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 GIFSICLE(1)                    Version 1.67                     GIFSICLE(1)
                                 5 May 2012



 NAME
      gifsicle - manipulates GIF images and animations

 SYNOPSIS
      gifsicle [options, frames, and filenames]...

 DESCRIPTION
      gifsicle is a powerful command-line program for creating, editing,
      manipulating, and getting information about GIF images and animations.

 INTRODUCTION
      Without options, gifsicle acts like a filter: you feed it a GIF on
      standard input, and it writes that GIF on standard output. That means
      these two commands do the same thing:

           gifsicle < in.gif > out.gif
           gifsicle < in.gif | gifsicle | gifsicle > out.gif

      Not too interesting. Most times you'll tell gifsicle to alter its
      inputs by giving it command line options. The -i option, for example,
      tells it to interlace its input files:

           gifsicle -i < pic.gif > interlaced-pic.gif

      To modify GIF files in place, you should use the --batch option. With
      --batch, gifsicle will modify the files you specify instead of writing
      a new file to the standard output. To interlace all the GIFs in the
      current directory, you could say:

           gifsicle --batch -i *.gif

      gifsicle is good at creating and manipulating GIF animations. The
      simplest way to create an animation is to give more than one input
      file, which gifsicle will combine to create a ``flipbook'' animation:

           gifsicle pic1.gif pic2.gif pic3.gif > animation.gif

      Use options like --delay, --loopcount, and --optimize to tune your
      animations; see their descriptions for more details.

      The bulk of this manual page indexes gifsicle's options and describes
      them in gory detail. New users may want to skip to the Examples
      section at the end.

 CONCEPT INDEX
      This index is meant to help you find options that do what you want.
      Concepts are on the left, relevant gifsicle options are on the right.

      Animations, changing     frame selections, frame changes, etc.
         disposal              --disposal




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         looping               --loopcount
         portions of           frame selections
         smaller               --optimize, --colors
         speed                 --delay
      Bad output               --careful
      Background color         --background
      Colors, changing         --change-color, --use-colormap, --dither,
                               --transform-colormap
         reducing number       --colors, --dither
      Comments                 --comment
      Extensions               --extension, --app-extension,
                               --extension-info
      File size                --optimize, --unoptimize, --colors
      Image transformations
         cropping              --crop, --crop-transparency
         flipping              --flip-*
         resizing              --resize, --scale
         rotating              --rotate-*
      Grayscale                --use-colormap
      Interlacing              --interlace
      Positioning frames       --position
      Screen, logical          --logical-screen
      Selecting frames         frame selections (like '#0')
      Transparency             --transparent
      Warnings                 --no-warnings
      Web-safe palette         --use-colormap

 COMMAND LINE
      gifsicle's command line consists of GIF input files and options. Most
      options start with a dash (-) or plus (+); frame selections, a kind of
      option, start with a number sign (#). Anything else is a GIF input
      file.

      gifsicle reads and processes GIF input files in order. If no GIF input
      file is given, or you give the special filename `-', it reads from the
      standard input.

      gifsicle exits with status 0 if there were no errors and status 1 oth-
      erwise.

 OPTIONS
      Every option has a long form, `--long-descriptive-name'.  You don't
      need to type the whole long descriptive name, just enough to make it
      unambiguous.

      Some options also have a short form, `-X'.  You can combine short op-
      tions if they don't take arguments: `-IIb' is the same as `-I -I -b'.
      But be careful with options that do take arguments: `-cblah' means `-c
      blah', not `-c -b -l -a -h'.





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      Many options also have a converse, `--no-option', which turns off the
      option. You can turn off a short option `-X' by saying `+X' instead.

    Mode Options
      Mode options tell gifsicle what kind of output to generate. There can
      be at most one, and it must precede any GIF inputs.

      --merge, -m
           Combine all GIF inputs into one file with multiple frames and
           write that file to the standard output. This is the default mode.

      --batch, -b
           Modify each GIF input in place by reading and writing to the same
           filename.  (GIFs read from the standard input are written to the
           standard output.)

      --explode, -e
           Create an output GIF for each frame of each input file. The out-
           put GIFs are named `xxx.000', `xxx.001', and so on, where `xxx'
           is the name of the input file (or whatever you specified with
           `--output') and the numeric extension is the frame number.

      --explode-by-name, -E
           Same as --explode, but write any named frames to files `xxx.name'
           instead of `xxx.frame-number'.  Frames are named using the
           `--name' option.

    General Options
      General options control the information gifsicle prints and where it
      writes its output. The info options and --verbose can be turned off
      with `--no-X'.

      --color-info
           Like --info, but also print information about input files' color-
           maps.  --cinfo is a synonym for --color-info.

      --extension-info
           Like --info, but also print any unrecognized GIF extensions in a
           hexdump(1)-like format.  --xinfo is a synonym for -
           --extension-info.

      --help, -h
           Print usage information and exit.

      --info, -I
           Print a human-readable description of each input GIF to the stan-
           dard output, or whatever file you specify with -o.  This option
           suppresses normal output, and cannot be combined with mode op-
           tions like --batch.  If you give two --info or -I options, howev-
           er, normal output is not suppressed; information will be printed
           on standard error, and you can supply a mode option.



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      -o file
      --output file
           Send output to file.  The special filename `-' means the standard
           output.

      --verbose, -V
           Print progress information (files read and written) to standard
           error.

      --no-warnings, -w
           Suppress all warning messages.

      --version
           Print the version number and some short non-warranty information
           and exit.

      --conserve-memory
           Conserve memory usage at the expense of processing time. This may
           be useful if you are processing large GIFs on a computer without
           very much memory.

      --nextfile
           Allow input files to contain multiple concatenated GIF images. If
           a filename appears multiple times on the command line, gifsicle
           will read a new image from the file each time. This option can
           help scripts avoid the need for temporary files. For example, to
           create an animated GIF with three frames with different delays,
           you might run "gifsicle --nextfile -d10 - -d20 - -d30 - >
           out.gif" and write the three GIF images, in sequence, to
           gifsicle's standard input.

      --multifile
           Like --nextfile, but read as many GIF images as possible from
           each file. This option is intended for scripts. For example, to
           merge an unknown number of GIF images into a single animation,
           run "gifsicle --multifile - > out.gif" and write the GIF images,
           in sequence, to gifsicle's standard input.  Any frame selections
           apply only to the last file in the concatenation.

    Frame Selections
      A frame selection tells gifsicle which frames to use from the current
      input file. They are useful only for animations, as non-animated GIFs
      only have one frame. Here are the acceptable forms for frame specifi-
      cations.

      #num         Select frame num. (The first frame is `#0'.  Negative
                   numbers count backwards from the last frame, which is
                   `#-1'.)
      #num1-num2   Select frames num1 through num2.
      #num1-       Select frames num1 through the last frame.




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      #name        Select the frame named name.

      The `#' character has special meaning for many shells, so you general-
      ly need to quote it.

      For example,
           gifsicle happy.gif "#0"
      uses the first frame from happy.gif;
           gifsicle happy.gif "#0-2"
      uses its first three frames; and
           gifsicle happy.gif "#-1-0"
      uses `happy.gif's frames in reverse order (starting from frame #-1 --
      the last frame -- and ending at frame #0 -- the first).

      The action performed with the selected frames depends on the current
      mode. In merge mode, only the selected frames are merged into the out-
      put GIF. In batch mode, only the selected frames are modified; other
      frames remain unchanged. In explode mode, only the selected frames are
      exploded into output GIFs.

    Frame Change Options
      Frame change options insert new frames into an animation or replace or
      delete frames that already exist. Some things -- for example, changing
      one frame in an animation -- are difficult to express with frame
      selections, but easy with frame changes.

      --delete frames [frames...]
           Delete frames from the input GIF.

      --insert-before frame other-GIFs
           Insert other-GIFs before frame in the input GIF.

      --append other-GIFs
           Append other-GIFs to the input GIF.

      --replace frames other-GIFs
           Replace frames from the input GIF with other-GIFs.

      --done
           Complete the current set of frame changes.

      The frames arguments are frame selections (see above). These arguments
      always refer to frames from the original input GIF. So, if `a.gif' has
      3 frames and `b.gif' has one, this command
           gifsicle a.gif --delete "#0" --replace "#2" b.gif
      will produce an output animation with 2 frames: `a.gif' frame 1, then
      `b.gif'.

      The other-GIFs arguments are any number of GIF input files and frame
      selections.  These images are combined in merge mode and added to the
      input GIF.  The other-GIFs last until the next frame change option, so



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      this command replaces the first frame of `in.gif' with the merge of
      `a.gif' and `b.gif':
           gifsicle -b in.gif --replace "#0" a.gif b.gif

      This command, however, replaces the first frame of `in.gif' with
      `a.gif' and then processes `b.gif' separately:
           gifsicle -b in.gif --replace "#0" a.gif --done b.gif

      Warning: You shouldn't use both frame selections and frame changes on
      the same input GIF.

    Image Options
      Image options modify input images -- by changing their interlacing,
      transparency, and cropping, for example. Image options have three
      forms: `--X', `--no-X', and `--same-X'.  The `--X' form selects a
      value for the feature, the `--no-X' form turns off the feature, and
      the `--same-X' form means that the feature's value is copied from each
      input. The default is always `--same-X'.  For example, -background=
      sets the background color to blue, --no-background turns the back-
      ground color off (by setting it to 0), and --same-background uses in-
      put images' existing background colors. You can give each option mul-
      tiple times; for example,
           gifsicle -b -O2 -i a.gif --same-interlace b.gif c.gif
      will make `a.gif' interlaced, but leave `b.gif' and `c.gif' interlaced
      only if they were already.

      -B color
      --background color
           Set the output GIF's background to color.  The argument can have
           the same forms as in the --transparent option below.

      --crop x1,y1-x2,y2
      --crop x1,y1+widthxheight
           Crop the following input frames to a smaller rectangular area.
           The top-left corner of this rectangle is (x1,y1); you can give
           either the lower-right corner, (x2,y2), or the width and height
           of the rectangle. In the x1,y1+widthx form, width and height can
           be zero or negative. A zero dimension means the cropping area
           goes to the edge of the image; a negative dimension brings the
           cropping area that many pixels back from the image edge. For ex-
           ample, --crop 2,2+-2x-2 will shave 2 pixels off each side of the
           input image. Cropping takes place before any rotation, flipping,
           resizing, or positioning.

      --crop-transparency
           Crop any transparent borders off the following input frames. This
           happens after any cropping due to the --crop option. It works on
           the raw input images; for example, any transparency options have
           not yet been applied.





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      --flip-horizontal
      --flip-vertical
           Flip the following frames horizontally or vertically.

      -i
      --interlace
           Turn interlacing on.

      -S widthxheight
      --logical-screen widthxheight
           Set the output logical screen to widthxheight.
           --no-logical-screen sets the output logical screen to the size of
           the largest output frame, while --same-logical-screen sets the
           output logical screen to the largest input logical screen.
           --screen is a synonym for --logical-screen.

      -p x,y
      --position x,y
           Set the following frames' positions to (x,y).  --no-position
           means --position 0,0.  Normally, --position x,y places every
           succeeding frame exactly at x,y. However, if an entire animation
           is input, x,y is treated as the position for the animation.

      --rotate-90
      --rotate-180
      --rotate-270
           Rotate the following frames by 90, 180, or 270 degrees.
           --no-rotate turns off any rotation.

      -t color
      --transparent color
           Make color transparent in the following frames.  Color can be a
           colormap index (0-255), a hexadecimal color specification (like
           "#FF00FF" for magenta), or slash- or comma-separated red, green
           and blue values (each between 0 and 255).

    Extension Options
      Extension options add non-visual information to the output GIF. This
      includes names, comments, and generic extensions.

      -x app-name extension
      --app-extension app-name extension
           Add an application extension named app-name and with the value
           extension to the output GIF.

      -c text
      --comment text
           Add a comment, text, to the output GIF. The comment will be
           placed before the next frame in the stream.

           --no-comments and --same-comments affect all the images follow-



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           ing, and apply only to input GIF comments, not ones added with
           --comment.

      --extension number extension
           Add an extension numbered number and with the value extension to
           the output GIF.  Number can be in decimal, octal, hex, or it can
           be a single character like `n', whose ASCII value is used.

           --no-extensions (or +x) and --same-extensions affect all the im-
           ages following, and apply only to input GIF extensions.

      -n text
      --name text
           Set the next frame's name to text.  This name is stored as an ex-
           tension in the output GIF (extension number 0xCE, followed by the
           characters of the frame name).

           --no-names and --same-names affect all the images following. They
           apply only to input GIF names, not ones added with --name.

    Animation Options
      Animation options apply to GIF animations, or to individual frames in
      GIF animations. As with image options, most animation options have
      three forms, `--X', `--no-X', and `--same-X', and you can give anima-
      tion options multiple times; for example,
           gifsicle -b a.gif -d50 "#0" "#1" -d100 "#2" "#3"
      sets the delays of frames 0 and 1 to 50, and frames 2 and 3 to 100.

      -d time
      --delay time
           Set the delay between frames to time in hundredths of a second.

      -D method
      --disposal method
           Set the disposal method for the following frames to method.  A
           frame's disposal method determines how a viewer should remove the
           frame when it's time to display the next.  Method can be a number
           between 0 and 7 (although only 0 through 3 are generally meaning-
           ful), or one of these names: none (leave the frame visible for
           future frames to build upon), asis (same as "none"), background
           (or bg) (replace the frame with the background), or previous (re-
           place the frame with the area from the previous displayed frame).
           --no-disposal means --disposal=none.

      -l[count]
      --loopcount[=count]
           Set the Netscape loop extension to count.  Count is an integer,
           or forever to loop endlessly. If you supply a --loopcount option
           without specifying count, Gifsicle will use forever.
           --no-loopcount (the default) turns off looping.




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           Set the loop count to one less than the number of times you want
           the animation to run. An animation with --no-loopcount will show
           every frame once; --loopcount=1 will loop once, thus showing
           every frame twice; and so forth.  Note that --loopcount=0 is
           equivalent to --loopcount=forever, not --no-loopcount.

      -O[level]
      --optimize[=level]
           Optimize output GIF animations for space.  Level determines how
           much optimization is done; higher levels take longer, but may
           have better results. There are currently three levels:

           -O1  Stores only the changed portion of each image. This is the
                default.
           -O2  Also uses transparency to shrink the file further.
           -O3  Try several optimization methods (usually slower, sometimes
                better results).

           Other optimization flags provide finer-grained control.

           -Okeep-empty
                Preserve empty transparent frames (they are dropped by de-
                fault).

           There is no --same-optimize option.

      -U
      --unoptimize
           Unoptimize GIF animations into an easy-to-edit form.

           GIF animations are often optimized (see --optimize) to make them
           smaller and faster to load, which unfortunately makes them diffi-
           cult to edit.  --unoptimize changes optimized input GIFs into
           unoptimized GIFs, where each frame is a faithful representation
           of what a user would see at that point in the animation.

           There is no --same-unoptimize option.

    Whole-GIF Options
      Whole-GIF options effect entire GIFs as they are read or written. They
      can be turned off with `--no-option'.

      --careful
           Write slightly larger GIFs that avoid bugs in some other GIF im-
           plementations. Some Java and Internet Explorer versions cannot
           display the correct, minimal GIFs that Gifsicle produces. Use the
           --careful option if you are having problems with a particular im-
           age.

      --change-color color1 color2
           Change color1 to color2 in the following input GIFs. (The color



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           arguments have the same forms as in the -t option.) You can
           change multiple colors by giving the option multiple times. Color
           changes don't interfere with one another, so you can safely swap
           two colors with `--change-color color1 color2 --change-color
           color2 color1'.  They all take effect as an input GIF is read.
           --no-change-color cancels all color changes.

      -k num
      --colors num
           Reduce the number of distinct colors in each output GIF to num or
           less.  Num must be between 2 and 256. This can be used to shrink
           output GIFs or eliminate any local color tables.

           Unless you give --use-colormap, an adaptive group of colors is
           chosen from the existing color table.  You can affect this pro-
           cess with the --color-method option. Gifsicle may need to add an
           additional color (making num+1 in all) if there is transparency
           in the image.

      --color-method method
           Determine how a smaller colormap is chosen. There are three
           choices: diversity, the default, is xv(1)'s diversity algorithm,
           which uses a strict subset of the existing colors.
           blend-diversity is a modification of this: some color values are
           blended from a group of the existing colors.  median-cut is the
           median cut algorithm described by Heckbert.  --method is a
           synonym for --color-method.

      -f
      --dither
           This option only matters if the colormap was changed. With
           --dither on, Floyd-Steinberg error diffusion is used to approxi-
           mate any colors that were removed. This looks better, but makes
           bigger files and can cause animation artifacts, so it is off by
           default.

      --resize widthxheight
           Resize the output GIF to widthxheight.  Either width or height
           may be an underscore `_'. If the argument is widthx_, then the
           output GIF is scaled to width pixels wide without changing its
           aspect ratio. An analogous operation is performed for _xheight.
           Resizing happens after all input frames have been combined and
           before optimization. Gifsicle's resize algorithm is designed for
           speed, not quality; for best-looking results you will need to use
           other tools.

      --resize-width width
      --resize-height height
           Like --resize widthx_ and --resize _xheight respectively.





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      --resize-fit widthxheight
           Like --resize, but resizes the output GIF to fit within a rectan-
           gle with dimensions widthxheight.  The GIF's aspect ratio remains
           unchanged. No resize is performed if the GIF already fits within
           the given rectangle. Either width or height may be an underscore
           `_', which is treated as infinity.

      --resize-fit-width width
      --resize-fit-height height
           Like --resize-fit widthx_ and --resize-fit _xheight respectively.

      --scale Xfactor[xYfactor]
           Scale the output GIF's width and height by Xfactor and Yfactor.
           If Yfactor is not given, it defaults to Xfactor.  Scaling happens
           after all input frames have been combined and before optimiza-
           tion.

      --transform-colormap command
           Command should be a shell command that reads from standard input
           and writes to standard output. Each colormap in the output GIF is
           translated into text colormap format (see --use-colormap below)
           and piped to the command. The output that command generates
           (which should also be in text colormap format) will be used as
           the colormap instead.

      --use-colormap colormap
           Set the image's colormap to colormap.  Colormap can be web for
           the 216-color ``Web-safe palette''; gray for grayscale; bw for
           black-and-white; or the name of a file. That file should either
           be a text file (the format is described below) or a GIF file,
           whose global colormap will be used. If --colors=N is also given,
           an N-sized subset of colormap will be used.

           Text colormap files have a very simple format:

           # each non-comment line represents one color, "red green blue"
           # each component should be between 0 and 255
           0 0 0            # like this
           255 255 255
 EXAMPLES
      Here are a bunch of examples showing how gifsicle is commonly used.

      First, let's create an animation, `anim.gif':

           gifsicle a.gif b.gif c.gif d.gif > anim.gif

      This animation will move very quickly: since we didn't specify a de-
      lay, a browser will cycle through the frames as fast as it can. Let's
      slow it down and pause .5 seconds between frames, using the --delay
      option.




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           gifsicle --delay 50 a.gif b.gif c.gif d.gif > anim.gif

      If we also want the GIF to loop three times, we can use --loopcount:

           gifsicle -d 50 --loop=3 a.gif b.gif c.gif d.gif > anim.gif

      (Rather than type --delay again, we used its short form, -d.  Many op-
      tions have short forms; you can see them by running `gifsicle --help'.
      We also abbreviated --loopcount to --loop, which is OK since no other
      option starts with `loop'.)

      To explode `anim.gif' into its component frames:

           gifsicle --explode anim.gif
           ls anim.gif*
           anim.gif      anim.gif.000  anim.gif.001  anim.gif.002  anim.gif.003

      To optimize `anim.gif':

           gifsicle -b -O2 anim.gif

      To change the second frame of `anim.gif' to `x.gif':

           gifsicle -b --unoptimize -O2 anim.gif --replace "#1" x.gif

      --unoptimize is used since `anim.gif' was optimized in the last step.
      Editing individual frames in optimized GIFs is dangerous without
      --unoptimize; frames following the changed frame could be corrupted by
      the change.  Of course, this might be what you want.

      Note that --unoptimize and --optimize can be on simultaneously.
      --unoptimize affects input GIF files, while --optimize affects output
      GIF files.

      To print information about the first and fourth frames of `anim.gif':

           gifsicle -I "#0" "#3" < anim.gif

      To make black the transparent color in all the GIFs in the current
      directory, and also print information about each:

           gifsicle -bII --trans "#000000" *.gif

      Giving -I twice forces normal output to occur. With only one -I, the
      GIFs would not be modified.

      To change `anim.gif' to use a 64-color subset of the Web-safe palette:

           gifsicle -b --colors=64 --use-col=web anim.gif





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      To make a dithered black-and-white version of `anim.gif':

           gifsicle --dither --use-col=bw anim.gif > anim-bw.gif

      To overlay one GIF atop another -- producing a one-frame output GIF
      that looks like the superposition of the two inputs -- use gifsicle
      twice:

           gifsicle bottom.gif top.gif | gifsicle -U "#1" > result.gif

 BUGS
      Some optimized output GIFs may appear incorrectly on some GIF imple-
      mentations (for example, Java's); see the --careful option.

      Please email suggestions, additions, patches and bugs to
      ekohler@gmail.com.

 SEE ALSO
      For a tutorial on GIF images and animations, you might try some of the
      resources listed on-line at webreference.com:
      http://www.webreference.com/authoring/graphics/animation.html

 AUTHORS
      Eddie Kohler <ekohler@gmail.com>
      http://www.read.seas.harvard.edu/~kohler/
      He wrote it.

      Anne Dudfield <annied@frii.com>
      http://www.frii.com/~annied/
      She named it.

      Hans Dinsen-Hansen <dino@danbbs.dk>
      http://www.danbbs.dk/~dino/
      Adaptive tree method for GIF writing.

      http://www.lcdf.org/gifsicle/
      The gifsicle home page.

















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