neulab/tldr huggingface dataset:
This version of jpegtran also offers a lossless crop option, which discards data outside of a given image region but losslessly preserves what is inside.  Like the rotate and flip transforms, lossless crop is restricted by the current JPEG format; the upper left corner of the selected region must fall on an iMCU boundary.  If it doesn't, then it is silently moved up and/or left to the nearest iMCU boundary (the lower right corner is unchanged.)  Thus, the output image covers at least the requested region, but it may cover more.  The adjustment of the region dimensions may be optionally disabled by attaching an
The image can be losslessly cropped by giving the switch:
-crop WxH+X+Y Crop the image to a rectangular region of width W and height H, starting at point X,Y.  The lossless crop feature discards data outside of a given image region but losslessly preserves what is inside.  Like the rotate and flip transforms, lossless crop is restricted by the current JPEG format; the upper left corner of the selected region must fall on an iMCU boundary.  If it doesn't, then it is silently moved up and/or left to the nearest iMCU boundary (the lower right corner is unchanged.)
If W or H is larger than the width/height of the input image, then the output image is expanded in size, and the expanded region is filled in with zeros (neutral gray).  Attaching an 'f' character ("flatten") to the width number will cause each block in the expanded region to be filled in with the DC coefficient of the nearest block in the input image rather than grayed out.  Attaching an 'r' character ("reflect") to the width number will cause the expanded region to be filled in with repeated reflections of the input image rather than grayed out.
A complementary lossless wipe option is provided to discard (gray out) data inside a given image region while losslessly preserving what is outside:
-wipe WxH+X+Y Wipe (gray out) a rectangular region of width W and height H from the input image, starting at point X,Y.
Attaching an 'f' character ("flatten") to the width number will cause the region to be filled with the average of adjacent blocks rather than grayed out.  If the wipe region and the region outside the wipe region, when adjusted to the nearest iMCU boundary, form two horizontally adjacent rectangles, then attaching an 'r' character ("reflect") to the width number will cause the wipe region to be filled with repeated reflections of the outside region rather than grayed out.
A lossless drop option is also provided, which allows another JPEG image to be inserted ("dropped") into the input image data at a given position, replacing the existing image data at that position:
-drop +X+Y filename Drop (insert) another image at point X,Y
Both the input image and the drop image must have the same subsampling level.  It is best if they also have the same quantization (quality.) Otherwise, the quantization of the output image will be adapted to accommodate the higher of the input image quality and the drop image quality.  The trim option can be used with the drop option to requantize the drop image to match the input image.  Note that a grayscale image can be dropped into a full-color image or vice versa, as long as the full- color image has no vertical subsampling.  If the input image is grayscale and the drop image is full-color, then the chrominance channels from the drop image will be discarded.
Other not-strictly-lossless transformation switches are:
-grayscale Force grayscale output.
This option discards the chrominance channels if the input image is YCbCr (ie, a standard color JPEG), resulting in a grayscale JPEG file.  The luminance channel is preserved exactly, so this is a better method of reducing to grayscale than decompression, conversion, and recompression.  This switch is particularly handy for fixing a monochrome picture that was mistakenly encoded as a color JPEG.  (In such a case, the space savings from getting rid of the near-empty chroma channels won't be large; but the decoding time for a grayscale JPEG is substantially less than that for a color JPEG.)
jpegtran also recognizes these switches that control what to do with "extra" markers, such as comment blocks:
-copy none Copy no extra markers from source file.  This setting suppresses all comments and other metadata in the source file.
-copy comments Copy only comment markers.  This setting copies comments from the source file but discards any other metadata.
-copy icc Copy only ICC profile markers.  This setting copies the ICC profile from the source file but discards any other metadata.
-copy all Copy all extra markers.  This setting preserves miscellaneous markers found in the source file, such as JFIF thumbnails, Exif data, and Photoshop settings.  In some files, these extra markers can be sizable.  Note that this option will copy thumbnails as-is; they will not be transformed.
The default behavior is -copy comments.  (Note: in IJG releases v6 and v6a, jpegtran always did the equivalent of -copy none.)
Additional switches recognized by jpegtran are:
-icc file Embed ICC color management profile contained in the specified file.  Note that this will cause jpegtran to ignore any APP2 markers in the input file, even if -copy all or -copy icc is specified.
-maxmemory N Set limit for amount of memory to use in processing large images. Value is in thousands of bytes, or millions of bytes if "M" is attached to the number.  For example, -max 4m selects 4000000 bytes.  If more space is needed, an error will occur.
-maxscans N Abort if the input image contains more than N scans.  This feature demonstrates a method by which applications can guard against denial-of-service attacks instigated by specially-crafted malformed JPEG images containing numerous scans with missing image data or image data consisting only of "EOB runs" (a feature of progressive JPEG images that allows potentially hundreds of thousands of adjoining zero-value pixels to be represented using only a few bytes.)  Attempting to transform such malformed JPEG images can cause excessive CPU activity, since the decompressor must fully process each scan (even if the scan is corrupt) before it can proceed to the next scan.
-outfile name Send output image to the named file, not to standard output.
-report Report transformation progress.
-strict Treat all warnings as fatal.  This feature also demonstrates a method by which applications can guard against attacks instigated by specially-crafted malformed JPEG images.  Enabling this option will cause the decompressor to abort if the input image contains incomplete or corrupt image data.
-verbose Enable debug printout.  More -v's give more output.  Also, version information is printed at startup.
-debug Same as -verbose.
-version Print version information and exit.
This example converts a baseline JPEG file to progressive form:
jpegtran -progressive foo.jpg > fooprog.jpg
This example rotates an image 90 degrees clockwise, discarding any unrotatable edge pixels:
jpegtran -rot 90 -trim foo.jpg > foo90.jpg
JPEGMEM If this environment variable is set, its value is the default memory limit.  The value is specified as described for the -maxmemory switch.  JPEGMEM overrides the default value specified when the program was compiled, and itself is overridden by an explicit -maxmemory.
cjpeg(1), djpeg(1), rdjpgcom(1), wrjpgcom(1) Wallace, Gregory K.  "The JPEG Still Picture Compression Standard", Communications of the ACM, April 1991 (vol. 34, no. 4), pp. 30-44.
Independent JPEG Group
This file was modified by The libjpeg-turbo Project to include only information relevant to libjpeg-turbo and to wordsmith certain sections.
The transform options can't transform odd-size images perfectly.  Use -trim or -perfect if you don't like the results.
The entire image is read into memory and then written out again, even in cases where this isn't really necessary.  Expect swapping on large images, especially when using the more complex transform options.
FEH(1)                     BSD General Commands Manual                    FEH(1)
feh — image viewer and cataloguer
feh [options] [--] [files | directories | URLs ...]
This manual documents feh 3.7.2
Compile-time switches in this build: •   libcurl remote file support enabled •   Xinerama multi-monitor support enabled •   libexif builtin EXIF reader available •   inotify-based auto-reload of changed files enabled
feh is a light-weight, configurable and versatile image viewer.  It is aimed at command line users, but can also be started from graphical file managers.  Apart from viewing images, it can compile text and thumbnail listings, show (un)loadable files, set X11 backgrounds, and more.
Features include filelists, various image sorting modes, custom action scripts, and image captions.  feh can be controlled by configurable keyboard and mouse shortcuts, terminal input and signals.  When no file arguments or filelists are specified and --start-at is not used, feh displays all files in the current directory.
EXIF tags are supported either using exiv2 / exifgrep via --info (see the USAGE EXAMPLES section), or as a builtin feature by compiling feh with exif=1. In this build of feh, builtin EXIF support is available.
feh is based on various modes, which are selected at startup by command line options.
Slideshow mode is the default.  It opens a window and displays the first image in it; the slideshow position can be advanced (or otherwise changed) using keyboard and mouse shortcuts.  In slideshow mode, images can be deleted either from the filelist or from the disk, a changed filelist can also be saved to the disk and reopened at a later time.  An image can also be read from stdin via "feh -".
Montage mode forms a montage from the filelist.  The resulting image can be viewed or saved, and its size can be limited by height, width or both.
Index mode forms an index print from the filelist.  Image thumbnails are shown along with the filename, size and dimensions, printed using a truetype font of your choice.  The resulting image can be viewed or saved, and its size can be limited by height, width or both.
Thumbnail mode is like index mode, but the mini-images are clickable and open the selected image in a new window.
Multiwindow mode shows images in multiple windows, instead of as a slideshow in one window.  Don't use with a large filelist ;)
List mode doesn't display images.  Instead, it outputs an ls-style listing of the files in the filelist, including image info such as size, number of pixels, type, etc.  There is also a Customlist mode which prints image info in a custom format specified by a printf-like format string.
feh can also list either all the loadable files in a filelist or all the unloadable files.  This is useful for preening a directory.
feh can open any format supported by imlib2, most notably jpeg, png, pnm, tiff, and bmp.  The gif format is also supported, but only for static images.  In case of animations, only the first frame will be shown.  If the convert binary (supplied by ImageMagick) is available, it also has limited support for many other file types, such as svg, xcf and otf.  If dcraw is available, feh also supports RAW files provided by cameras and will display the embedded thumbnails.  Use --conversion-timeout timeout with a non- negative value to enable support for these formats.
As Imlib2 may take several seconds to determine whether it can load a file or not (e.g. when attempting to open a large video), feh checks each file's header before loading it.  If it looks like an image, it is passed on to Imlib2, otherwise, it is assumed to be unloadable.  This greatly improves performance when working in directories with mixed files (i.e., directories which do not exclusively contain image files).  If you think that Imlib2 can load a file which feh has determined to be likely not an image, set the environment variable "FEH_SKIP_MAGIC" to pass all files directly to Imlib2, bypassing the header check.  The environment variable's value does not matter, it just needs to be set.
-A, --action [flag][[title]]action Specify a shell command as an action to perform on the image.  In slideshow or multiwindow mode, the action will be run when the action_0 key is pressed, in list mode, it will be run for each file.  In loadable/unloadable mode, it will be run for each loadable/unloadable file, respectively.  In thumbnail mode, clicking on an image will cause the action to run instead of opening the image.
If flag is ";", feh will reload the current image instead of switching to the next one (slideshow mode) or closing the window (multiwindow mode) after executing the action.  If [title] is specified (note the literal "[" and "]"), --draw-actions will display title instead of action in the action list.  Note that title must not start with a space.  If it does, the action is handled as if it did not have a title.  This special case exists for backwards compatibility reasons and makes sure that actions like "[ -L %F ] && foo" still work.
The action will be executed by /bin/sh.  Use format specifiers to refer to image info, see FORMAT SPECIFIERS for details.  Example usage: "feh -A "mv %F ~/images/%N" *".
--action1 .. --action9 [flag][[title]]action Extra actions which can be set and triggered using the appropriate number key.
--auto-reload (optional feature, enabled in this build) automatically reload image when the underlying file changes.  Note that auto-reload (if enabled in the build) is on by default.  This option is only useful to re-enable auto-reload after it has been disabled by a preceding --reload=0 option.
Automatic reload is not supported in montage, index, or thumbnail mode.
--auto-rotate (optional feature, available in this build) Automatically rotate images based on EXIF data.  Does not alter the image files.
-Z, --auto-zoom Zoom pictures to screen size in fullscreen / fixed geometry mode.
-x, --borderless Create borderless windows.
--cache-size size Set imlib2 in-memory cache to size MiB.  A higher cache size can significantly improve performance especially for small slide shows, however at the cost of increased memory consumption.  size must be between 0 and 2048 MiB and defaults to 4.
-P, --cache-thumbnails Enable thumbnail caching.  Thumbnails are saved in $XDG_CACHE_HOME/thumbnails, which defaults to ~/.cache/thumbnails. Note that thumbnails are only cached if the configured thumbnail size does not exceed 256x256 pixels.
-K, --caption-path path Path to directory containing image captions.  This turns on caption viewing, and if captions are found in path, which is relative to the directory of each image, they are overlayed on the displayed image.  E.g. with caption path "captions/", and viewing image "images/foo.jpg", the caption will be looked for in "images/captions/foo.jpg.txt".
--conversion-timeout timeout feh can use ImageMagick to try converting unloadable files into a supported file format.  As this can take a long time, it is disabled by default.  Set timeout to a non-negative value to enable it.  A positive value specifies after how many seconds conversion attempts should be aborted, zero causes feh to try indefinitely. Negative values restore the default by disabling conversion altogether.
--class class Set the X11 class hint to class.  Default: feh
-L, --customlist format Don't display images, print image info according to format instead. See FORMAT SPECIFIERS.
-G, --draw-actions Draw the defined actions and what they do at the top-left of the image.
--draw-exif (optional feature, available in this build) display some EXIF information in the bottom left corner, similar to using --info with exiv2 / exifgrep.
-d, --draw-filename Draw the file name at the top-left of the image.
--draw-tinted Show overlay texts (as created by --draw-filename et al) on a semi- transparent background to improve their readability.
--edit  Enable basic editing of files.  This makes rotation and mirroring (bound to "<", ">", "|", and "_" by default) change the underlying file and not just its displayed content.
-f, --filelist file This option is similar to the playlists used by music software.  If file exists, it will be read for a list of files to load, in the order they appear.  The format is a list of image file names, absolute or relative to the current directory, one file name per line.
If file doesn't exist, it will be created from the internal filelist at the end of a viewing session.  This is best used to store the results of complex sorts (-Spixels for example) for later viewing.
Any changes to the internal filelist (such as deleting a file or it being pruned for being unloadable) will be saved to file when feh exits.  You can add files to filelists by specifying them on the command line when also specifying the list.
If file is "-", feh will read the filelist from its standard input.
-e, --font font Set global font.  Should be a truetype font, resident in the current directory or the font directory, and should be defined in the form fontname/size, like "yudit/12" (which is the default).
-C, --fontpath path Specify path as extra directory in which to search for fonts; can be used multiple times to add multiple paths.
--force-aliasing Disable anti-aliasing for zooming, background setting etc.
-I, --fullindex Same as index mode, but with additional information below the thumbnails.  Works just like "feh --index --index-info "%n\n%S\n%wx%h"".  Enables MONTAGE MODE OPTIONS.
Note: This option needs to load all images to calculate the dimensions of the feh window, so when using it with many files it will take a while before a feh window is visible.  Use --preload to get a progress bar.
-F, --fullscreen Make the window fullscreen.  Note that in this mode, large images will always be scaled down to fit the screen, and --zoom zoom only affects smaller images and never scales larger than necessary to fit the screen size.  The only exception is a zoom of 100, in which case images will always be shown at 100% zoom.
When combined with --thumbnails, this option only affects images opened from the thumbnail overview.  The thumbnail list itself will still be windowed.
-g, --geometry width x height | + x + y | width x height + x + y Use a fixed window size as specified in the X-style geometry string, e.g. 640x480.  An optional +x+y window offset can be specified.  Combine with --scale-down to scale down larger images like in fullscreen mode.  Note that this option does not enforce the window size; changing it by a tiling WM or manually is still possible.  However, auto-resize remains disabled.
-Y, --hide-pointer Hide the pointer (useful for slideshows).
-B, --image-bg style Use style as background for transparent image parts and the like. Accepted values: default, checks, or an XColor (e.g. "black" or "#428bdd").  Note that some shells treat the hash symbol as a special character, so you may need to quote or escape it for the XColor code to work.  In windowed mode, the default is checks (a checkered background so transparent image parts are easy to see). In fullscreen and background setting mode, checks is not accepted and the default is black.
-i, --index Enable Index mode.  Index mode is similar to montage mode, and accepts the same options.  It creates an index print of thumbnails, printing the image name beneath each thumbnail.  Index mode enables certain other options, see INDEX AND THUMBNAIL MODE OPTIONS and MONTAGE MODE OPTIONS.
--info [flag]command_line Execute command_line and display its output in the bottom left corner of the image.  Can be used to display e.g. image dimensions or EXIF information.  Supports FORMAT SPECIFIERS.  If flag is set to ";", the output will not be displayed by default, but has to be enabled by the toggle_info key.
--insecure When viewing files with HTTPS, this option disables all certificate checks.  It allows images on sites with self-signed or expired certificates to be opened, but is no more secure than plain HTTP.
-k, --keep-http When viewing files using HTTP, feh normally deletes the local copies after viewing, or, if caching, on exit.  This option permanently stores them on disk, either in the directory specified by --output-dir, or in the current working directory.
--keep-zoom-vp When switching images, keep zoom and viewport settings (zoom level and X, Y offsets)
-l, --list Don't display images.  Analyze them and display an ls(1) - style listing.  Useful in scripts to hunt out images of a certain size/resolution/type etc.
-U, --loadable Don't display images.  Just print out their names if imlib2 can successfully load them.  Returns false if at least one image failed to load.
--max-dimension width x height Only show images with width <= width and height <= height.  If you only care about one parameter, set the other to 0 (or a negative value).
-M, --menu-font font Use font (truetype, with size, like "yudit/12") as menu font.
--min-dimension width x height Only show images with width >= width and height >= height.  If you only care about one parameter, set the other to 0.
-m, --montage Enable montage mode.  Montage mode creates a new image consisting of a grid of thumbnails of the images in the filelist.  When montage mode is selected, certain other options become available. See MONTAGE MODE OPTIONS.
-w, --multiwindow Disable slideshow mode.  With this setting, instead of opening multiple files in slideshow mode, multiple windows will be opened; one per file.
--no-conversion-cache When loading images via HTTP, ImageMagick or dcraw, feh will only load/convert them once and re-use the cached file on subsequent slideshow passes.  This option disables the cache.  It is also disabled when --reload is used.  Use it if you rely on frequently changing files loaded via one of these sources.  Note that it will impair performance.
--no-jump-on-resort Don't jump to the first image after resorting the filelist.
-N, --no-menus Don't load or show any menus.
--no-screen-clip By default, window sizes are limited to the screen size.  With this option, windows will have the size of the image inside them.  Note that they may become very large this way, making them unmanageable in certain window managers.
--no-xinerama (optional feature, enabled in this build) Disable Xinerama support.
--on-last-slide hold | quit | resume Select behaviour when trying to select the next image on the last slide (or the previous image on the first slide) in a slide show.
With hold, feh will stop advancing images in this case and continue displaying the first/last image, respectively.  This is intended for linear slide shows.  Behaviour is unspecified when using other navigation commands than previous and next image.
quit will cause feh to quit when trying to advance past the last image in the slide show.
resume is the default behaviour: On the last (first) image, feh will wrap around to the first (last) image.
-j, --output-dir directory Save files to directory when using --keep-http or the save_image or save_filelist command.  By default, files are saved in the current working directory.
-p, --preload Preload images.  This doesn't mean hold them in RAM, it means run through them and eliminate unloadable images first.  Otherwise they will be removed as you flick through.  This also analyses the images to get data for use in sorting, such as pixel size, type etc.  A preload run will be automatically performed if you specify one of these sort modes.
-q, --quiet Don't report non-fatal errors for failed loads.  Verbose and quiet modes are not mutually exclusive, the first controls informational messages, the second only errors.
-z, --randomize When viewing multiple files in a slideshow, randomize the file list before displaying.  The list is re-randomized whenever the slideshow cycles (that is, transitions from last to first image).
-r, --recursive Recursively expand any directories in the command line arguments to the content of those directories, all the way down to the bottom level.
--no-recursive Don't recursively expand any directories.  This is the default, but this option is useful to override themes containing --recursive.
-R, --reload int Reload filelist and current image after int seconds.  Useful for viewing HTTP webcams or frequently changing directories.  (Note that filelist reloading is still experimental.) Set to zero to disable any kind of automatic reloading.
If an image is removed, feh will either show the next one or quit. However, if an image still exists, but can no longer be loaded, feh will continue to try loading it.
Setting this option causes inotify-based auto-reload to be disabled.  Reload is not supported in montage, index, or thumbnail mode.
-n, --reverse Reverse the sort order.  Use this to invert the order of the filelist.  E.g. to sort in reverse width order, use -nSwidth.
-., --scale-down Scale images to fit window geometry (defaults to screen size when no geometry was specified).  Note that the window geometry is not updated when changing images at the moment.  This option is recommended for tiling window managers.  This option is ignored when in fullscreen and thumbnail list mode.
In tiling environments, this also causes the image to be centered in the window.
--scroll-step count Scroll count pixels whenever scroll_up, scroll_down, scroll_left or scroll_right is pressed.  Note that this option accepts negative numbers in case you need to reverse the scroll direction.  See KEYS CONFIG SYNTAX for how to reverse it permanently.  Default: 20
-D, --slideshow-delay float For slideshow mode, wait float seconds between automatically changing slides.  Useful for presentations.  Specify a negative number to set the delay (which will then be float * (-1)), but start feh in paused mode.
-S, --sort sort_type Sort file list according to image parameters.  Allowed sort types are: name, filename, dirname, mtime, width, height, pixels, size, format.  For sort modes other than name, filename, dirname, or mtime, a preload run is necessary, causing a delay proportional to the number of images in the list.
mtime starts with the most recently modified image.  width, height, pixels and size start with the smallest.  Use --reverse to sort by oldest or largest first.
For name, filename, and dirname you can use --version-sort to sort numbers naturally, so that e.g. 10.jpg comes after 2.jpg.
-|, --start-at filename Start the filelist at filename.  If no other files or filelists were specified on the command line, feh will first load all files from the directory in which filename resides.  This way, it's possible to look at a specific image and use the next / prev keys to browse through the directory.  See USAGE EXAMPLES for examples. If filename is a remote URL and no files or filelists were specified, feh will show filename and not attempt to load additional files or directories.
Note: If you use relative paths in your filelist, filename should also be a relative path.  If you use absolute paths, it should also be an absolute path.  If feh cannot find an exact match, it will compare basenames (filenames without the directory suffix).  This may lead to mismatches if several files in your filelist have the same basename.
-T, --theme theme Load options from config file with name theme - see THEMES CONFIG SYNTAX for more info.  Note that command line options always override theme options.  The theme can also be set via the program name (e.g. with symlinks), so by default feh will look for a "feh" theme.
-t, --thumbnails Same as Index mode, but the thumbnails are clickable image launchers.  Note that --fullscreen and --scale-down do not affect the thumbnail window.  They do, however, work for image windows launched from thumbnail mode.  Also supports INDEX AND THUMBNAIL MODE OPTIONS as well as MONTAGE MODE OPTIONS.
-~, --thumb-title string Set title for windows opened from thumbnail mode.  See also FORMAT SPECIFIERS.
-^, --title title Set window title.  Applies to all windows except those opened from thumbnail mode.  See FORMAT SPECIFIERS.
-u, --unloadable Don't display images.  Just print out their names if imlib2 can NOT successfully load them.  Returns false if at least one image was loadable.
-V, --verbose output useful information, progress bars, etc.
-v, --version output version information and exit.
--version-sort When combined with --sort name, --sort filename, or --sort dirname: use natural sorting for file and directory names.  In this mode, filenames are sorted as an ordinary human would expect, e.g. "2.jpg" comes before "10.jpg".  Note that this option only has an effect when a sort mode is set using --sort.
--window-id windowid Draw to an existing X11 window by its ID windowid.  This option is intended for use with software such as xcreensaver or xsecurelock, which provide a window for other applications to draw into. Unexpected things will happen if you specify a window belonging to software which does not expect feh to draw into it or attempt to use options or keybindings which affect window attributes, such as full-screen mode.
--xinerama-index monitor (optional feature, enabled in this build) Override feh's idea of the active Xinerama monitor.  May be useful in certain circumstances where the window manager places the feh window on Xinerama monitor A while feh assumes that it will be placed on monitor B.
In background setting mode: When used with any option other than --bg-tile: Only set wallpaper on monitor.  All other monitors will be filled black/white.  This is most useful in a Xinerama configuration with overlapping monitors.  For instance, assume you have two overlapping displays (index 0 and 1), where index 0 is smaller.  To center a background on the display with index 0 and fill the extra space on index 1 black/white, use "--xinerama-index 0" when setting the wallpaper.
Use xrandr --listmonitor to determine how Xinerama monitor IDs map to screens/monitors in your setup.
--zoom percent | max | fill Zoom images by percent when in full screen mode or when window geometry is fixed.  When combined with --auto-zoom, zooming will be limited to the specified percent.  Specifying max is like setting --auto-zoom, using fill makes feh zoom the image like the --bg-fill mode.
--zoom-step percent Zoom images in and out by percent (default: 25) when using the zoom keys and buttons.
These additional options can be used for index, montage and (partially) thumbnail mode.
-a, --alpha int When drawing thumbnails onto the background, set their transparency level to int (0 - 255).
-b, --bg file | trans Use file as background for your montage.  With this option specified, the montage size will default to the size of file if no size restrictions were specified.  Alternatively, if file is "trans", the background will be made transparent.
-X, --ignore-aspect By default, the montage thumbnails will retain their aspect ratios, while fitting into thumb-width/-height.  This options forces them to be the size set by --thumb-width and --thumb-height.  This will prevent any empty space in the final montage.
-H, --limit-height pixels Limit the height of the montage.
-W, --limit-width pixels Limit the width of the montage, defaults to 800 pixels.
If both --limit-width and --limit-height are specified, the montage will be exactly width x height pixels in dimensions.
-o, --output file Save the created montage to file.
-O, --output-only file Just save the created montage to file without displaying it.
-s, --stretch Normally, if an image is smaller than the specified thumbnail size, it will not be enlarged.  If this option is set, the image will be scaled up to fit the thumbnail size.  Aspect ratio will be maintained unless --ignore-aspect is specified.
-E, --thumb-height pixels Set thumbnail height.
-y, --thumb-width pixels Set thumbnail width.
In addition to MONTAGE MODE OPTIONS --alpha, --bg, --limit-height, --limit-width, --output, --output-only, --thumb-height, --thumb-width, the following options can be used.
--index-info format Show image information based on format below thumbnails in index / thumbnail mode.  See FORMAT SPECIFIERS.  May contain newlines.  Use "--index-info ''" to display thumbnails without any info text
Note: If you specify image-related formats (such as %w or %s), feh needs to load all images to calculate the dimensions of its own window.  So when using them with many files, it will take a while before a feh window becomes visible.  Use --preload to get a progress bar.
-@, --title-font font Set font to print a title on the index, if no font is specified, no title will be printed.
-J, --thumb-redraw n Redraw thumbnail window every n images while generating thumbnails. Redrawing takes quite long, so the default is 10.  Set n = 1 to update the thumbnail window immediately.  With n = 0, there will only be one redraw once all thumbnails are loaded.
In many desktop environments, feh can also be used as a background setter. Unless you pass the --no-fehbg option, it will write a script to set the current background to ~/.fehbg.  So to have your background restored every time you start X, you can add "~/.fehbg &" to your X startup script (such as ~/.xinitrc).  Note that the commandline written to ~/.fehbg always includes the --no-fehbg option to ensure that it is not inadvertently changed by differences in X11 screen layout or similar.
Note that feh does not support setting the wallpaper of GNOME shell desktops.  In this environment, you can use "gsettings set org.gnome.desktop.background picture-uri file:///path" instead.
For --bg-center, --bg-fill, and --bg-max, you can use --geometry to specify an offset from one side of the monitor instead of centering the image. Positive values will offset from the left/top side, negative values from the bottom/right.  +0 and -0 are both valid and distinct values.
Note that all options except --bg-tile support Xinerama.  For instance, if you have multiple monitors connected and use e.g.  --bg-center, feh will center or appropriately offset the image on each monitor.  You may even specify more than one file, in that case, the first file is set on monitor 0, the second on monitor 1, and so on.  Use xrandr --listmonitor to determine how Xinerama monitor IDs map to screens / monitors in your setup.
Use --no-xinerama to treat the whole X display as one monitor when setting wallpapers.  You may also use --xinerama-index to use feh as a background setter for a specific monitor.
--bg-center Center the file on the background.  If it is too small, it will be surrounded by a border as specified by --image-bg.
--bg-fill Like --bg-scale, but preserves aspect ratio by zooming the image until it fits.  Either a horizontal or a vertical part of the image will be cut off
--bg-max Like --bg-fill, but scale the image to the maximum size that fits the screen with borders on one side.  The border color can be set using --image-bg.
--bg-scale Fit the file into the background without repeating it, cutting off stuff or using borders.  But the aspect ratio is not preserved either
--bg-tile Tile (repeat) the image in case it is too small for the screen
--no-fehbg Do not write a ~/.fehbg file
%a      Information about slideshow state (playing/paused)
%f      Image path/filename
%F      Escaped image path/filename (for use in shell commands)
%g      w,h window dimensions in pixels (mnemonic: geometry)
%h      Image height
%l      Total number of files in filelist
%L      Temporary copy of filelist.  Multiple uses of %L within the same format string will return the same copy.
%m      Current mode
%n      Image name
%N      Escaped image name
%o      x,y offset of top-left image corner to window corner in pixels
%p      Number of image pixels
%P      Number of image pixels in human-readable format with k/M (kilopixels / megapixels) suffix
%r      Image rotation.  A half right turn equals pi.
%s      Image size in bytes
%S      Human-readable image size (kB / MB)
%t      Image format
%u      Number of current file
%w      Image width
%v      feh version
%V      Process ID
%z      Current image zoom, rounded to two decimal places
%Z      Current image zoom, higher precision
%%      A literal %
feh has three config files: themes for theme definitions, keys for key bindings and buttons for mouse button bindings.  It will try to read them from $XDG_CONFIG_HOME/feh/, which (when XDG_CONFIG_HOME is unset) defaults to ~/.config/feh/.  If the files are not found in that directory, it will also try /etc/feh/.
All config files treat lines starting with a "#" character as comments. Comments at the end of a line are not supported.
.config/feh/themes allows the naming of option groups, called themes.
It takes entries of the form "theme options ...", where theme is the name of the entry and options are the options which will be applied when the theme is used.
Note that the option parser does not behave like a normal shell: filename expansion and backslash escape sequences are not supported and passed to feh's option parser as-is.  However, quoting of arguments is respected and can be used for arguments with whitespace.  So, the sequence "--info "foo bar"" works as intended (that is, it display the string "foo bar"), whereas the option string "--info foo\ bar" will only display "foo\" and complain about the file bar not existing.  Please keep this in mind when writing theme files.
An example entry is "imagemap -rVq --thumb-width 40 --thumb-height 30 --index-info '%n\n%wx%h'".
You can use this theme in two ways.  Either call "feh -Timagemap *.jpg", or create a symbolic link to feh with the name of the theme you want it to use.  For the example above, this would be "ln -s `which feh ` ~/bin/imagemap".  Now just run "imagemap *.jpg" to use these options.
Note that you can split a theme over several lines by placing a backslash at the end of an unfinished line.  A single option-argument-pair must not span multiple lines.  A single line must not be longer than 1023 characters, but there's no upper limit for the length of a theme.
Command line options always override theme options.
.config/feh/keys defines key bindings.  It has entries of the form "action [key1 [key2 [key3]]]".
Each key is an X11 keysym name as shown by xev(1), like "Delete".  It may optionally start with modifiers for things like Control, in which case key looks like mod-keysym (for example "C-Delete" for Ctrl+Delete or "C-1-Delete" for Ctrl+Alt+Delete)
Available modifiers are C for Control, S for Shift and 1, 4 for Mod1 and Mod4.  To match an uppercase letter like "S" instead of "s", the Shift modifier is not required.
Specifying an action without any keys unbinds it (i.e. the default bindings are removed).
Note: Do not use the same keybinding for multiple actions.  When binding an action to a new key (or mouse button), make sure to unbind it from its previous action, if present.  feh does not check for conflicting bindings, so their behaviour is undefined.
For a list of the action names, see KEYS.  Note that not all of the key names used there correspond to X11 keysyms.  Most notably, page up (Prior / Page_Up), page down (Next / Page_Down) and the keypad keys (KP_*) do not.
The following actions and default key bindings can be used in an image window.  (The strings in [square brackets] are the config action names). If feh is running inside a terminal and its standard input is not used for images or filelists, key input from the terminal is also accepted. However, terminal input support is currently limited to most alphanumeric characters (0-9 a-z A-Z and some more), arrow keys, return and backspace. The Alt (Mod1) modifier is also supported.
a [toggle_actions] Toggle actions display (see --draw-actions)
A [toggle_aliasing] Enable/Disable anti-aliasing
c [toggle_caption] Caption entry mode.  If --caption-path has been specified, then this enables caption editing.  The caption at the bottom of the screen will turn yellow and can be edited.  Hit return to confirm and save the caption, or escape to cancel editing.  Note that you can insert an actual newline into the caption using ⟨Ctrl+return⟩.
d [toggle_filenames] Toggle filename display (see --draw-filename)
e [toggle_exif] (optional feature, available in this build) Toggle EXIF tag display
f [toggle_fullscreen] Toggle fullscreen
g [toggle_fixed_geometry] Enable/Disable automatic window resize when changing images.
h [toggle_pause] Pause/Continue the slideshow.  When it is paused, it will not automatically change slides based on --slideshow-delay.
i [toggle_info] Toggle info display (see --info)
k [toggle_keep_vp] Toggle zoom and viewport keeping.  When enabled, feh will keep zoom and X, Y offset when switching images.
L [save_filelist] Save the current filelist as "feh_PID_ID_filelist".  It is saved in the directory specified by --output-dir, if set, and in the current working directory otherwise.
m [toggle_menu] Show menu.  Use the arrow keys and return to select items, and ⟨escape⟩ to close the menu.
n, ⟨space⟩, ⟨Right⟩ [next_img] Show next image.  Selects the next image in thumbnail mode.
o [toggle_pointer] Toggle pointer visibility
p, ⟨BackSpace⟩, ⟨Left⟩ [prev_img] Show previous image.  Selects the previous image in thumbnail mode.
q, ⟨Escape⟩ [quit] Quit feh
r [reload_image] Reload current image.  Useful for webcams
s [save_image] Save the current image as "feh_PID_ID_FILENAME".  It is saved in the directory specified by --output-dir, if set, and in the current working directory otherwise.
w [size_to_image] Change window size to fit current image size (plus/minus zoom, if set).  In scale-down and fixed-geometry mode, this also updates the window size limits.
x [close] Close current window
z [jump_random] Jump to a random position in the current filelist
Z [toggle_auto_zoom] Toggle auto-zoom.
[, ] [prev_dir, next_dir] Jump to the first image of the previous or next sequence of images sharing a directory name in the current filelist.  Use --sort dirname if you would like to ensure that all images in a directory are grouped together.
<, > [orient_3, orient_1] rotate the image 90 degrees (counter)clockwise.
When --edit is used, this also rotates the image in the underlying file.  Rotation is lossless, but may create artifacts in some image corners when used with JPEG images.  Rotating in the reverse direction will make them go away.  See jpegtran(1) for more about lossless JPEG rotation.  Note: feh assumes that this feature is used to normalize image orientation.  For JPEG images, it will unconditionally set the EXIF orientation tag to 1 ("0,0 is top left") after every rotation.  See jpegexiforient(1) for details on how to change this flag.
_ [flip] Vertically flip image.  When --edit is used, this also flips the image in the underlying file (see above).
| [mirror] Horizontally flip image.  When --edit is used, this also flips the image in the underlying file (see above).
0 .. 9 [action_0 .. action_9] Execute the corresponding action (0 = --action, 1 = --action1 etc.)
⟨Return⟩ [action_0] Run the command defined by --action
⟨Home⟩ [jump_first] Show first image
⟨End⟩ [jump_last] Show last image
⟨page up⟩ [jump_fwd] Go forward ~5% of the filelist
⟨page down⟩ [jump_back] Go backward ~5% of the filelist
+ [reload_plus] Increase reload delay by 1 second
- [reload_minus] Decrease reload delay by 1 second
⟨Delete⟩ [remove] Remove current file from filelist
⟨Ctrl+Delete⟩ [delete] Remove current file from filelist and delete it
⟨keypad Left⟩, ⟨Ctrl+Left⟩ [scroll_left] Scroll to the left
⟨keypad Right⟩, ⟨Ctrl+Right⟩ [scroll_right] Scroll to the right
⟨keypad up⟩, ⟨Ctrl+Up⟩ [scroll_up] Scroll up
⟨keypad Down⟩, ⟨Ctrl+Down⟩ [scroll_down] Scroll down.  Note that the scroll keys work without anti-aliasing for performance reasons; hit the render key after scrolling to anti-alias the image.
⟨Alt+Left [scroll_left_page]⟩ Scroll to the left by one page
⟨Alt+Right [scroll_right_page]⟩ Scroll to the right by one page
⟨Alt+Up [scroll_up_page]⟩ Scroll up by one page
⟨Alt+Down [scroll_down_page]⟩ Scroll down by one page
R, ⟨keypad begin⟩ [render] Anti-alias the image.  Opens the currently selected image in thumbnail mode.
⟨keypad +⟩, ⟨Up⟩ [zoom_in] Zoom in
⟨keypad -⟩, ⟨Down⟩ [zoom_out] Zoom out
*, ⟨keypad *⟩ [zoom_default] Zoom to 100%
/, ⟨keypad /⟩ [zoom_fit] Zoom to fit the window size
! [zoom_fill] Zoom to fill the window size like --bg-fill
MENU KEYS The following keys bindings are used for the feh menu:
⟨Escape⟩ [menu_close] Close the menu
⟨Up⟩ [menu_up] Highlight previous menu item
⟨Down⟩ [menu_down] Highlight next menu item
⟨Left⟩ [menu_parent] Highlight parent menu item
⟨Right⟩ [menu_child] Highlight child menu item
⟨Return⟩, ⟨space⟩ [menu_select] Select highlighted menu item
.config/feh/buttons.  This works like the keys config file: the entries are of the form "action [binding]".
Each binding is a button number.  It may optionally start with modifiers for things like Control, in which case binding looks like mod-button (for example C-1 for Ctrl + Left button).
Note: Do not use the same button for multiple actions.  feh does not check for conflicting bindings, so their behaviour is undefined.  Either unbind the unwanted action, or bind it to another unused button.  The order in which you bind / unbind does not matter, though.
For the available modifiers, see KEYS CONFIGURATION SYNTAX.
BUTTONS In an image window, the following buttons may be used (The strings in [square brackets] are the config action names).  Additionally, all actions specified in the KEYS section can also be bound to a button.
unbound [reload] Reload current image
1 ⟨left mouse button⟩ [pan] pan the current image
2 ⟨middle mouse button⟩ [zoom] Zoom the current image
3 ⟨right mouse button⟩ [toggle_menu] Toggle menu
4 ⟨mousewheel down⟩ [prev_img] Show previous image
5 ⟨mousewheel up⟩ [next_img] Show next image
Ctrl+1 [blur] Blur current image
Ctrl+2 [rotate] Rotate current image
unbound [zoom_in] Zoom in
unbound [zoom_out] Zoom out
Default Bindings: When viewing an image, mouse button 1 pans the image (moves it around) or, when only clicked, moves to the next image (slideshow mode only).  Quick drags with less than 2px of movement per axis will be treated as clicks to aid graphics tablet users.  Mouse button 2 zooms (click and drag left->right to zoom in, right->left to zoom out, click once to restore zoom to 100%) and mouse button 3 opens the menu.
Ctrl+Button 1 blurs or sharpens the image (drag left to blur, right to sharpen); Ctrl+Button 2 rotates the image around the center point.
A note about pan and zoom modes: In pan mode, if you reach a window border but haven't yet panned to the end of the image, feh will warp your cursor to the opposite border so you can continue panning.
When clicking the zoom button and immediately releasing it, the image will be back at 100% zoom.  When clicking it and moving the mouse while holding the button down, the zoom will be continued at the previous zoom level. The zoom will always happen so that the pixel on which you entered the zoom mode remains stationary.  So, to enlarge a specific part of an image, click the zoom button on that part.
In slideshow and multiwindow mode, feh handles the following signals:
SIGUSR1 Slideshow mode: switch to next image; reload current image if the slideshow consists of a single file.  Multiwindow mode: reload all images.
SIGUSR2 Slideshow mode: switch to previous image; reload current image if the slideshow consists of a single file.  Multiwindow mode: reload all images.
Here are some examples of useful option combinations.  See also: ⟨https://feh.finalrewind.org/examples/⟩
feh ~/Pictures Show all images in ~/Pictures
feh -r ~/Pictures Recursively show all images found in ~/Pictures and subdirectories
feh -rSfilename --version-sort ~/Pictures Same as above, but sort naturally.  By default, feh will show files in the string order of their names, meaning e.g.  "foo 10.jpg" will come before "foo 2.jpg".  In this case, they are instead ordered as a human would expect.
feh -t -Sfilename -E 128 -y 128 -W 1024 ~/Pictures Show 128x128 pixel thumbnails, limit window width to 1024 pixels.
feh -t -Sfilename -E 128 -y 128 -W 1024 -P -C /usr/share/fonts/truetype/ttf-dejavu/ -e DejaVuSans/8 ~/Pictures Same as above, but enable thumbnail caching and use a smaller font.
feh -irFarial/14 -O index.jpg ~/Pictures Make an index print of ~/Pictures and all directories below it, using 14 point Arial to write the image info under each thumbnail. Save the image as index.jpg and don't display it, just exit.  Note that this even works without a running X server
feh --unloadable -r ~/Pictures Print all unloadable images in ~/Pictures, recursively
feh -f by_width -S width --reverse --list . Write a list of all images in the directory to by_width, sorted by width (widest images first)
feh -w ~/Pictures/holidays Open each image in ~/Pictures/holidays in its own window
feh -FD5 -Sname ~/Pictures/presentation Show the images in .../presentation, sorted by name, in fullscreen, automatically change to the next image after 5 seconds