > Index Image Files) if you want to use search and map functions with complete results. You do not have to go back to User Settings and change the parameters.

Keyboard Shortcuts (File View > Tools > Keyboard Shortcuts) (key K) 

This function is used to view or change custom keyboard shortcuts. The currently assigned shortcuts are shown in the first window. If you press the [Edit] button, the second dialog is shown, where you can add and change keyboard shortcuts. Enter a new shortcut using the keyboard. You can use the keys A-Z, 0-9, F2-F9, and most of the symbols (# $ & ^ < etc.). You can combine a key with Ctrl, Alt or Shift: Press and hold Ctrl, Alt or Shift, then press the key, then release both. Select one of the available menu assignments from the drop-down list. To remove a shortcut, select it and press [Delete]. Press [Done] when you are finished. If you press [Cancel] or [x] all changes will be discarded.
Brightness Distribution Graph (File View > Tools > Brightness Graph)

This function opens a small window that shows a brightness distribution graph of the current image in the main window, or the currently selected area of the image. This graph updates immediately for new images or as edit functions change the image. There are four graphs in four colors: red, green, blue graphs are for the respective colors. The black graph is for overall brightness. Use the buttons [Red] [Green] [Blue] and [White] to select the colors to show. White means all colors added together.
Grid Lines (File View > Tools > Grid Lines) (key Alt+G) 

This function adds or removes horizontal and vertical lines across the image. The lines are useful when an image must be rotated for horizon alignment, or when an image is unbent or warped to straighten walls or other objects in the image. The settings for x- and y-spacing control the spacing (pixels) between the lines. If the controls for x- and y-count are NOT zero, then the x- and y-spacing values are ignored and the number of lines will be set to these counts. Example: set x- and y-count to 2 lines each in order to divide the image into thirds horizontally and vertically. The x- and y-enable checkboxes can be used to enable and disable the vertical and horizontal lines separately. The keyboard shortcut Alt+G can be used to toggle the grid lines on and off (this shortcut can be changed). If an image is printed with grid lines enabled, the grid lines are also printed. The x- and y-offset controls can be used to shift the grid lines to intersect a desired point in the image.

Several edit functions have a button [grid] which starts this same dialog. The resulting grid line settings are specific to that function only, and will be restored whenever that function is in use.
Line Color (File View > Tools > Line Color) Change Color of Foreground Lines
Some functions draw lines over the image (Trim/Rotate, Area Outlines, others). You can change the color of these lines to maximize contrast against the background image. The small dialog can be left open while editing, to conviently switch among the available colors (black, white, red, green).
Show RGB (File View > Tools > Show RGB)

When a point on the image is clicked, the RGB values are shown in a dialog window. The last 9 clicked points are displayed. The values have the format xxx.dd, where xxx is the upper 8 bits of the color value and .dd is the lower 8 bits. The range is 0.00 to 255.99. The lower 8 bits are zero unless the image is being edited or the image is a 16-bit TIFF or PNG file. EV (exposure value) is an alternative unit, useful for precise color adjustment. EV is zero for mid-brightness (128). The outputs are updated immediately if the image is being edited. The last nine points clicked are shown. The points are labeled on the image corresponding to the letters A-I in the dialog window. If "delta" is checked and the image is being edited, then the changes are shown instead of the absolute values. If no edit is active, "delta" does nothing.
  RGB 0 1 2 4 8 16 32 64 128 256
  EV nan -7 -6 -5 -4 -3 -2 -1 0 1

Magnify Image (File View > Tools > Magnify Image) (key X)

This function magnifies the image in an area around the mouse pointer. Left-drag the mouse around the image to magnify different areas, analogous to viewing a printed image through a magnifying glass. Use the dialog to adjust the radius of the area and the amount of magnification. A mouse click will end the magnify, and a new mouse drag will start it again. Use the X-key shortcut to start or end the Magnify function.
Dark/Bright Pixels (File View > Tools > Dark/Bright Pixels)
This function is used to highlight the darkest and brightest pixels in an image. Adjust the two sliders to set the brightness thresholds, which are initially 0 for dark pixels and 255 for bright pixels. Pixels with a brightness less than the dark threshold or greater than the bright threshold are highlighted on the image. The image responds quickly to changes in the sliders. You can use this function in parallel with edit functions to control edit results.

Monitor Color (File View > Tools > Monitor Color)

Eight color bands are written across the screen with brightness from zero (black) to 100%. You can use this to adjust the brightness of your monitor. The left end of each stripe should be as black as possible, but you should start to see some color within a few mm from the left edge. If the completely black portion is wider than this, adjust the monitor. There are 255 brightness steps from black to 100% (8 bits per color). The steps are too small to distinguish with the eye. This evaluation should be done in a darkened room (with little external light falling on the monitor).

Monitor Gamma (File View > Tools > Monitor Gamma)

Gamma determines how RGB brightness values (0-255) are converted into brightness on the monitor. The standard value is 2.2 and this should normally be used for image editing. Adjust the dialog slider until the middle band has the same brightness as the upper and lower bands at scale location 2.2. Be far enough from the monitor that you cannot see the fine lines in the chart. The chart only works at 100% size, so do not zoom the chart. The command line utility "xgamma" is required (normally present).

The chart image originates from Norman Koren. The linked web site has more information about this chart.
The chart here in the User Guide has been reduced
Change Language
(File View > Tools > Change Lanuguage)
This function allows you to change the GUI to one of the available languages. If your language is not available or has missing translations, consider making a translation. See menu Help > Translations.
Missing Translations (File View > Tools > Missing Translations)
This function lists all missing translations to a popup window. Translations left as English are not reported, since this is often deliberate, e.g. words like "font" or "icon".
Printer Color Calibration (File View > Tools > Calibrate Printer)
This utility may be able to improve the color accuracy of printed images.

How It Works
A chart of known colors is printed on the target printer. Some of the printed colors will be slightly wrong due to printer imperfections. This printed page is scanned into a file, and the colors in this file are compared to the original colors that were sent to the printer. Any differences are errors that are now known. When an image file is printed, these errors are subtracted from the image colors before printing. The printer adds the errors back, leaving a result that is theoretically correct. Practice may be otherwise. My own result was a modest improvement, detailed below.
Hopeful Assumptions
Perform the following steps in sequence, as listed by the dialog window. Each step has instructions to perform the step. All files normally reside in the directory /home/<user>/.fotoxx/printer_color/.
  1. Generate and print the color chart file (printchart.png) on the printer to be calibrated.
    Use a large paper size (A4 or US Letter), vertical paper orientation, no margins.
  2. Scan the printed chart into a PNG file. Use 300 dpi or more to make a large file.
  3. Edit the PNG image to trim off margins left by the scanner. Save the edited image
    as <chosen-name>.png. Use a name indicating the printer settings and type of paper.
  4. Process the edited chart file to create a color map file <chosen-name>.dat.
    Use a name indicating the printer settings and type of paper used.
  5. Print a color-adjusted image. You are asked for the color map file created in step 4.
Once you have made the color map file, you can print any image using step 5 only.
There is also a File menu function to do step 5 only: Print Calibrated.

Precautions For Best Results
Results (my Canon printer)
A standard color chart was scanned and printed on photo paper. The left print had no adjustments. The right print was adjusted. This image has all three charts in one photo. The printer did a fairly good job by itself, but the adjusted print is slightly better. Some colors are more accurate. Others are little changed.

You may be able to find a real ICC color profile for your printer and its proprietary inks and photo paper. Using this would most likely produce better results. Check the installation CD supplied with your printer, and also the manufacturer's web site. There are also professional services to generate an ICC color profile. The procedure is similar to the one described above: you print a color chart supplied by the service, send the printed chart back to them (along with some money), and receive an ICC profile, a file which you can install. Try a web search for "icc profile service".

Uninstall AppImage
(File View > Tools > Uninstall AppImage)
This function will completely remove the AppImage package.
Desktop menu/launcher, icon, and executable file are all deleted.
Resources (File View > Tools > Resources)
This is a diagnostic tool to monitor resources, especially memory leaks.
The following data is output to the log file (or terminal window):
    process time: CPU time used, since the last time shown
    zdialog counts: total dialogs in memory and those still active (visible)
    zmalloc counts: memory allocations and releases since the last time shown here
    MB: total allocated memory at this time in megabytes

Help Menu (File View > Help  and  Gallery View > Help)
Quick Guide
This is a 1-page introductory document with Fotoxx essentials.

User Guide  (key F1)
The user guide (this document) is displayed (created using the WYSIWYG HTML editor Kompozer).

User Guide Changes
This is a summary of recent changes in the User Guide. The intent is to enable you to survey the changes without reading the whole document.

Edit Functions Summary
A one-page "quick reference" summary of the image edit functions is displayed.

Displays the README file distributed with Fotoxx, which may contain new information about installation or dependencies. When you install a new release of Fotoxx, you should look at README and the Change Log to check if there is anything special you need to be aware of.

Change Log
Displays the change log file distributed with Fotoxx, containing details about functional changes, additions, or bug fixes for the current and previous releases.

Displays a short text file which explains how to make a new translation or change an existing one.

Home Page
Shows the Fotoxx home page from the Internet. Look here for program updates (the page named "recent changes"). This page is published via RSS and you can subscribe to get timely notification of changes.

This displays a short message about the Fotoxx version number, license, credits, and contact address.

Gallery View

Image Management in Fotoxx
A gallery of thumbnails can represent a file directory, the output of an image search function, one of the built-in galleries (recent files, newest files), or an album (an ordered list of files with a user-given name). Batch Convert can accept files selected from any gallery and output converted files into a directory. The image cache is a holding area for user-selected files that can be later added to an album. Manage Albums (below) can create new albums from a gallery or the image cache, or select images from galleries and add them to the image cache.

Gallery Menu (Gallery View > Menu)
Sync Gallery (Gallery View > Menu > Sync Gallery)
This is a duplicate of the Sync Gallery function in File View.

All Directories (Gallery View > Menu > All Directories) (or [TOP] button > ALL)

All top image directories are shown initially.
Click on [+] to unroll subdirectories, or on [-] to roll them back in. You can click on any directory name to get a gallery list of all the images in that directory. Keep the window open for a convenient means to navigate anywhere in your image collection.

Manage Albums (Gallery View > Menu > Manage Albums)
An album is an arbitrary sequence of images that is manually assembled from existing images. This is one method to make groups of associated images. An album is simply a list of its member image files. The image files themselves are not copied or changed. A given image file can be a member of multiple albums, or may be present more than once within an album. Albums can be used to group images with some shared attributes, such as photos from a vacation trip, photos of a given person taken at different times or events, a "best photos" collection, etc. You can add and remove images in an album and rearrange the order of the images. Once an album is made, you can call it up by name and it becomes a gallery. This gallery works like any other: you can scroll through the gallery, step through the images with the [Prev/Next] button, or edit the images. Keep in mind that editing an image in an album will edit the underlying image file, so any other way to view this image will show the same changes.
Image Cache
This is an intermediate storage area used to hold selected images for later insertion into an album. In general, you select image files from gallery windows and add them to the cache, then you make a new album with images from the cache, or you add the cached images to an existing album at a chosen position within the album.
Manage Albums Dialog

: Start a new album or replace an existing one. The dialog shown immediately below is started.
Choose: Choose an album to view or edit. The gallery window will show the album current images. Use the thumbnail popup menu (below) to add or remove images.
Add: Add images to the image cache using the standard dialog for selecting images from gallery windows (link). Select image files in any order from any gallery. Selected images are added to the image cache. Add cached images to the album using the popup menu (below).
Remove: The standard dialog for selecting images is started. Choose images from the current album gallery to be removed. The images are left in the image cache in case you want to insert them into another gallery or a different place in the same gallery.
Clear: Discard all images in the image cache.
Delete: Select an album to delete. Image files are not deleted.
New Album dialog

Specify an album name, or use the [browse] button to select an existing album to be replaced. Select one of the three options. Option 1 creates the album with no images. Option 2 fills the album from cached images, if any. Option 3 creates the album from the current gallery. This may be a directory, the output of an image search, or an album.
Right-click Popup Menu

Copy to Image Cache
Add the clicked image to the image cache.
Cut to Image Cache
Remove the image from the album and add it to the image cache.
Copy to Clipboard
Copy the image to the clipboard (for other apps to paste).
Paste Image Cache Here (keep) 
Insert all cached images at the clicked position.
Click roughly between two thumbnails where the images will be inserted.
Paste Image Cache Here (clear) 
Same as above, but the cache is cleared.
Paste Current Image File Here
Inserts the current image file at the clicked position.
Remove from Album
Remove the clicked image from the album
Popup Image
Pop-up a large resizeable window for the image. Replace previous popup window.
View Metadata
Metadata short report for clicked image file.
Drag and Drop
You can rearrange images within an album by dragging thumbnails with the mouse. Drag the thumbnail until the mouse cursor changes to a small image of the thumbnail. Continue dragging this image to the position where it should be inserted, and release the mouse button. Position the mouse roughly between the images where the dragged image is to be inserted. If the drag approaches the top or bottom edge of the window, the gallery will scroll to bring more images into view. You can use two instances of Fotoxx to make the selection or movement of many images faster. Drag and drop images from any gallery on to an album gallery. The source gallery can also be an album or the results from an image search function. The image cache is also a gallery which can be used as a source, but not a destination.

Sorting Albums
Albums have an image sequence that is determined by the user. Like other galleries, they can also be sorted. If an album is sorted, it is out-of-order for editing purposes and cannot be edited. This is because the position for inserting or moving an image is now meaningless. Therefore, refresh the album view by using the top panel [Albums] button before editing.

TIP: If image files are renamed or moved using Batch Convert, and if deletion of the original image files was also specified, then all albums containing any of the input files are updated to reflect their new names and locations. Therefore, don't just rename directories if they contain images in albums, or manually move image files among directories. Instead, use Batch Convert to move the image files to the new directory, then delete the old directory if it is left empty.

Update Albums (Gallery View > Menu > Update Albums)

Update the image files in selected albums with the latest file versions. If image files are edited and new versions created, albums will still reference the prior versions. This function checks album files for later versions and replaces the album files (links) where needed. You can select any number of albums for processing.
No files are deleted or moved. The file names (or links) within albums are updated.

Replace Album File (Gallery View > Menu > Replace Album File)

Replace an old image file in all selected albums with a new image file, or add a new file to the albums following the designated old file. If an image file is edited and a new version or new file is created, albums referencing the old file may need updating. Choose any number of albums and specify the old file name and the new file name. No files are deleted or moved. The file names (or links) within albums are updated.
Slide Show (Gallery View > Menu > Slide Show)
With this function you can show a pre-selected sequence of images.
There are three dialogs used to define and customize a slide show.

Use the Manage Albums function to assemble the images for a slide show as an album with an assigned name. This allows you to collect images from anywhere in your image database and order them as desired. In the slide show dialog, press [Select] and choose an album from the list provided. You can use the current gallery for the slide show by pressing the button [use gallery]. Use the gallery [TOP] button to choose another gallery.

Press the Proceed button to start the slide show with the first image (or the current image, if a member of the slide show album). Use the escape key or F11 to exit the slide show and return to the dialog.

The spacebar can be used to pause and resume between slides. The B-key can be used to blank the screen and pause the show. Press again to restore the current image, or press the spacebar to resume with the next image. You can use the left and right arrow keys to go back and forth within the sequence of images. You can interrupt the slide show by pressing the ESC key for a gallery view. Click on a thumbnail image, and this will be the next image to show. This allows you to skip around more easily than stopping and starting the show each time. The M-key can be used (whenever the slide show is paused) to start the magnify function to view selected parts of the image at higher size. The N-key can be used to bypass the normal image display time and go immediately to the next image. The arrow keys bypass the animated transition to show the previous or next image immediately. The N-key keeps the normal transition and shows the next image. Press KB Functions for a popup list of all the keyboard functions (above image).

Dialog Controls:
Seconds: The standard time each image is shown.
This time can be extended for selected images in the Images Preferences dialog (below).
Clip Limit: Images are scaled to fit the window. If the image and window aspect ratios are different, this will create black margins above and below or left and right of the image. You can optionally make the images expand to fill these margins and cut off the opposite sides of the image (e.g. if the margins are on the left and right, the image is expanded to fill these margins and cut off the top and bottom equally). You control how much of this is allowed with the Clip Limit, which is the percent difference in aspect ratios above which expansion and clipping will not be done. Zero means no clipping is done, 10% means that images with 10% or less difference in aspect ratio will be expanded and clipped.
Music File: An optional music file or playlist that will start when the slide show is started.
Full Screen: If checked, images are shown full-screen without menu, title bar, etc.
Auto-replay: if checked, the slide show will start over after reaching the end.

Press [transitions] to start a dialog to select and customize the transitions between images. These include instant replacement, fade-out/fade-in, and many animated methods of image replacement (e.g. the new image expands from the center to replace the old image). Select the transitions to be used and whether they are used randomly or in sequence. The slowdown parameters can be used to slow transitions that may operate too fast on some PCs (some may be too slow on slow PCs, but this cannot be helped). The preference parameters specify a relative preference which will influence how frequently the transition type is used when a random sequence is selected.

The buttons [load] and [save] allow you to save transition settings in a file and load them later. These files are independent of the slide show files. A slide show will default to the transition settings last used for that slide show, but you can always override these by using the [load] button to load some other settings, or changing them in the dialog.

Press [image files] to start a dialog for image preferences. These are optional. An image is selected for customizing by clicking its thumbnail (press the [gallery] button or G-key to show thumbnails). The dialog is filled-in with default settings or the previous settings for this image. Enter revisions and press [done], or click on the next image to be customized. If Play Tone is selected, a tone is played when the image appears during the slide show. The Show Caption / Show Comments times determine how long the image caption and comments will be shown above the image. After this time they disappear. Captions and comments are edited with Edit Metadata. The Wait times determine how long the image will wait before and after the optional zoom, until moving on to the next image. These are always used, even if there is no zoom. Zoom type selects zoom-in (image approaches) or zoom-out (image recedes). Zoom size controls how much the image will be zoomed and Steps determines how many steps are made during the zoom. 1.0 means no zoom, and 3.0 is the maximum zoom (image is 3x larger). Use at least 300 steps for a smooth zoom, and more than this if you want it to zoom more slowly. To set the center of the zoom, press the [Zoom Center] button first, then click on the thumbnail image at the desired zoom center. Transition is used to select a transition type to be used from this image to the next image. If transition type "next" is selected, then the normal transition sequence is used, as specified in the Transitions dialog.
Sequence of slide show events for each image:
  +  play the tone if specified
  +  show the caption and comments for the specified times (may be zero)
  +  wait for the first interval (may be zero)
  +  perform the zoom (if the zoom size is > 1)
  +  wait for the 2nd interval (may be zero)
  +  wait for the standard interval specified in the Slide Show dialog
  +  do the transition to the next image

Bookmarks  (Gallery View > Bookmarks)

Assign names ("bookmarks") to chosen gallery locations (directory and image file), keep in a list, and use the list to select a name and go instantly to the associated gallery position. There are two parts: an edit dialog to build the list of bookmarks, and a [GoTo] button in the gallery view to show the bookmarks and select a location to go to. To assign new bookmarks, press the [GoTo] button and then select [Edit Bookmarks] in the dialog that follows. The Edit Bookmarks dialog is started. Click on a gallery thumbnail to add this location to the bookmark list. The assigned bookmark name will default to the file name. This name appears in an edit field where you can assign a better name. If you select an existing bookmark with a mouse click, its name is shown in the input field. You can change the name or press [delete] to remove the bookmark. New bookmarks are inserted at the last bookmark location selected. To go to a bookmark, press the [GoTo] button. The list of bookmarks is shown. Click on an entry to go there.
Gallery View Buttons 
Zoom-in / zoom-out. Increase or decreast the gallery thumbnail size.
If decreased to zero, the gallery becomes a simple list of file names.
Sort the gallery thumbnails in an alternative sequence. You can sort by file name (default), Photo date/time (from EXIF data), or file modification date/time (file creation or last modification date/time). The sequence may be ascending or descending.

Jump to the beginning or end of the gallery.
Scroll back (up) or forward (down) by one gallery page.
Sort Restrictions
An Album gallery can be sorted, but cannot be edited when in an out-of-order condition. To edit a sorted album, open the album again so that its natural sequence is restored.

A Metadata Report (Search Images with report type = metadata) cannot be sorted, because the association between the images and their metadata would be lost. You can get around this as follows: Run Search Images with report type = gallery. Sort this report as wanted (e.g. photo date descending). Run Search Images again, with report type = metadata and 'current set only' as the source of images to search.


Combine Menu (File View > Combine)
High Dynamic Range (File View > Combine > High Dynamic Range) (HDR)  
Combine (overlay) multiple images of the same subject with different exposure levels. The combined image can show improved visibility of detail in both the darker and brighter areas, in effect using pixels from the brighter images for the darker areas, and from the darker images for the brighter areas. Many digital cameras do exposure bracketing: take multiple shots in quick succession with different exposure levels. You can combine such images to make a better one. If the camera is adjusted manually between shots, take care to keep it level and aim at the same distant point. Some misalignment of the input images can be tolerated. If things move between shots, ghosting cannot be avoided.

Select the HDR menu function and select up to 9 images (link), which must all have nearly the same pixel dimensions. The images are aligned and combined automatically. This needs 10 seconds to a minute or more per image, depending on image size and CPU speed. When done, the combined image is shown, along with a dialog for manual adjustments. The contributions from the input images are hown as a series of editable curves. The horizontal scale represents pixel brightness, from dark to bright. Each curve represents an image which contributes to the pixels. The image contribution at a given brightness level is proportional to the height of its curve at that level. The initial curve for the brightest image will be high on the left and low on the right, meaning a high contribution to dark pixels and a low contribution to bright pixels. The darkest image will be low on the left and high on the right, and the remaining images will be in-between. The curves can be edited by dragging them with the mouse. The corresponding image contributions are changed accordingly, and you can see the results in quasi-real-time in the output image. In general, the brightest image should have a higher contribution to the darker pixels, and the darkest image a higher contribution to the brighter pixels. You will likely need practice to become effective at working the curves. A faster and easier alternative may work as well: after the images are combined, ignore the curves and exit from HDR. Use various edit functions to refine the image: Brightness Distribution, Retouch Combo, and Tone Mapping. Select Area can be used to enclose any area in the image which needs more brightness, color, or local contrast, so you can apply different methods and parameters to different areas.
High Depth of Field (File View > Combine > High Depth of Field) (HDF)
Combine (overlay) multiple photos of the same subject with different focus settings from close to distant. Different parts of the subject are in sharp focus in each image. Combine the images so that all parts of the subject are sharp. This technique is most useful for extreme close-ups.

Making the photos: choose a point for the center of the image. Aim the camera at a near object and depress the shutter button 1/2 way to set the focus on this object. Hold the button at the 1/2 position, aim the camera at the chosen center, and snap the photo. Now choose a farther object and do the same. Repeat with increasing focus distance. Hopefully each part of the subject is sharp in at least one photo. The camera position should be very nearly the same for all photos, which can be a challenge when the subject is very close. Camera movement can cause scaling and parallax problems (close objects shifted against distant objects). Such problems may be fixable later in Fotoxx, but this may require considerable time. It is better to avoid the problems.
Processing the photos: in Fotoxx, choose the HDF menu function and select up to 9 images (link). The images will now be aligned as well as possible. This needs 10 seconds to a minute or more per image, depending on image size and CPU speed. The output image is an even mix of the aligned input images. A small amount of camera movement between the photos is compensated, but this is limited, and parallax shifts are not compensated at all. When the alignment is complete, a dialog opens. You can select any input image and "paint" with the mouse on any area of the output image. This converts the original image mix to the single selected image for the area being painted. For each area or object in the image, choose an input image that is sharp in that area. The radius of the paintbrush can set larger or smaller, so you can paint large areas quickly and control fine detail when needed. If you have overlapping near and far objects, time and patience will be needed to make all of them sharp. Misalignments can be corrected by selecting the warp option in the dialog. The underlying images can then be dragged and warped with the mouse, and the composite output image is changed accordingly. The warp is limited to the area around the mouse. When a painted area is dragged, the corresponding image is automatically selected and dragged, while areas painted with other images remain fixed. Areas that have not been painted cannot be dragged. Move around to different areas and make incremental drags until all areas are aligned. 

Suggested Workflow: Using paint mode, choose each image in sequence and paint all areas that look sharp in that image. Any boundaries that are not well-aligned will show up clearly as shifts in the edges of objects in the image. Some of these can be made unimportant by changing the image used for painting (if more than one image is sharp enough). Using warp mode, make fine adjustments as needed to eliminate visible shifts.
Stack/Paint (File View > Combine > Stack/Paint)

Stack (overlay) multiple photos of the same subject taken at different times. Remove tourists and cars that come and go between shots.

Making the photos: Aim the camera at the same distant point and take multiple photos as tourists or cars move in front of the subject. Try to get two or more photos for each area of the subject not obstructed by the transient objects. Hold the camera steady and aim at the same point, so that the images will align accurately.

Processing the photos: In Fotoxx, choose the Stack/Paint menu function and select up to 9 images (link). The images will now be aligned as well as possible. This may need a minute or more per image, depending on image size and CPU speed. The output image (lower left) is an even mix of the aligned input images (top row). When the alignment is complete, the dialog shown above starts. You can select any input image and "paint" with the mouse on any area of the output image. The single selected image is used for area being painted. For each area in the image, choose an input image that is free from the transient objects. The radius of the paintbrush can set larger or smaller, so you can paint large areas quickly and control fine detail when needed.
Automatic operation
: press the [Hide] button to see if transient objects can be removed automatically. This will work for areas in the image where multiple photos of the unobstructed background are available (lower middle image). To show all of the transient objects, press the [Show] button (lower right image). This generally works, but not perfectly. Slight image misalignments or lighting differences (esp. moving shadows) may cause the algorithm to select background pixels instead of foreground pixels. You can use the paint method described above to repair the errors manually.
Stack/Noise (File View > Combine > Stack/Noise)

This function combines 2-9 images (photos) of the same subject. The photos should be nearly the same, except for small offsets caused by a hand-held camera. If the photos were made with a very high ISO setting (low light conditions), the pixels will have considerable noise. By making many photos and averaging them, the noise can be mostly eliminated.
Making the photos: Choose a point for the center of the image. Take several photos using the same center and being careful not to shift or rotate the camera too much. The more photos the better. Up to nine can be used with Fotoxx, but you can take more in order to have some to discard if they are not sharp, a common problem with low light conditions and long exposure times.
In Fotoxx, chose the Stack/Noise function and select up to nine images (link). They will be combined automatically and shown, and then a dialog will open. The initial output image is a combination of all the selected input images, averaged together. This means that the RGB values for each output pixel are the average of the RGB values for the corresponding input pixels. A few alternative tools can be used to possibly reduce the remaining noise a little more. The use median button will change the output pixels from an average of the input pixels to the median of the input pixels (1-3 middle RGB values are averaged, depending on the number of images). This may or may not be better, so switch back and forth to compare (the screen update may need several seconds). The checkboxes for omit low pixel and omit high pixel will cause the lowest and highest RGB input values to be discarded before the average is calculated. This may help to get noise spikes removed from the mix. This has no effect if the median method is selected.
Panorama Image (File View > Combine > Panorama)

This function stitches 2-4 images together to make a wide-angle image or panorama. The images must overlap by 15% or more, so that the program can find where they match and join them together. Start by selecting 2-4 image files (link). The images are initially joined and shown with a small transparent overlap. A pre-align dialog (above) asks you to drag the images into rough alignment. Drag the images into the correct left to right order. The image to drag may overlap other images. To be clear about which image is being dragged, drag from near the center of the image. After the images are in the correct order, align each image to its left neighbor. It works best to proceed from left to right. Move an image horizontally and vertically into rough alignment with its neighbor to the left, then rotate the image if needed by dragging the bottom edge left or right - the image pivots around the mid-point of its overlap with the image to the left. The fastest method is to align the overlap middle region first, then rotate the right image if needed to bring the upper and lower overlap regions into alignment. Extreme accuracy is not needed. Use the [resize] button to get a bigger combined image after moving them closer together. The images should be correctly curved and fit together well. If they do not, then the lens mm parameter (focal length, 35mm equivalent) needs adjustment. The curvature of the images changes as lens mm is adjusted. The initial value is obtained from the EXIF data if available, and this is normally good enough. You can measure and set lens mm manually using the [search] button described below. If the images have no curvature (e.g. scanned images), use the no curve checkbox to set the lens mm effectively to infinity.

If an image was trimmed so that the greater dimension (width or height) was reduced, then the EXIF focal length is no longer valid, and the EXIF initial value may not work well. A section of an image taken from the middle has an effective focal length greater than the original. Increase the lens mm parameter until the images fit together reasonably well, or use the [search] button to make a more precise determination (described below).

The no auto warp checkbox is normally unchecked. Its purpose is described below.

The manual align checkbox will use the manual pre-alignment as the final alignment. This is for images that have no clear features to match and align the images automatically.

Press [proceed] when pre-alignment is finished, and the program will do fine alignment and join the images. Internally, the images are shifted and rotated and the degree of match is evaluated. This is done with increasing image sizes until the best match is found. This may need a minute or more for a weak PC working with large images. You can speed up the process greatly if you reduce the input images to 1/2 size. Do this also if the process fails for lack of memory. Panoramas with 4 large images can require 2+ GB of memory during processing.

When fine alignment is complete, the combined image is displayed. The dialog shown here is started, for fine adjustment of brightness and color match. You may see a sharp border between images if the images do not have the same brightness and color balance. The [auto color] button can be used to perform an automatic color match, which is often satisfactory by itself. Use this button multiple times to get improved matching at the expense of greater color shifts that could add a false color tint. Restore the original image colors with [file color]. The image selected with the Select Image radio buttons is the starting image for the auto color matching. Reset using [file color] and select a different starting image to see results that may be slightly different. The brightness and RGB color controls allow you to make additional changes to better match the images. Select one of the images with the radio buttons, change the values for brightness and color, and press the [apply] button to see the results. Use [auto color] to match the other images to the one changed. Use [file color] to restore the original values from the input images. The blend width input governs how the images are blended together: at the image joints, the color balance is gradually shifted over this many pixels, to mask imbalances that cannot be fully corrected. The default is 1 pixel, which makes any brightness or color differences look obvious.

If the images do not align perfectly, you may be able to improve the alignment by using the mouse to push the images into alignment. In the final dialog, select mouse warp, select which one of the images with the radio buttons, and then drag the mouse carefully along the edge of the image where it should align with its neighbor, and move the image into alignment. The image is moved locally around the mouse while more distant parts stay fixed. Parallax shifting will require a compromise, since it is generally not possible to keep both foreground and background in alignment.

The flatten image control can be used to "unbend" the image, which will straighten curved lines (e.g. buildings may look curved). A value of zero has no effect and a value of 1.0 will fully flatten the image.

When done, you can use unbend, warp, trim/rotate and other functions for final adjustments.

Vertical Panorama
(File View > Combine > Vertical Panorama)
This function works the same as horizontal panorama, except that the images are arranged vertically. To change the order of the images, drag them from near their centers. To rotate an image, drag the right edge up or down. It works best to align from the top down.
Panorama Notes
Scanned images can be combined if there is enough overlap. Check "no curve" since there is no curvature.
Auto Warping
The images are slightly warped in various directions during alignment to find the best match. This is to compensate for shifts in camera horizon or rotation, causing image distortions that reduce the quality of fit. If the overlap area of two images includes a large object that moved in or out between the two photos, the alignment process may go crazy trying to match the images, resulting in alignment that is very poor. By selecting no auto warp you may be able to get the alignment to succeed or have only a small error. Another option is to select manual align.
Setting lens mm Automatically
The [search] button in the panorama pre-alignment dialog initiates an automated search for optimum lens mm. Use a suitable image pair: the subject is 50+ meters away, the images have a low horizon difference and little relative rotation, and there is plenty of high-contrast detail in the overlap area. Input your nominal lens focal length for lens_mm. After doing a decent pre-align, press the [search] button and wait a while for the results. Do this a second time and observe the change. If lens mm remains consistent, you can use it for your panoramas. The search function steps through a range of values for lens_mm and the image alignment offsets for x, y, and theta. It searches for the lens value that give the best alignment results for the given images. The process needs a minute or more, but you only need to do this once to characterize a given camera lens and focal length (zoom setting). Use the [save] button in the 1st dialog to put the focal length back into the image EXIF data.
Setting lens mm Manually
Make a panorama image of a brick wall (or any wall with lots of detail). The wall should be 5+ meters away. Take two photos with about 40% overlap. Within the panorama pre-align process, adjust lens_mm until overlapping bricks coincide. When making the two images, be sure to turn the camera on a vertical axis through the lens, minimizing lateral movement and rotation in other axes - otherwise your lens mm may not be optimal. The result should roughly correspond to the nominal focal length of your lens (35mm equivalent). It may be off somewhat (my 27mm lens works best with a lens_mm setting of 29-30mm). I speculate that this is because wide-angle camera lenses are not ideal lenses (pinhole equivalent). Most panoramas will still work well even if the lens_mm setting is off by 10%.
Color Matching Problems
If the images in a panorama have a large brightness difference, the automatic color matching may not work well enough. The most common problem is false sky colors. You may be able to improve this by brightening or darkening an input image to more closely match its neighbors. Sky can be easy to fix by selecting the false areas and copying sky from elsewhere in the image (Clone Image). It seems to work better if you brighten the darker image instead of darkening the brighter one. You can do this in the final dialog as described above, or you can do this before starting the panorama.
Panorama Limitations
Panoramas including nearby objects can be tricky: when the photos are made, be careful to turn the camera on an axis through the lens, with minimum lateral movement, otherwise the images may align poorly because foreground objects are shifted against the background (parallax). This is not an issue when the subject is 50+ meters away, since a small lateral movement has little impact on the image. Keep the camera level to avoid a large vertical shift (horizon shift), which can cause image distortions that may not be fully corrected. Avoid rotating the camera for the same reason.

PT Panorama
(File View > Combine > PT Panorama)
The Panorama Tools utilities (via the Hugin package) have been integrated into Fotoxx under the menu PT Panorama. The user interface is very simple: select (link) the input images in any order and proceed. Everything else is automatic. After a minute or so the finished panorama is shown and is now the current file in Fotoxx. The file name is <first input file name>-PT.tif. This is an 8-bit TIF file and is very large. You can save the file as JPEG and delete the original TIF to save space. Panorama Tools usually does a fine job, but I have noticed minor alignment errors in some cases, usually too small to notice. It may be possible to eliminate these by using the full features of Hugin directly instead of the automated script used in Fotoxx. They may also be fixed using Mashup - see the related paragraph in Mashup, below.

Select many images and automatically join them into a compact format. This is a fast and easy alternative to Mashup, which is harder to use but offers more flexibility to vary the size and position of each image.

The first dialog is shown at upper left. Frame Width is the width of the frame image that will be created. The height is determined by the number of selected image files and the space required. Frame Margin is the margin size (pixels) around the frame image. Image Columns specifies the number of columns in the frame image (6 in the above example). The number of rows is determined by the number of image files selected. Image Margin is the space between images (pixels). Select the image files to combine (link). Press Proceed when done. The resulting image will be made in a few seconds (or up to a minute for hundreds of images). This image will typically have a very uneven bottom margin, as shown by the top image above.

The Optimize dialog begins automatically. It can rearrange the images so that the bottom margin is more even. Press Start and wait for the image to optimize. You can watch the progress. The function will exit if an optimum is found that makes the bottom margin even within 2 pixels. It may continue to search indefinitely if this goal is not reached. Press Stop to force the optimize function to exit with the best solution found so far. If optimization is successful, you will get even columns as shown in the lower image.
If the bottom edge is still uneven after optimization, you will be asked if you want to add margins to some of the images to make the bottom edge even. This will result in an even bottom edge, but the inside margins will no longer be even.

: Optimization works best if the number of images is divisible by the column count, i,e, the same number of images in all columns. It also works better if the number of images per column is at least four (better more). This gives the optimizer enough flexibility to find a solution with an even bottom edge.

The last dialog appears, shown at lower left. You must now assign a unique name to your montage, one that does not conflict with other montages you have made before. A file save dialog is started, and you can save the new montage file anywhere you wish. If the map option is selected, a map of the included images is also created. This map allows you to click on any image in the montage to get a larger popup image which can be zoomed up to the full size of the original image, using the mouse wheel or F11. This will work now and at any time later, even if the montage file is moved, presuming the map file and the original images are still available. The saved montage file is given a special suffix to make it recognizable as a Fotoxx montage file.

The full montage file name is: your-assigned-name (fotoxx montage).jpg.
(if the map option is not selected, then "(fotoxx montage)" is not included in the name).
The map files are stored in  ~/.fotoxx/montage_maps/.

Note that the popup image feature is not standard. It will not work outside of Fotoxx.

Mashup (File View > Combine > Mashup)

Arrange multiple images and text in a layout. Images can be added, resized, rotated and moved around by dragging with the mouse. Images can be made entirely or partly transparent in selected areas. Text can be added, moved, resized and rotated. Text attributes can be specified: font, size, color, outline, shadow, transparency.  Lines and arrows can be added. The example here shows some of the possibilities.

In the first Mashup dialog, choose a background or layout image where other images will be placed. Choose an existing image or create a new monotone image with a specified size and color. You may also open a previously saved mashup project and continue editing.

The 2nd Mashup dialog is a choice: edit images, edit text, edit lines and arrows, rescale to a larger size, save the completed composite image (Done) or abandon the image (Cancel). The first three choices lead to dialogs to perform the respective edits. Each of these return to this dialog when done, so you can add or modify images, text, and lines/arrows in any sequence. Rescale is explained below.

Use this dialog to select and place images on the layout and revise their appearance: size, rotation, position, and transparency. An image may be partly or wholly transparent, overall or within specified areas. This means that the background image or an overlapped image can show through the transparent areas. The Add button leads to a gallery file selection dialog (link). Selected images are placed on the layout. After the images are added, click on any image to select it for modifications.  Drag the image from the middle to reposition the image in the layout. Drag the lower right corner to resize the image. Use the dialog controls to adjust the image. The dialog controls operate on the last image added, clicked or dragged. The Next button will cycle through the images one at a time, flashing the selected image. This can be used when overlapped images make it difficult to select the desired image by clicking it. Scale resizes the image. Angle rotates the image. The Stacking Order buttons raise or lower an image relative to other images - this determines which of two overlapping image will be on top. Base Transparency is used to make an entire image partly transparent. The [paint] button is used to make any part of an image partly or fully transparent, using the Paint dialog below. The [warp] button is used to bend or warp an image, using the Warp dialog below. The black margins checkbox can be used to remove black margins left by other edit functions, e.g. warp. These will be made transparent. The Margins controls can be used to increase edge margins. The Hard margins cut off  image edges. The Blend margins make the edges partly transparent to blend them into the background or overlapped images.

"Paint" more or less transparency for selected image areas. Click on an image to select it. The mouse will have a circle around it to show the range of action. Use radius to adjust the size of the circle. Left-drag the mouse over the image to make it transparent in the areas covered by the circle. Right-drag to make it opaque. If Gradual is checked, transparency changes are made slowly as the mouse is dragged. Specify a power value for the mouse center and edges to make the changes faster or slower.

Click this dialog to insure it is active, and click on an image to select it. Drag the image with the mouse - the image will warp or stretch locally in the direction of the mouse (like sheet rubber). The area of warping is roughly given by warp span, which is a fraction of the image size. Each drag is a step that adds to previous steps. Recent steps can be reversed with [undo last], and the unbent image can be restored with [undo all].

The Edit Text dialog is used for placing text on the layout. Enter some text and press Add. You are asked to click on the layout where the text will be added. Drag it into position, then use the dialog controls to set font, size, color, angle, background color, outline size and color, shadow size and color, and transparencies for each of these. Drag the text to a new position at any time. Click on any existing text to show its properties in the dialog and revise them. Click on a text and press Delete to remove it. When done editing, press Done to return to the 2nd Mashup dialog.

The Edit Line/Arrow dialog is used for placing lines or arrows on the layout. It works very much like adding text. Enter a length and width and press Add. You are asked to click on the layout where the line will be added. A line is placed on the layout, or an arrow if one of the Arrow head options is checked. Drag the line/arrow to the desired position. Adjust length, width, angle and attributes (background, outline, shadow) using the dialog. You can also drag either end of the line/arrow to reposition that end while leaving the other end fixed.
You can use the mouse to move and resize objects in the layout:
  +  click the object to select it - it flashes to confirm the selection.
  +  drag from the approximate center to reposition the object.
  +  drag the image or text lower right corner to resize.
  +  for a line/arrow, drag either end to move that end only.

The keyboard arrow keys can also be used to move the currently selected object in 1-pixel steps.

You can also add images saved by Select Area. In the Edit Images dialog, press [Add] to start the file selection dialog. Use the [Top] button in the gallery window, select HOME, then select .fotoxx/saved_areas. Open any of the .png images found there. The original area outline is used, and edge blending works from these edges.
Mashup project files
You can save a project and open it later to continue editing. However, the project file will open successfully only if the layout image and all the overlay images are still available in their original locations. The Mashup project is rebuilt using these images and some saved metadata that is in the project file: image and text locations, scales, transparency, etc.
Mashup Rescale
Working with a very large layout (over 20 megapixels) can be quite slow, especially if the PC is not very strong. Dragging a large overlay image can be slow and jerky. You can work much faster if you use a smaller layout to build the project, and then make it larger after you are finished. There is no loss of resolution in the final image, since the overlay images and text are regenerated from the inputs (e.g. an image that was scaled to 0.2x in the initial layout is rescaled to 0.6x if the layout is magnified by 3x). The original full size image file is used for this rescale. The Rescale button allows you to magnify the project by 2x, 3x or 4x (4x, 9x or 16x by area). There is also a reset option to restore the original smaller project size. With this method, you can work with a 10 megapixel layout and resize it up to 160 megapixels when done. The larger layout can still be worked on directly afterwards, but it will be much slower.
PT Panorama Fix
Mashup can be used to fix minor alignment offsets from PT Panorama. After running PT Panorama, start Mashup (in the same Fotoxx session), and create a flat layout image with a good size for editing (e.g. 3000 pixels wide). Start the dialog for adding images to the layout. Navigate to the directory /tmp/fotoxx-xxx/ where you will find the images left by PT Panorama. They have been color matched and warped to fit together. Add these images to the layout. Check the box to make the black margins transparent. Resize them to fill the layout (all must have the same scale) and move them around to fit together. Zoom the window larger for precise alignment and align the images as well as possible. Small misalignments will persist if the images do not fit perfectly. There may also be brightness or color mismatches at the image edges, but these can be fixed later. Start the Warp Images dialog. Drag the mouse in small steps over a misaligned area to move an image into alignment with its neighbor. Use a small span (e.g. 0.1) to insure that correcting one misalignment does not create others elsewhere. Several cycles of dragging the images in several locations may be needed, but with patience you can make the alignments perfect. If there are visible brightness or color mismatches at image edges, blend these together using the margin blend controls. This should be done only after the alignment has been perfected - otherwise this will cause blurring where the images do not align, making alignment corrections harder to see and control. Lastly, rescale the layout to a larger size if wanted. This does not lose resolution, since the input images are rescaled and the warps are rescaled and re-applied.

Process Menu (Gallery View > Process)
Batch Convert Files (Gallery View > Process > Batch Convert)
This function is used to rename, convert, resize, upright and move multiple image files at once. An overlay image can also be added at a selected position (e.g. a title, credit line or copyright notice).

Select Files
Select files to convert from a gallery window (link).
New Name
Optional new name with optional inserted text (photo date, sequence number)
Sequence Numbers
Starting sequence number and adder for each output file.
New Location
Optional new directory location for the converted files.
new file type
File type for converted images, or "no change".
max. width, height
Output images will fit within these dimensions (ratio is not changed).
delete originals
Delete the input files after successful conversion.
copy metadata
Copy all EXIF and IPTC metadata to the output files.
If an image is rotated 90 degrees, upright it (if status known from EXIF).
Sharpen output images using the two supplied parameters
Overlay Image
Add an overlay image at a selected position in the output images. See below.
Make constant size
Make the visual overlay size independent of image dimensions. See Below

The new file name may have inserted text: a photo date (from EXIF metadata), a sequence number, or the original file name. Specify what and where to insert with the following text:
The original file name is inserted here
A running sequence number is inserted here. See below.
 $yyyy $mm $dd
The photo date (year, month, day) is inserted at these positions

Example: San Francisco $yyyy-$mm-$dd $oldname $sss
The input image file "Golden Gate Bridge.jpg", with a photo date of May 12, 2014, would convert
to the following output file name: "San Francisco 2014-05-12 Golden Gate Bridge 123.jpg".

For the "$s..." plugin, specify the length of the field with the number of 's' characters. Leading zeros are added for sequence numbers with fewer digits. Sequence numbers not fitting in the specified length will be as long as needed. Keep in mind that the file name sort order in the galleries is strictly ascii order, so the sequence of numbers 1, 2 ... 9, 10 will sort as 1, 10, 2 ... 9 (if these are leading characters in the file names). You can keep the numeric order by specifying a field lenght of 2 (in this case), resulting in the sequence 01, 02 ... 09, 10. 

Either "$oldname" or "$s..." must be present to insure output file names are unique.
If New Location is missing or unchanged, delete originals is ignored.
If an output file already exists, the input file is not converted.
For an explanation of the sharpen parameters, see the Sharpen function.

Overlay Image
A small overlay image can be added at a selected position in all the output images. Use the Open button to select the image file. The overlay image will be scaled to Width percent of the output image width. The position is selected by clicking one of the Position buttons. If Make constant size is checked, the visual size of the overlay image will be made constant for the selected screen or window dimensions. Without this, a "tall" image that displays with left and right margins would have a visually smaller overlay.

An overlay image can be used to add a title, credit line or copyright to the converted output images. Prepare the overlay image as follows: Use New Blank Image to create a base image to hold the text. The scale does not matter, so make it larger than needed, say 1000 pixels wide. Use Paint Transparency to paint the entire base image transparent. Use Add Text to put the desired text on the base image, using the font, color, and other attributes as desired. Scale the text to fill most of the base image. The text is visible and the base image (background) is transparent. Use Trim to remove excess margins if needed. Save the final image; a convenient location is  ~/.fotoxx/saved_areas, but any directory can be used. This image is now ready to use as an overlay image for Batch Convert.

If image files are renamed or moved using Batch Convert, and if deletion of the original image files was also specified, then all albums containing any of the input files are updated to reflect the new names and locations.

Preserving File Sequence
If you use a leading sequence number, the input file sequence will be preserved at the output location. Thus you can select image files in any order, or use an album with ordered images, and preserve this sequence in the output.
Batch Upright (Gallery View > Process > Batch Upright)

This function works like Batch Convert Files but only does the upright function. It uprights image files rotated 90 degrees. It depends on EXIF data to know if a file is rotated. It is much faster than Batch Convert Files. You can simply select all candidate files and let it find the ones that are rotated. The search speed is about 3000 image files per minute on a strong PC. There are two options to specify the files to search. Select Files leads to a gallery file selection dialog (link). Survey all files will check all image files in your database and upright those that are rotated.
Batch Delete/Trash (Gallery View > Process > Delete/Trash)

Select files from a gallery (link).
Select the option to delete or move to trash.
Batch RAW (Gallery View > Process > Batch RAW)
Batch Raw Therapee (Gallery View > Process > Batch Raw Therapee)

These functions convert selected RAW image files to JPEG, PNG-8, PNG-16, TIFF-8 or TIFF-16 format, using the library program libraw or the application program Raw Therapee. The PNG and TIFF formats have either 8 or 16 bits per color. RAW files generally have 10-12 bits per color, and noise beyond that. Therefore use a 16-bit format to keep all of the data available from a RAW file. The difference between 8- and 16-bit color is rarely visible, but a higher color depth provides a greater margin for retouch functions that can radically shift the brightness distribution, causing a problem known as "banding" or "posterization".

Use the [Select Files] button to choose one or more RAW image files from a gallery window (link). Choose one of the output formats. Choose one of the downsize options if wanted, and set the auto sharpen parameters if wanted. See the Sharpen function for an explanation of these parameters.

The image files are converted one at a time and displayed in the main window. Depending on the number of files, this can take a long time (a strong PC does about 40 files per minute for most RAW file types and TIFF-16 output). PNG-16 produces much smaller files than TIFF-16 because the files are compressed (with no quality loss). This also needs more time to do the compression work.
Script Files (Gallery View > Process > Script Files)

Script files allow you to define a set of edits once, and carry them out on as many image files as you wish. This can be useful when many photos of the same subject were made under the same lighting. You can choose one photo and edit it to perfection, recording every function used and adjustment made in the dialogs and curves. Then you can apply these edits to the entire batch of photos. Certainly this will not be as good as editing each photo individually, but it is much faster, and you can always go back and make additional adjustments after viewing the results.

Press [start] to begin a new script file. You will be asked to choose a file name for the script. Now choose an image file and perform your edits. After each edit function is done, a message appears to confirm its addition to the script. All the dialog inputs and curve edits are now saved in the script file. After the last edit, open the script menu again and choose [close] to complete the script.

To execute a script, open the script menu and choose [select]. This is the standard file selection dialog (link). Select the files to edit using the script. Now choose [run]. You will be asked to select a script file to execute. The script starts up and processes all the image files in sequence. You can watch the action as the images fly past. All modified images are saved as new versions, so the original files are not lost. Those you decide you no longer need can be quickly removed using the Batch Delete/Trash function.

If RAW files are processed, the corresponding outputs are TIF-16 files.

Not all edit functions are scriptable. Some edit functions use mouse drags on the image, e.g. Trim/Rotate and all warping functions. These are not scriptable. If you try to use one of these while building the script, you are told this is not possible.

The following functions are currently scriptable. Others are possible but have not been converted for scripting. If there is a need for some function not included, contact me.
Retouch Combo Brightness/Contrast/Color adjustments
Adjust Brightness Dist. Reshape the brightness distribution
Zonal Flatten Enhance dark areas with low contrast
Tone Mapping Enhance local contrast where weak
Resize Specify width/height or ratio (e.g. 1/2)
Voodoo1 Automatic enhance
Voodoo2 Automatic enhance
Flip Image
Flip or mirror image horizontally or vertically
Sharpen fuzzy edges
Blur Blur image
Reduce image noise
Color Mode
Make image B&W or color, positive or negative, or sepia
Shift Colors Tune colors using a slider
Color Saturation
Change color saturation (intensity)
Adjust RGB/CMY Tune colors using RGB or CMY sliders
Color Profile
Change the color profile, e.g. Adobe RGB <-> sRGB
Color Depth
Reduce the color depth (bits/color) for "poster" effect
Pencil Sketch
Convert image to simulated pencil sketch
Convert image to a cartoon
Line Drawing
Convert image to a color line drawing
Color Drawing
Convert image to a color drawing
Graduated Blur
"Soften" the image while retaining details
Add a 3D relief effect to an image
Convert an image to tiles
Convert an image to dots (Roy Lichtenstein effect)
Convert image to a simulated painting
Add texture to an image (e.g. image on a rug)
Add a pattern to an image (e.g. image on a brick wall)
Custom Kernel
Apply a custom convolution kernel to the image
Alien Colors
Add strange coloring to an image

Burn Images to DVD/BRD (Gallery View > Process > Burn Images to DVD/BRD)

Select any number of image files and copy ("burn") them to a DVD or BlueRay optical disc.
  1. Insert a blank disc and wait for the initial clatter to finish. A message may appear asking you what to do with the blank disc, or a program may start which the window manager thinks you want to run. Dismiss this window or program.
  2. Start the Fotoxx Burn function after step 1 is complete.
  3. The Select Files button starts a dialog for selecting the image files to be copied (link).
    Select any image files, but stay within the capacity of the disc (DVD 4.7 GB, BRD 25 GB).
  4. Select a DVD/BRD disc drive to use from the drop-down list (even if there is only one).
  5. Press the Start button. The list of selected image files is sent to growisofs.
    This is an optical disc recording utility used by K3b, Brasero, and others.
  6. Progress is shown in a popup window, along with any growisofs error messages.
    The job will fail right away if the selected files do not fit on the selected disc.
The resulting disc is frozen. Leftover space cannot be used later to add more images.

Find Duplicate Images (Gallery View > Process > Find Duplicate Images)

This function is used to find duplicated image files anywhere within your image database. A duplicate image file can be an image file that exactly duplicates another image file, or an image file that "almost" duplicates another. For the sake of speed, thumbnail images are compared in memory. Hence it is possible that identical thumbnails are found for which the main images have some minor (likely invisible) differences that do not show up in the thumbnails. An image copy that was reduced to 1/2 size is likely be classified as a duplicate. The thumbnail size can be set from 32 to 256 pixels (max. width or height). A larger size reduces the probability of false positives. The thumbnail size greatly affects the amount of main memory required - e.g. for 100K images, size 32 needs 220 MB, whereas size 64 needs 880 MB. The memory required is roughly size x size x 0.75 x 3 x (image count). Two parameters are used to set the sensitivity for detection of identical or nearly identical images: pixel difference is the RGB value difference below which pixels are considered equal. Set to 1 to detect any pixel difference. pixel count is the number of different pixels below which two images are classified as duplicates. Example: if pixel difference = 3 and pixel count = 100, then images are classified as duplicates if fewer than 100 pixels are different by less than 3. The output is a gallery view, showing each set of duplicate images. Screening 8K images needs about 16 seconds on a strong PC.

Export File List  (Gallery View > Process > Export File List)

This function is used to create a file containing a list of image files. These are fully qualified file names, one per line in the text output file. This has no use inside Fotoxx. If you need to select images to feed into a shell script or another program, this is the way. The Select Files button starts a dialog for selecting the image files (link). Use the Browse button to select or define the output file.

Export Image Files (Gallery View > Process > Export Image Files)

This function copies selected image files into another directory. This would be typically used for copying files to a thumb drive, uploading files to a photo web service, etc. Select any number of image files by clicking gallery thumbnails (link). Select a directory where the image files will be copied. A limited set of metadata is also copied (relevant for a photo web services like Flickr). These are: photo date, keywords (tags), copyright, caption, comments, and geotag data (location).

Batch and search functions in the Metadata menu are duplicated here in the Process menu.

Map View Menus
There are two map view methods: World Map view and Net Map view. The differences are explained here.

World Map Menus

The World Maps functions use locally stored map files which can be downloaded as explained below. You can also install custom maps and use them like any other map.

Images by Map Location

If the separate package fotoxx-maps is installed, a set of geographic maps is available for Fotoxx. These are a world map and maps of each continent. Click the left side menu bar World Maps button to change to world map view mode. A world map is shown at first. Click on any area to get a much larger view of that area. The map image can then be panned and scrolled to any other area by dragging the mouse. Map markers (red dots) show locations having corresponding geotagged images. Click on a marker to get a gallery of images from that location. The window changes to the gallery view and the gallery appears. Press the world maps button and click a new location for a new gallery report.

Map Navigation
: zoom and pan/scroll for a map is slightly different from image files:
  +  mouse wheel forward: zoom the map to full size, centered on the mouse position
  +  mouse wheel backward: shrink the map to fit within the window
  +  left click on a marker: show gallery of images geotagged for that marked location
  +  left click NOT on a marker: zoom the map to full size, centered on the clicked position
  +  right click: shrink the map to fit within the window
  +  keyboard Z key: alternate between full size and shrink to fit
  +  mouse drag: the zoomed map image pans and scrolls like other images

When in world map mode, menus are available for choosing a new map and for searching images.

Choose Map

Choose Map allows you to choose any available map. All maps will show markers (red dots) where there are geotagged images. Click on a marker to get a gallery view of all the images at this location. The range of images selected corresponds to the marker size: images located within the marker area on the map are selected.

Installing Custom Map Files
Obtain the map from any suitable source, e.g. Google Maps or Open Street Map. You need to get the map as a JPEG or PNG file. You can use a screen capture function with Google Maps or OpenStreetMap. You can use the Fotoxx Mashup tool to stitch many maps together to make a huge map (e.g. 100 megapixels). These work well with Fotoxx pan and zoom. You can also use a scanner to capture one or more paper maps and accurately stitch them together with Mashup.

To install a map, put the map file into the directory /home/<user>/.fotoxx/user_maps. In this directory you will also need a text file: maps_index. Each map requires a line in this file which specifies the map file name and the latitude-longitude range of the map. Here is an example maps_index file:
   Hamburg.jpg,  53.455,  53.553,   9.906,  10.067
   Houston.jpg,  29.479,  30.053, -95.786, -94.905
The entries are map file name, low and high latitude, low and high longitude. All values are degrees, separated by commas. Spacing does not matter. Fotoxx assumes a Mercator projection, but this is not significant for maps covering less than 100 km (e.g. city maps).

If you make a custom map, getting accurate latitude and longitude values for the map edges can be tricky. Use the Open Street Map "export" option to view maps with an overlay rectangle labeled with latitude and longitude. Adjust the rectangle to match a corner of a map you have created and record the latitude and longitude values. You need accurate latitude and longitude data for the upper left and lower right corners of the completed map. The precision should be suitable for the scale of the map. 1 degree of latitude corresponds to about 110 km on the earth's surface. 0.001 degree corresponds to 110 meters.

Set Map Markers

Here you may choose to show markers for all images, or only images in the current gallery. You can use the latter capability to show markers for a chosen subset of images, e.g. images from particular file locations, from a particular vacation trip, having particular tags, etc. Use the Search and Album functions to select and screen images to produce the desired set in a gallery. The gallery can also be saved as an album for repeated use.

Net Map Menus

The Net Map functions use an internet service to provide maps from any location at any scale. The Net Map offers superior functionality, but depend on having a fast and reliable internet connection. Markers (red dots) will show the locations for any of your images with geotags. Use the mouse wheel or double-clicks to zoom-in on any location. Drag the map to change the center. Click on a marker to get a gallery view of the images at this location. The range of images selected corresponds to the marker size: images located within the marker area on the map are selected. The marker area varies with the map scale. Nearby markers on a large map will consolidate when the map is scaled back (zoomed out), and clicking the consolidated marker will get all the images of the contained markers.

Net Map Source

At this time, two internet map sources are supported: Mapnik and Mapbox. The default is Mapnik. It is entirely open and free and works quite well if your internet connection is good. The one drawback is that location names are in the language script of the location (e.g. Arabic, Chinese ...), so for Westerners these maps are only useful for Western countries using Latin script. Mapbox uses Latin script for all major location names. Mapbox, however, requires an access key, which you must request. These are free for modest usage: up to 50,000 "map tiles" per month, which is adequate for most purposes. To use Mapbox, go to the Mapbox web site, developers page, and follow the instructions. In Fotoxx, use the Net Map Source menu function and select mapbox. You must input your access key the first time only.

Net Map Locations

You can save a map location (map center and zoom level) with a given name, and recall the map location later with one click. To save a map location, navigate the map to a location and zoom-in to include what you want within the window. Enter the map location name and press the [Add] button. The new location is added to the list of available locations in the window. To recall a saved map location, simply click on the location name in the list. To delete a map location, click on the name and press the [Delete] button. A few map locations are included by default. You can keep or delete them.

The functions Images by Map Location and Set Map Markers are also available for Net Maps.   

Other Topics

Video Files
Video files (.mpeg, .mp4, etc.) may be mixed-in with your image files. They will show as image files in both file and gallery view. The image shown is the first frame of the video. In file view, you can click on the image to play the video in a separate window. Keyboard keys can be used to control this: 'space' to pause and resume, Escape or  'Q' to quit.

Web Service Photo Upload
There used to be a dedicated function to upload image files to Flickr, but this stopped working and was removed. It is actually not needed, since Flickr offers a capable upload service directly from the Flickr web site.
Most photo websites have the ability to upload multiple image files from a single directory, using only a web browser. Use one of the Fotoxx functions listed below to select and copy image files to the desktop or any other directory. From there, use the photo website's native browser interface to upload the image files.

Export Image Files - select image files from multiple locations and copy to a single output directory
Batch Convert - same functionality plus many more options
The first function is simple to use and can only downsize and copy image files.
The second function can also downsize and copy, but it has many more features:
  + rename the files (combine old and new names, sequence numbers, photo dates)
  + convert to another file type
  + upright images turned 90 degrees
  + remove metadata
  + sharpen
  + add an overlay image (e.g. copyright text) at designated position
Organizing Images for Efficient Searching 
Relevant links: Edit Metadata, Batch Add/Remove Tags, Batch Rename Tags, Batch GeotagsBatch Convert, Search Images, Image Locations, Images by Map Location, Index Image Files, Magage Albums, Slide Show.
The goal is to find all images for given criteria, e.g. photos of a given person at a given place and/or time range, all photos of a given person, photos from a specified location or event, etc. There are several ways to organize an image collection to accomplish this, with advantages and disadvantages you need to understand. The methods listed here (except for albums) are standards compliant and will work with other programs that support the same methods. These are (1) searching based on metadata (dates, ratings, tags (keywords), geotags (locations), captions and comments, and (2) searching based on file names or partial names, including directory (path) names.
Fotoxx can search using the following image metadata: photo date, rating (stars), tags (keywords), geotags (location names and earth coordinates), and text appearing in captions or comments. Searching based on file and directory names can also be combined with metadata searching. Any other metadata can also be searched, although not nearly as fast as the items listed, which are duplicated in a special index file for fast searching. A strong computer can search images for the listed metadata items and file names at a speed exceeding 50,000 images per second.

All of the search methods described below can be used in combination. The output of a search function can be the input of another search function (to further narrow the search), and search outputs can be added to prior searches.
The following is an overview of the different ways images can be made searchable.
Directory and File Names
These can be used as a basic organization that will enable you to find images even if more effective organizations (tags, captions) are not used. The highest physical organization should be by time, because this will naturally group photos together that are related. I suggest using one subdirectory per year named 2001, 2002, etc. This will also prevent any one subdirectory from getting too big. Optionally, image files may be further organized in time sequence by using MM.DD as the start of the file name. The rest of the name can be a topic or event, and a sequence number.
    Example:  /images/2011/08.20 Spitzbergen 23.jpg
This very basic organization allows Fotoxx to find files by searching for years and topics (file names). In the above example, a search for "spitzbergen" or even "spitz" will produce all the images of Spitzbergen. Years can be also be searched and combined with topic searches, e.g. "2012 Paris". The Batch Convert function lets you rename a batch of photos taken at one location or event by specifying a template name like this:
   "$mm.$dd Spitzbergen $ss"
Month and day (from the EXIF photo date) replace $mm and $dd. "Spitzbergen" replaces the camera file name (P00123456), and a sequence number replaces $ss.
Captions and Comments
A simple method of organization is to use captions and comments. These are arbitrary text strings that can be added to a series of images in rapid sequence: Start Edit Metadata, open an image, input some text, press [apply], press [next], input some text ...  Captions and comments are two separate inputs but treated logically the same. They are searchable: words appearing in captions and comments can be searched. You can specify persons, location, topic, etc. for each image and then find them again quickly.
(EXIF keywords)
The most powerful tool is tags, but this is also the most demanding of organizational care. You can go through your images sequentially and add tags by clicking on a list of defined tags. New tags can be defined as needed. Images can have many tags, and can be searched using AND/OR combinations of tags, also in combination with other criteria. Tagging is generally fast, needing a few seconds per image. Fotoxx has two methods of adding tags, a "managed" system and a "random" system. In the managed system, you define tag category names and the tags within each category. When adding tags to images, you can point and click from a list of tags organized by category and alphabetically within category. In the random system, you simply create tags as needed while you tag your images, following no particular system and without categories. When you enter the first few characers of a tag, existing tags that match these characters are shown in a pick-list which you can click to complete adding the tag. If there is no match, a new tag is created. Recently used tags are also shown in a list that can be clicked. Photos made at the same time will normally be tagged in sequence, and will also share many of the same tags. The recent tags list helps to speed the tagging process. Use Batch Add/Remove Tags to add the same tags to many images. Batch Rename Tags can be used to rename tags in selected (or all) images. Tags can be searched in any combination, combined with other search criteria such as a date range or location(s).

Note that images downloaded from the Internet may have many tags adhering to no system. You will need to clean these out or redo them to stop them from cluttering your list of defined tags. If you see undesired tags in your list of defined tags, it is easy to find the offending image files and purge or change their tags: use the Image Search function to find the images, using the unwanted tags as search criteria, and feed this list to Batch Add/Remove Tags or Batch Rename Tags. Tags from downloaded files will have no category, which keeps them separate from tags you define (if you are using the managed tags method). Still, you should avoid accumulating thousands of random tags, and it is easy enough to get rid of them whenever they appear.
Use geotags to assign a city or location and country to your images, and optionally latitude/longitude. This enables all images for a location to be quickly found. If you use a camera with a GPS receiver, geotags are added to the image EXIF data, and location searching is available automatically. Since image dates are also automatic (in EXIF), images can be searched by date range and location without you having to enter any data for each image. You can leave it at this, or add some of the above extras if you accept the extra effort required. My experience so far with in-camera GPS is that the location names are chaotic and you may want to sanitize them (mixed upper/lower case, with/without states or other political subdivisions, mixed languages, etc.). You can fix the mess with a little effort: search for the location name you want to change (e.g. MUENCHEN, BAYERN, DEUTSCHLAND), then process the resulting images with the Batch Geotags function to change the location name (e.g. Munich, Germany). Location names can be searched in any combination.

When you add geotags to an image manually, it is usually sufficient to enter just the city or location name and then press [Find]. If the location has been entered sometime in the past, it will be recalled and all geotag data will be filled-in automatically (city/location name, country, latitude, longitude). This will also work if only a few characters of the name is entered, e.g. "hono" will recall the data for Honolulu, if available. When a location is entered for the first time, enter the city or location name and the country, and press the [Web] button. A web service will usually find the latitude and longitude automatically. If not, you can use Wikipedia or other web services to find the location coordinates and enter them manually.

Images with geotags are also searchable by clicking markers on a world map. The markers are automatically added to the map for all images containing geotag coordinates. The map can be zoomed to any scale from street-level to planet level.
Another method of organization is to use Albums. Choose a name for each album and assign any desired images to the album by clicking thumbnails in gallery pages. The images are not duplicated: the album is simply an ordered list of file names. Albums can be selected by name and viewed as a gallery of thumbnails. These can be rearranged via thumbnail drag and drop. The images can then be viewed sequentially using keyboard arrow keys, randomly by clicking thumbnails, or as a slide show with animated transitions between images. Albums are also implemented in some other photo management apps, but each one is different and incompatible.

The image search function can be used to find images to start a new album, and then images can be added, removed, and rearranged as needed. Images can be added simply by clicking gallery thumbnails as you browse your image collection.

The following is a summary of some ways to organize a large image collection, with factors to consider when choosing which methods you want to use. In the list below, "search by" specifies which search criteria can be used with each option. Many of the methods below can be combined, and the possible search criteria increases accordingly. Searching by photo date (EXIF) is available with any organization.

Images Organized by Topic
Images Organized by Year and Topic
Images Organized by Year, Month, Day and Topic
Image Directory and File Names Contain Topics
Captions and Comments
Managed Tags
Random Tags
Translation files for Fotoxx are found here:  /usr/share/fotoxx/locales/translate-xx.po.gz
The file may or may not be compressed (.gz ending). xx is a standard 2-character language code (e.g. de for German) or a combination language and region code (e.g. de_AT for Austrian German). This code normally corresponds to the locale of the computer, as shown by the command echo $LANG. If there is no installed translation file for xx, you can use the dummy translation file for en (English) as a template. Replace the translations of english to english with english to new-language, and save the new file with the right xx code. The translation files are protected and cannot be edited unless you have root privileges. It is better to copy a translation file to a more convenient location for editing, and save the edited file in the standard location when ready to test. Translation files are available for use immediately - no conversion to a binary format is needed since the text files are processed directly by Fotoxx. However, it is advisable to go through the standard GNU translation process to find possible errors. This is explained below.

Translation files are commonly called ".po files" and have the file type ".po" (or ".po.gz" if compressed).
A typical translation in a .po file looks like this:
  msgid "The file name is: \n %s"
  msgstr "Der Dateiname ist: \n %s"

"msgid" is an English text for translation. "msgstr" is the translation (German in this case). The special codes "%s" and "\n" are for inserted text and formatting. A file name will be inserted at "%s", and "\n" starts a new line. In the example above, the displayed file name will start on a new line. In the translation (msgstr line), these codes must match the English codes (msgid line) in both type and sequence.

A missing translation looks like this:
  msgid "The file name is: %s \n"
  msgstr ""

Revising an existing translation
  1. Edit  translate-xx.po  to add or update translations for language "xx".
  2. Replace the original file in /usr/share/fotoxx/locales/
  3. Option: compile the .po file to check for errors: 
     $ msgfmt -v --check-format -o /dev/null translate-xx.po
  4. Run Fotoxx and check how the translations look. If the computer locale is not "xx", start Fotoxx in language "xx" with the command:  $ fotoxx -l xx
  5. Send the modified .po file to me  [contact]  so it can be included in Fotoxx release packages.
Step 3 is optional. The usual binary translation files (.mo) that are output by msgfmt are not needed by Fotoxx. The translation source files (.po) are read directly by Fotoxx, and changes made to a .po file are effective the next time Fotoxx is started. Step 3 is useful to find errors (e.g. missing or non-matching format codes, quote marks, etc.).

Whenever Fotoxx is started from a terminal, missing translations are listed in the terminal window. There is also a function for this: Tools > Missing Translations lists missing translations in a popup window.
Problems with long translations
English can be terse compared to other languages (e.g. "undo" is "Rückgängig machen" in German), and this can cause a confusing appearance in the GUI layouts. Therefore try to make dialog labels and buttons short, and look closely at the resulting GUI layout.
User Guide translation
The English user guide is normally found here:  /usr/share/fotoxx/data/
The file is a text HTML file, which may be edited with any HTML editor. This is a large document, so expect a week or more of work to translate it. In order to reduce the work, you can use a simple text editor and supply text without images - in this case I will convert to HTML and supply the images. If you make a new or revised translation, please send it to me  [contact]  so it can be included in future releases.
Recent Changes to User Guide
This section is provided to help you quickly review the changes in the user guide.
Fotoxx version numbers correspond to year and month of release.

v.17.08 (this release)
Technical Notes

Additional technical topics can be found on the Fotoxx web site.

Fotoxx Limitations
image files
Fotoxx has been tested with 500K image files and the performace was good. See Benchmarks below.
image size The max. supported image width or height is 20,000 pixels (compile time constant).
The maximum image size is 4 GB (about 240 megapixels).
Images edited in memory have 4 float numbers (16 bytes) per pixel (RGB + alpha).
image edits 99 edits for undo/redo and file version numbering (filename.v01 to filename.v99).
image tags
10,000 tags, 200,000 chars. for all tags, 1000 chars. for one image (compile time constants).
Thumbnail images are cached in main memory to improve gallery performance. Gallery scrolling is slower for the initial pass, and faster thereafter. Revisited galleries are fast unless the cached thumbnails have been replaced.
Running out of memory
Fotoxx can require a huge amount of main memory to edit a large image. A 20 megapixel image requires 640 megabytes for the simplest edits, and more for complex edits. Images in memory are not compressed and each RGB pixel is represented by three floating-point numbers and a transparency value (16 bytes total). HDR, Panorama and other composite functions hold all images in memory during alignment and post-process tuning. If you push the memory limits on a small PC, the Linux kernel may kill the Fotoxx process without warning and with no message (this is to keep the operating system itself from failing). What you see is that the Fotoxx window simply vanishes.

Running out of disk space
During a series of image edits, each edit step is saved on disk, and the before/after results can be viewed with the Undo/Redo button. These images use floating point numbers for color values and are not compressed. A 20 megapixel image makes a 320 MB file. If there are 10 edit steps in the undo/redo stack, the required disk space is 3.2 GB. If disk space runs out during an edit session, the program terminates with a message. To avoid this, be sure there is plenty of disk space wherever your /tmp/ directory resides. When you open a new image or quit Fotoxx, the disk space is recovered. If Fotoxx crashes, the space is recovered the next time Fotoxx is started or when the computer is rebooted.
Packages required for Fotoxx source build
See the README file for instructions on compiling Fotoxx from source.
 g++ GNU C++ compiler and C libraries
 libgtk3.0-dev  Gnome GTK3/GDK3/Pixbuf/etc. function libraries
 libtiff5-dev tiff library development files
 libpng12-dev png library development files
 liblcms2-dev Little CMS development files
Gnome geographic mapping functions
Note: package naming and contents vary by Linux distro (the usual chaos). The above names are valid for Debian-based distros (including Ubuntu). For other distros the names are different. Good luck.
Additional programs required or optional for Fotoxx
Fotoxx uses the following programs which are installed separately:
 xdg-utils  req.
open text or html files with user's preferred application
 exiftool  req.
(v. 8.60 or later) read and write image metadata (tags, comments, etc.) 
 Raw Therapee
open a RAW file for editing using its native GUI
 growisofs  opt. burn a CD or DVD with selected images
 xgamma  opt.
used for the Monitor Gamma function (adjust monitor gamma)
set of geographic maps to show image locations and report images by mouse click
 opt. PT Panorama function uses Panorama Tools (normally packaged with Hugin)
 ffmpeg, totem
required for inline viewing of video files
zappcrash - backtrace dump after a fatal error
If Fotoxx has a fatal error, it attempts to intercept the error and produce a backtrace dump which appears in a popup window. Please send this information to me so I can fix the error (contact me). A description of what you did immediately before the crash would also be helpful.
Preview Mode
Some edit functions use a reduced image size for a faster interactive response time. This is shown on the top panel as "(reduced)". When [done] is pressed, the full-size image is then processed. This is why [done] sometimes takes noticeable time. A monitor-size image (2-4 megapixels) is much faster to process than a 15-40 megapixel image (camera file). This method is used whenever the preview edits can be applied to the full-size image without visible impact (e.g. Trim/Rotate, Warp functions, brightness and color related functions). It cannot be used for some functions (e.g. sharpen, tone mapping) because the results for a small image cannot be converted for a larger image.
File Size
The file size shown on the top panel while an image is being edited is the original (unedited) file size. The file size for an edited image is not known until the image is saved on disk. In memory the size is (pixels x 16). A 20 megapixel image uses 320 megabytes in memory and typically < 4 megabytes on disk (high quality JPEG). When the edited image is saved, the correct file size is updated on the top panel.
Custom Icons
Fotoxx icons are contained in /usr/share/fotoxx/icons. You can change these if wanted.
File Types Supported
Fotoxx uses libraries to support reading and writing of image files: the GDK pixbuf library, libpng and libtiff. The file types that can be read and written include JPG/JPEG, PNG, and TIF/TIFF. Three RGB colors with 8 bits per color are supported for all types. PNG and TIFF also support 16 bits per color. Fewer than 8 bits per color and grayscale images are partly supported, and are converted to RGB internally.

Index Files
These can be found in the directory /home/<user>/.fotoxx/image_index/
The file "indexB" contains image file pathnames and metadata items that are indexed for fast searching (dates, ratings, tags, caption, comments, geotags). The file "top_directories" contains a list of the top image directories. These are searched for new image files whenever Fotoxx starts up. The last entry is the thumbnails directory.

Color Depth
8-bit color (256 brightness levels), as supported by JPEG files, is the norm for image files and is generally adequate. A difference of one brightness step (0.4% of the entire range) cannot be seen. A greater color depth than 8 bits can be useful if some part of the brightness range within an image has been greatly expanded using retouch or repair functions. This expansion can lead to visible "banding" or "posterization". If the RAW image is edited instead of the JPEG (and if the RAW image really has more than 8 bits of low-noise color), this problem can be reduced, even if the edited image is converted back to JPEG for final storage. Only the most expensive cameras with large sensors produce RAW files with more than 8 bits of low-noise color at normal light levels (status 2016).

The image below changes gradually from black to white. The color depth is 6 bits and the number of brightness levels is 64. Note that the brightness steps are barely visible.
Denoise Function - Noise Measurement
An area of radius 10 pixels around the clicked position is sampled. The RGB brightness levels reported (0-255) are the averages for this area. Within this area, every pixel is measured and compared with the mean of the surrounding 5x5 block of pixels. The RGB noise levels reported are the average differences. If the sampled area has a small gradient in brightness, the measurement is not sensitive to this. This is because the central pixel in a 5x5 block will naturally have the average RGB values of the surrounding pixels (if noise is zero). If a RAW image is measured, a 16-bit TIFF image made from the RAW is used, preserving up to 16 bits of color data if this much is available from the RAW image.
You may be surprised at the typically high noise levels in RAW images. Cameras filter out this noise when making a JPEG image. Expensive cameras with large sensors may still have RAW noise levels > 1 on the scale 0-255 (i.e. noise in bits 7-8), and even for normal ISO values around 100.

Alignment Algorithm (HDR, HDF, Stack, Panorama)
Relatively few high-contrast or "edge" pixels are selected to control alignment. The actual pixels used are shown in red during the alignment process, which is also more entertaining. Each image in succession is systematically warped various small amounts and the fit with other images is tested. This is done because two photos made with slightly different horizons or rotations will not fit perfectly with simple translation and rotation. Also camera lenses are not geometrically perfect.

Alpha Channels
Images having alpha channels (transparency information) can be edited, and the alpha channel is preserved if the image is saved as a PNG file. JPEG files do not support alpha channels.

Image Deterioration From Repeated Editing
If you save an edited image file and then use this file later to perform additional edits, pixel resolution may be lost. It is better if you do all edits when the image files are first processed, to minimize image deterioration (or go back to the originals if you still have them). Any function that changes image size or shape will reduce resolution about 1/2 pixel. These are the resize, rotate, warp, and all the composite functions. Rotating 90 degrees does not affect resolution. When downsizing an image, using the ratios 1/2, 1/3, 1/4 will give the least loss of resolution. Functions that change brightness and color do not affect resolution.
JPEG Compression
If a JPEG file from a digital camera is saved with Fotoxx, you will likely notice a large reduction in file size, even if a high JPEG quality level is used. This is because Fotoxx can afford to invest more processing power in the compression. A camera CPU is not very fast and must save an image quickly to be ready for the next photo, so the processing time available for compression is limited. The CPU of a PC is typically much faster and has more time, so the compression level is higher. The smaller file size does not mean that the quality is less.

Image Deterioration From Repeated Saving of JPEG files
Reading a compressed JPEG image and saving it again can lead to loss of detail and increased image artifacts. The effect seems to be negligible if JPEG "quality" is set to a high value when the image is saved. The image below was saved 10 times using quality=90 (Fotoxx default), each time opening and saving the previous image. Differences can be found if you look hard enough. The images are 2x size and the insets are 5x.

EXIF Errors
Cameras (esp. older ones) do not always produce structurally correct EXIF data, and the program exiftool (used by Fotoxx to manipulate EXIF data) may produce error messages. I have been able to fix these cases by saving the image file on top of itself, which will replace the EXIF data with whatever exiftool was able to read correctly. If desired data gets lost, you can restore it using the Edit Any Metadata function.

Newline characters in user Comments and Captions
When editing metadata Comments or Captions, if you need to align text in columns, you can use the [enter] key to force new lines. These are converted into the string "\n" before being stored in image EXIF/IPTC data, since newline characters are not allowed (exiftool converts them into periods). If the text is viewed or edited again, the "\n" strings are converted back to new lines, so that the original text alignments are restored. This is not standard, so don't expect the text to remain aligned if viewed in Photoshop, etc. If this is a requirement, then do not use the enter key to make new lines when entering long text - just let the text overflow to the next line by itself. In this case, column alignment is not possible.

Installed Files
Foloxx installs files in the following locations.
Repackaging by Linux distros could put them somewhere else, e.g. /opt... instead of /usr...
 /usr/bin/fotoxx the executable program file
 /usr/share/fotoxx/* user guide, translation.po files, icons, default data, etc.
 /usr/share/doc/fotoxx/* change log, man page, README and other documentation files.   

Installed Files - optional fotoxx-maps package
geographic maps data files (112 MB) 
change log, man page, README   

Local Files
Files in Fotoxx home (default /home/<user>/.fotoxx/)
These are preserved when a new release of Fotoxx is installed.
 albums/ image albums from Manage Albums function
 custom_kernel/ saved custom kernel data files
saved edit script files (for batch editing)
 favorites/ saved data for user-configuration of favorites menu
saved gallery scroll positions
 image_index/ top directories, thumbnail directory, image index file
 mashup/ saved mashup project files
saved image montage maps
saved background patterns
saved printer color calibration files
 retouch_combo/ saved settings for the Retouch Combo function
 saved_areas/ "cutout" files saved from the Select Area > Save dialog
 saved_curves/ curve data saved from Retouch curve edit dialogs
 slideshows/ user preferences from Slide Show function
saved slide show transition parameters
 thumbnails/ thumbnail files (default location, user can change this)
custom map files made by the user
 write_text/ image text overlays saved from Add Text function
 bookmarks bookmark names and image file locations
 KB-shortcuts user-defined or modified keyboard shortcuts
 logfile Fotoxx outputs that may be relevant for diagnosing problems
Batch Report Metadata output report - tabular text file
list of metadata items reported by Batch Report Metadata
metadata key names for Batch Add/Change Metadata
extra items for the metadata short report, added by the user
binary file, compressed tiles from the Mosaic function
saved locations in net map view
 pagesetup saves page setup data for print function
 parameters setup parameters that are saved across Fotoxx sessions
 plugins saves the plugins menu contents
 printsettings saves print settings data for print function
 recent_files a list of the last 100 files opened by Fotoxx, saved when Fotoxx exits
 search_results list of the last image files found with Search Images
data saved from the Fix Stuck Pixels function
 tags_defined a list of all categories and tags currently used in all images
if Fotoxx crashes, a traceback dump is deposited here
 zdialog_inputs saved dialog data for dialogs that recall prior inputs
 zdialog_positions saved dialog window positions (relative to main window)
Metadata used by Fotoxx
The following metadata items (stored inside the image files) are used by Fotoxx. These items (and any other metadata) can be viewed or edited using Fotoxx or other programs. Images can be searched using these items (or any other metadata) as selection criteria. Those marked "indexed" can be searched very fast, others more slowly (see benchmarks below). Items not listed here are searchable but not indexed.
 Metadata section and name  Usage  Indexed
 IPTC  Keywords  tags entered by user   yes
 IPTC  Rating  "star" rating entered by user   yes
 EXIF  ImageSize  pixel width and height, 1234x2345
 EXIF  DateTimeOriginal  date/time photo was made, or entered by user   yes
 EXIF  ImageHistory  history of edits made by Fotoxx
 EXIF  UserComment  comment text entered by user   yes
 IPTC  Caption-Abstract  caption or abstract text entered by user   yes
 EXIF  FocalLengthIn35mmFormat  camera focal length used, 35mm equivalent   no
 EXIF  City, Country  city/location and country from camera GPS, or entered by user   yes
 EXIF  GPSLatitude, GPSLongitude  earth coordinates from camera GPS, or entered by user   yes
 EXIF  RollAngle
 camera tilt angle - can be used to auto-level an image
Dialog Window Positioning
For commonly used dialogs, Fotoxx saves the dialog window position (relative to the main window) and tries to restore the same position the next time the dialog is started. This works, mostly. Sometimes the window manager ignores this request and places the dialog somewhere else.
Fotoxx Benchmarks
Fotoxx 17.10, Intel Core i5 3.5 GHz, large JPEG files (average 19.9 megapixels and 4.4 megabytes)
Image Index Speed (find new image files, update image index and thumbnails)
 Image index speed using a 5400 rpm disk
 Image index speed using a solid-state disk (SSD)
Image Search Speed (find image files based on metadata select criteria)
 search for indexed metadata (see list above)
 search for non-indexed metadata using a 5400 rpm disk
 search for non-indexed metadata using a solid-state disk (SSD)
Startup time by Image Index Level (Tools > User Settings)
(measured with 257K old image files and zero new image files)
Disk Type
initial startup
after reboot
5400 rpm
 25 sec.
 4.8 sec.
5400 rpm
5400 rpm
(*) Index level:
   0 = indexing disabled (search functions do not work)
   1 = use current index without updates for new image files
   2 = full indexing, including find and index new image files
Fotoxx Source Code
The C++ source code is heavily commented in the hope that others can understand and use the code for their own projects. If you have a technical question about how something works, or a better idea to pass along, you may contact me.
Questions, Problems, Bugs
If you have a question or a problem, you may contact me. If you send me any images that work poorly, I can use these to try to improve Fotoxx. If there is a traceback dump (zappcrash window), please send this to me. Please explain how to produce the error, if you can.
Technical Reference Book
I used the book "Introduction to Image Processing and Analysis" by Russ and Russ, CRC Press. It is clear and concise. The following functions were adapted from this book: flatten brightness distribution, noise reduction (median smoothing, top hat), sharpen (unsharp mask, kuwahara method), embossing, RGB/HSL conversion.
These program libraries and utilities are used within Fotoxx: GTK, libtiff, libpng, liblcms, libraw, libchamplain, exiftool, and many other libraries and tools included in Gnu/Linux. Many individuals have contributed ideas for development, time for testing, and bug reports. Translation credits are in Help > About.

Index of All Fotoxx Menu Functions
Add Lines/Arrows to Image add lines or arrows, position with mouse, set thickness, color, other styles
Add Text to Image add text, position with mouse, set font, color, transparency, other styles
Add Transparency convert a color or brightness level into transparency level
Adjust HSL replace a color tone with another, based on HSL color model
Adjust RGB/CMY adjust color levels based on RGB color model
Alien Colors
repaint an image or area with random strange colors
All Directories
show all image directories at all levels, click any for gallery view
Anti-Alias remove pixelated edges from low-resolution images
Area Copy and Paste select image area, copy and paste across images, load and save to file
Area Enable/Disable toggle between area editing and whole image editing
Area Invert exchange inside area <--> outside area
Area Open and Save save area to a file, open and re-use (paste into an image)
Area Show/Hide show or hide area outline during image editing
Area Unselect permanently remove a selected area
Batch Add/Change Metadata add or revise metadata items for selected images
Batch Add/Remove Tags add or remove multiple tags (keywords) for selected images
Batch Convert Files convert size, file type, name, location ... for selected images
Batch Delete/Trash delete or trash selected images
Batch Geotags add or revise location name and coordinates for selected images
Batch RAW process selected RAW images, save as editable files in 8 or 16 bit color
Batch Raw Therapee same as above, using the Raw Therapee image converter
Batch Rename Tags rename multiple tags (keywords) for selected images
Batch Report Metadata output metadata text file for selected metadata items and images
Batch Upright find rotated images and upright them
Blend Image
blend image pixels in areas painted with the mouse
Blur Background (Bokeh) select image areas to remain sharp and blur the rest
Blur Image blur an entire image or selected area
Bookmarks add bookmarks to image collection, go to bookmarked location
Brightness Distribution Graph show a brightness histogram, for all colors or each RGB color
Brightness Gradient add a brightness/color gradient to an image (fix uneven lighting or color)
Burn Images to DVD/BlueRay burn selected image files to DVD or Blue Ray disc
Cartoon convert an image into a cartoon
Change Language change the user interface language
Choose Map choose a local map file (world, continent, country, city)
Clone Image
use the mouse to copy from one image area to another
Color Depth set color depth from 1 to 16 bits per RGB color
Color Drawing convert an image into a simulated color drawing
Color Mode change between black/white and color, positive or negative
Color Profile change color profile (e.g. sRGB <--> Adobe RGB)
Color Saturation adjust the color saturation of an image
Copy/Move Image File copy or move an image file to another location
Copy to Desktop copy an image file to the desktop
Dark/Bright Pixels highlight pixels outside a selected brightness range
Delete Metadata delete selected metadata items or all metadata
Delete/Trash Image File delete an image file or move it to the trash bin
Denoise Image reduce noise in a photo made under low light conditions
Directed Blur blur the image in one direction (perpendicular direction remains sharp)
Dots convert an image into a dot matrix (Roy Lichtenstein effect)
Edit Any Metadata edit any metadata item
Edit Brightness Distribution edit the brightness distribution directly (shift pixel brightness levels)
Edit Metadata edit main metadata items (date/time, tags, rating, location, caption)
Embossing add a 3D relief effect to an image
Export File List export a text file list of selected images (for external program feed)
Export Image Files
export (copy) selected image files to a directory (for web upload ...)
Favorites graphic popup menu with user-selected functions, icons, and layout
Find Area Gap show where there is a gap in a Select Area hand-drawn outline
Find Duplicate Images find duplicate images within the entire image collection
Fix Perspective correct the perspective of a photo made at an angle
Flatten Book Page flatten a photo of a curvy page from a thick book
Flip Image invert an image left-right or top-bottom
Graduated Blur preserve high-contrast pixels and blur the rest, scaled by contrast
Grid Lines set grid lines on or off, or change horizontal and vertical counts
High Depth of Field (HDF) combine near- and far-focus photos for extended focus depth
High Dynamic Range (HDR) combine low- and high-brightness photos for extended brightness range
Image Locations Report list image locations and date groups, click on list for gallery of images
Images by Map Location click on a map marker for a gallery of images at that location
Image Timeline Report list image counts by year and month, click on list for gallery of images
Index Image Files installation utility - find all image files and make an index for fast searching
Keyboard Shortcuts show keyboard shortcuts and define custom shortcuts
Leverage Edits regulate the intensity of an edit function using brightness, contrast, or color
Line Color change the color used for image lines (area outlines, mouse "paintbrush")
Local Color adjust colors in multiple image areas with adjustable blending
Make Waves image wave warp, vary intensity, wavelength, randomness
Manage Albums create and arrange arbitrary ordered views of images without duplications
Manage Tags create tags (keywords) and categories, for managed image tagging
Mashup photomontage - combine images and text in an arbitrary layout
Match Colors match colors in one image to the colors in another image
Missing Translations list the missing translations for a given language
Monitor Color show a color pattern on the monitor for adjusting brightness and contrast
Monitor Gamma show a special image on the monitor for adjusting gamma
Montage join many images together in a compact rectangular format
Mosaic convert an image into a mosaic of image tiles which can be clicked to view
Net Map world map at any scale, retrieved as needed from the internet
Net Map Locations save and recall map locations (center and zoom level)
Net Map Source select optional source (web site) for internet map
New Blank Image create a blank image with a desired color (background for later use)
Newest Images show the newest images based on photo date or file date
New Window create a parallel Fotoxx window
Open Image File standard file open dialog to select an image file to view or edit
Open Previous File show the previous file - instant toggle between any two files
Open RAW File open a RAW file to view or edit (tiff file with 16 bits per RGB color)
Organizing for Searching how image organization, naming, and metadata affects search capability
Paint Image
paint a color over an image area with the mouse
Paint Edits "paint" an edit function locally and gradually with the mouse
Paint Transparency "paint" image transparency locally and gradually with the mouse
Panorama Image combine 2-4 images into a wide panorama with automatic edge fitting
Pattern tile the image with a repeating pattern, vary contrast and transparency
Pencil Sketch convert an image into a simulated pencil sketch
Plugins add a menu for an external plugin function, or call the function
Previous/Next Image go to the previous or next image in the current gallery
Print Calibrated Image print an image using a predefined printer color profile
Printer Color Calibration compute a calibrated color profile for a printer
Print Image File print an image with custom margins and scaling
PT Panorama combine images into a panorama using the Panorama Tools program
Recent Images show the most recent images viewed or edited
Red Eyes remove red eyes from photos made with flash lighting
Remove Dust remove dust spots from scanned slides or archaic images
Rename Image File file rename function, easy to use for a series of images
Replace Album File substitute one file for another in selected or all albums
Resize Image change the image scale with presets for 3/4, 2/3, 1/2, 1/3, 1/4
Resources report memory usage to log file (leak detector)
Retouch Combo edit brightness, contrast, color, color temperature, white balance ...
Save to Disk save modified image to same file, to new version or to new file
Script Files record a series of edits with one file, then execute on many files
Search Images Report find images based on date, rating, tags, caption text, location/file name ...
Select Area select image area(s) to be edited separately from background
Select Hairy special tool to select a ragged or hairy area with speed and precision
Selective Rescale shrink an image while leaving a selected area unchanged
Set Map Markers
set the map markers to show all images or only the current gallery
Sharpen Image sharpen fuzzy edges within an image
Shift Colors shift image RGB colors with a sliding scale: GBR <-- RGB --> BRG
Show Captions toggle display of captions and comments in upper left image corner
Show RGB show RGB values at selected image locations, also during edits
Slide Show show album images in sequence with animated transitions and pan/zoom
Smart Erase replace power lines, signs, ground litter, etc. with neighborhood pixels
Spherical Projection project an image into a sphere, variable size and flatness
Stack/Noise combine multiple high ISO noisy photos to make one with reduced noise
Stack/Paint combine photos taken at different moments to eliminate transient objects
Stuck Pixels find and map stuck pixels, use map to heal photos from the same camera
Sync Gallery set the gallery to the directory of the current image file
Texture add texture to an image by amplification of existing brightness variation
Tiles convert an image into tiles with variable 3D effect
Tone Mapping amplify low contrast details without changing overall contrast
Trim (crop) and Rotate
combination function to level a tilted image and trim margins
Twist Image
twist an image around a chosen center point
Unbend Images fix perspective for a curved wide-angle image, especially panoramas
Undo/Redo Button step forward or backward through image edit stages, or go to any stage
Uninstall Appimage
completely remove an AppImage package
Unwarp Closeup remove distortion from close-up face photos (balloon face, big nose)
Update Albums auto update albums to latest file versions
Upright Image rotate image -90 or +90 degrees (automatic if EXIF orientation available)
User Settings dialog for user settable options
Vertical Panorama combine 2-4 images into a vertical panorama with automatic edge fitting
Video Files
play video files contained in the Fotoxx image collection
Vignette fix camera vignette (dark corners) or design a vignette with any shape
View Metadata brief report of most significant metadata, or full report of everything
Voodo 1 and Voodo 2 automatic image enhancement (1-click) that often works well enough
Warp Affine warp image with affine transformation (parallel lines remain parallel)
Warp Area warp within a Select Area by dragging the image with the mouse
Warp Curved warp image by mouse dragging, with range from 1-100% of image size
Warp Linear warp image by dragging one corner - straight lines remain straight
Web Service Photo Upload
how to batch upload image files to an online photo service
World Map select from locally stored map files: world, continents, countries
Zonal Flatten bring details out of shadows and other low-contrast areas