Installation
To install Fotoxx, try the appropriate package first: packages. It may install OK with one click. If not, you must install from source code. Instructions are here: downloads. Fotoxx should show up in the system menu after installation (or maybe after a new login). If not, use the command "fotoxx" in a terminal window or launcher.
Initialization
Fotoxx needs to know where all your image files are located (directory and file names) and their imbedded metadata (if any): tags, geotags, captions, comments, ratings and dates. This data is indexed for fast searching. Fotoxx also creates thumbnail images on disk, so that the gallery windows (thumbnail pages) will work fast. Fotoxx does not modify or copy the image files - it only reads them to get data for the search index and to make thumbnails. After completion, the gallery windows and search functions will work very fast.
When Fotoxx starts, it checks for a top image directory and search index. These will be missing the first time Fotoxx is started, and a popup dialog will ask you to supply a few key items of information:
The
top image directory is simply a directory containing all your image
files (or subdirectories with image files). This is typically named
"/home/<user>/Photos" or similar. Use the [browse] button to
locate this directory. You may also specify multiple top image
directories if needed. Other files may be mixed with your image files. The file sync function should normally be enabled. If it is not, you can still use Fotoxx to view and edit image files, but the metadata functions will not work and will be disabled until a file sync is done (these include adding tags, geotags, comments, etc. and all image search functions). You can do the file sync manually at a later time if desired (see Synchronize Files).
For thumbnail files, you have three options: (1) None: do not create thumbnail files (the gallery windows will be slow). (2) Thumbnail files are placed in a hidden directory (.thumbnails) in the same directory as the corresponding image files. (3) Use a dedicated directory where thumbnail files are kept. This must be outside the top directories containing the image files (suggestion: /home/<user>/.fotoxx/thumbnails).
If you have many thousands of images, the file sync function may need significant time. A strong computer will process 1500+ images per minute. Some computers will be much slower. When you start Fotoxx after new image files have been added to your collection, the synchronize function starts automatically to process the new images. This normally needs a few seconds unless there are hundreds of new images. For more details, see Synchronize Files.
Test Run
After Fotoxx finishes initialization, use the [open] button on the toolbar to select an image file to view in window tab F (face icon). Choose the menu Retouch > Brightness/Color, and in the dialog use the [+++] button to brighten the image. Use the [cancel] button to leave the dialog without changing the image file on disk. Use the tab G button (gallery icon) to see all the images in the current directory. Use the navigation buttons on the gallery window to navigate within the directory. Click on a thumbnail image to view the image in tab F. If this all works then Fotoxx is installed OK.
Essential Information for those who hate big user manuals (you and me):
o Menu functions and dialogs have live help activated by keyboard F1.
o Zoom an image in/out with left/right mouse click or mouse wheel.
o Pan and scroll a zoomed image with mouse left-drag (invisible scroll bars).
o Tab G: view a thumbnail gallery of images in the current directory.
o Click a thumbnail: show big image in tab F. Use menus to edit image.
o The window title bar has the current image file and directory names.
o The status bar at the bottom has image and edit status information.
This User Guide is available in the menu Help > User Guide. The F1 key will bring up a help topic for the current menu or dialog. This appears in your chosen web browser (and can get hidden under the Fotoxx window if you use maximized windows).
Navigation - Tabs F and G
Use window Tab G to show an image gallery window (thumbnails) showing image files in the current directory. Use this window to scroll around and select image files by clicking thumbnails. The arrow buttons allow scrolling forward or back by rows or pages. Use the zoom buttons to change the thumbnail size and the number of thumbnails fitting in the window. Clicking on a thumbnail will show the full-size image in Tab F. Pressing Tab G will show the gallery, with the current image in Tab F scrolled to the top row. The current directory path is shown at the top of the gallery window. Click on one of the higher level directories to go to that directory. Its subdirectories will be shown as folders. Click on 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 the Fotoxx database.
There are several types of gallery windows:
)
This function can help 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
toolbar [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. If you are using sequence numbers, press
the [add 1] button to increment the sequence number. 
This function is
used to view or change custom keyboard shortcuts. The currently
assigned shortcuts are shown in the window. To change one of these,
click on it to make the key assignment and menu name appear below (the
example shows shortcut keys Alt+G for the function Grid Lines). 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. When done, press [apply] to update the
list. To add a new shortcut, select a menu function from the drop-down
list (lower right), enter a shortcut using the keyboard, and then press
[apply] to update the list. To remove a shortcut, select it and press [Delete]. When you are finished making shortcuts,
press [save] to make the changes permanent (a file is updated). If you
press [cancel] or [x] all changes will be discarded. The shortcuts
shown in the previous tables
are reserved and changing them is blocked.
This
function is helpful if you want many image files (perhaps with the same
date or from the same event) to have the same names with an added
sequence number. In the dialog, specify a base name, a starting
sequence number, and an increment. In the base name, specify where you
want the sequence number with '#' characters. For example, a base name
of "arctic cruise ###-2012", a starting sequence number of 100, and an
increment of 10 will produce a series of file names like this: 
Gamma determines
how RGB brightness values (0-255) are converted into brightness as
perceived by the eye. The standard value is 2.2 and this should
normally be used for image editing. An adjustment chart is provided,
courtesy of Norman Koren.
Adjust the dialog slider until the middle band has the same brightness
as the upper and lower bands at scale location 2.2. The chart only
works at 100% size, so 
The
dialog displays the location data for the current image, if any. The
live display is updated when a new image is opened. For an image with
missing or incorrect location data, enter a city name and use the
[Find] button to either complete the data in the dialog, or get a list
of matching cities to choose from (e.g. Bermingham, United Kingdom and
Bermingham, United States). 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 search index for later searching by location.
If the data is revised in the dialog (spelling of city/country, or
revision of latitude/longitude), this will take precedence for future
city searches. Use the [Prev] button to fill the dialog data with the
last location used. If the [Find] button does not find a city (it is
missing from the cities-geotags file), you can use the [Web] button to
find the city and location data from an internet web service (MapQuest
Open for now, but this can change). The location data is completed and
returned into the dialog. These names are not standardized and there
are many duplicates, 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 it will be available from
now on for other images by using the [Find] button. If the [Web] button
fails, you can manually find the city in the internet and enter the
location data into the Edit Geotags dialog. Pressing [apply] will add
the data to the current image and make the location available for
future use. 
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 Geotags. Press
[proceed] to start the update process. Use this function also to
correct city/country spellings or latitude/longitude data, or to fix
inconsistencies. 
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 edits.
The [Hide] button removes the area outline, giving you better
visibility of image edits and 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.
This function sets a new image
width and height. You can input the new pixel width and height directly
or choose a percent change for width and height. Buttons are present
for setting the new size to 3/4, 2/3, 1/2, 1/3, or 1/4 of the original
size. Using one of these ratios will minimize loss of resolution. If
the lock ratio box is checked, the original width / height ratio will
be preserved, meaning that if one dimension is changed, the other
dimension will be changed to match. The change is made immediately, but
the image will look the same unless it becomes smaller than the window,
causing a visible shrinkage. Leave the dialog with [done] to save the
changes or [cancel] to keep the original size. The image file size
(status bar) is not updated until the modified image is saved.
With
this function you can
write 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. The [apply]
button makes the
current text 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 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. 
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. HDR images often seem
"flat" because the contrast between nearby pixels has been reduced to
make the overall contrast fit within the available range. 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:
adjusting the brightness curve can increase contrast for a selected
brightness range (possibly at the expense of others). Flattening the
brightness distribution can spread the available contrast (brightness
range) more evenly. Increasing color saturation can also bring out more
detail. These methods operate globally: all pixels of a given color and
brightness are processed the same. Tone mapping processes pixels
differently depending on the brightness of surrounding pixels and is
more effective at enhancing detail and the perceived brightness range. 
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. This function redistributes the
pixel brightness so that each brightness level is more equally
represented. Technically, the brightness distribution is made more
uniform (flatter). 
This
function expands the brightness range of an image that does not utilize
the full brightness range available, possibly making it look
contrast-poor. You can see this in the brightness distribution graph.
If the distribution shows little or no area at the extreme low and high
ends of the horizontal scale, the image may benefit from expanding the
brightness range. This means that the darkest pixels are made darker
and/or the brightest pixels are made brighter. Move the sliders to
extend the brightness range and observe the image. 
This
function varies the brightness across an image, with the direction and
magnitude of the brightness slope determined by editable curves. You
can use this to compensate for uneven lighting or vignetting (darker
image corners). The function dialog displays two editable curves,
horizontal and vertical. The horizontal curve adjusts brightness
horizontally, and the vertical curve adjusts brightness vertically.
Move the curves in the directions labeled "+" and "‒" to increase or
decrease the image brightness in the corresponding image area. To
remove vignetting in the image corners, move both ends of both curves
in the "+" direction while fixing the middle areas or even moving them
in the "‒" direction. To brighten the upper right corner, move the
right end of the horizontal curve and the upper end of the vertical
curve in the "+" direction, as in the example above. 
Use
this function in combination with some other retouch edit function.
Specify a mouse radius and "power" factors for the mouse center and
radius edge. Then start a retouch edit function if not already active.
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 Brightness/Color, and the brightness curve is set to a
high level, then the image will be slowly brightened in the area where
the mouse is dragged. 
It
is sometimes effective to apply a retouching 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 the menu
Select > Leverage Edits. Choose brightness or contrast as the
controlling attribute (lever). The lever may be for a single RGB color
or for all colors. The editable graph controls how subsequent edit
functions are applied to the image. The x-axis is the selected lever
(brightness or contrast), from minimum to maximum value. The y-axis
value governs how strongly an edit function affects a pixel having the
attribute value on the x-axis. A low y-value minimizes the effect, and
a high y-value maximizes it. 
This
function sharpens a blurry image. Three methods are implemented: edge
detection, unsharp mask, and gradient. Edge detection: find adjacent
pixels with the largest brightness difference (contrast) and increase
the difference. This is repeated for several cycles, with the threshold
for brightness difference decreased each cycle. Unsharp mask: a fast
and effective method also found in Gimp and other tools. A technical
description can be found via Google. Gradient: pixels are processed
left to right and top to bottom. The brightness difference (contrast)
between each pixel and its prior neighbors (left and above) is
increased, and the pixel brightness is modified to match. This
brightness change is propagated to the next pixel where the process is
repeated. 
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 (e.g. <20 pixels wide). 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 toolbar 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.
Images
made from dusty scanned slides can have many small dark spots - shadows
of the dust on the slides. 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. 
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. 
This
function is an easy way to remove a false color-cast, e.g. the whole
image has an overall blue or red tinge. After starting the function,
click somewhere on the image that should have no color - a white or
gray area. If that location has any color other than white or gray, it
will be used as a measure of overall false color, and this amount of
color will be removed from the whole image. You can click around on
various areas and see the impact instantly. The "warmer" slider can be
used to directly change the color temperature. This is especially
useful if there are no convenient gray/white areas. The "reduce" slider
can be
used to reduce the amount of change from 100% to zero.
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 is
taken from another image. 
This function is used to change
overall brightness or selected colors using OD (optical density) units.
The input values range from -99 to +99 which represent -0.99 to +0.99
OD. OD is a logarithmic scale where -1 is a 10x increase and +1
is a 10x decrease in brightness. The input steps (0.01 OD) make a 2.3%
change in brightness, which is barely visible with undo/redo and not
visible with a side-by-side comparison. The contrast buttons change
contrast by 0.01 OD per step, meaning that the brightest and darkest
pixels are changed by 0.01 OD in opposite directions, with intermediate
pixels changed proportionally.
Panoramas of nearby subjects
(typically buildings or interior rooms) may show straight lines that
are curved, or buildings that are slanted. Bending of the images is
necessary in the panorama process in order for the images to fit
together. For remote subjects (esp. landscapes) this is not noticeable.
The unbend function can be used to straighten curved lines and remove
the slant from vertical lines. 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. Input values for horizontal and
vertical unbend and watch the effect on the image. Increase or decrease
the values and repeat until satisfied. Move the axes to change the
centers of unbending. The linear values will slant the image left/right
or top/bottom edges to remove slant. The curved values will straighten
the image curving that comes from making a panorama. See also "Warp
Image" for another method of correcting image curving and perspective
problems.
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. 
This
function converts 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,
reaching 100% replacement at the slider end positions. For example, you
can gradually substitute green or blue for the color red.
There are
two functions in this dialog. 
Select
the HDR menu function. A file open dialog is started to select up to 9
image files, which must all have nearly the same pixel dimensions. The
images are aligned and combined automatically, which may need a minute
or more. When done, the combined image is shown, along with a dialog
for manual adjustments. The contributions from the input images are
shown as a series of editable curves. The horizontal scale represents
pixel brightness, from dark to bright white. 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 anchor points (small squares on a curve) can be pulled
around while others remain fixed. The corresponding image contributions
are changed accordingly, and you can see the results in quasi-real-time
in the output image. Right-click on an anchor point to remove it. 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: Flatten, Expand Brightness,
Brightness/Color, 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. 
Combine
(overlay) multiple photos of the same subject taken at different times.
Remove tourists and cars that come and go between shots by painting
them away with the mouse. 
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. 
Using the panorama menu function, select 2-4 image files. The images
are initially joined and shown with a small transparent overlap. A
pre-align dialog 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 its 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. The lens bow parameter
(barrel or pincushion distortion) is not available in EXIF and must be
adjusted manually, but this is often insignificant and can be left at
zero. You can measure and set the lens parameters manually as described
below. 
When fine alignment is complete,
the combined image is displayed. A dialog pops up 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. The other controls allow
you to make additional changes to better match the images. Select one
of the images with the radio buttons at the top, 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. 