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

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

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.)

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

Same as but write named frames to files `xxx.name' instead of `xxx.frame-number'.

General options control the information gifsicle prints and where it writes its output. The info options and can be turned off with

Like but also print information about input files' colormaps. is a synonym for

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

Print usage information and exit.

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

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

Print progress information (files read and written) to standard error.

Suppress all warning messages.

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

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.

Accept concatenated GIF files (multiple GIF image files concatenated into one big file; each image file may, of course, contain multiple frames). 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.

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 specifications.

#num

Select frame num. (The first frame is Negative numbers count backwards from the last frame, which is

#num1-num2

Select frames num1 through num2.

#num1-

Select frames num1 through the last frame.

#name

Select the frame named name.

For example, gifsicle happy.gif will use all of `happy.gif's frames, while gifsicle happy.gif '#0' will only use the first. (Note the single quotes around the frame specification. The `#' character has special meaning for many shells, so you may need to quote it.)

The action performed with the selected frames depends on the current mode. In merge mode, only the selected frames are merged into the output 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 insert new frames into an animation or replace or delete frames that already exist. Some thingsEfor example, changing one frame in an animationEare difficult to express with frame selections, but easy with frame changes.

Delete frames from the input GIF.

Insert other-GIFs before frame in the input GIF.

Append other-GIFs to the input GIF.

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 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 modify input imagesEby changing their interlacing, transparency, and cropping, for example. Image options have three forms: and The form selects a value for the feature, the form turns off the feature, and the form means that the feature's value is copied from each input. The default is always For example, sets the background color to blue, turns the background color off (by setting it to 0), and uses input images' existing background colors. You can give each option multiple 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.

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

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+widthxheight 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 example, will shave 2 pixels off each side of the input image. (Note: This behavior is different from versions 1.30 and before.) Cropping takes place on the raw input image, before any rotation, flipping, resizing, or positioning.

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

Flip the following frames horizontally or vertically.

Turn interlacing on.

Set the output logical screen to widthxheight. sets the output logical screen to the size of the largest output frame, while sets the output logical screen to the largest input logical screen. is a synonym for

Set the following frames' positions to (x,y). means Normally, 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 the following frames by 90, 180, or 270 degrees. turns off any rotation.

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

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

Add a comment, text, to the output GIF. The comment will be placed before the next frame in the stream. and affect all the images following, and apply only to input GIF comments, not ones added with

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. (or and affect all the images following, and apply only to input GIF extensions.

Set the next frame's name to text. This name is stored as an extension in the output GIF (extension number 0xCE, followed by the characters of the frame name). and affect all the images following. They apply only to input GIF names, not ones added with

Animation options apply to GIF animations, or to individual frames in GIF animations. As with image options, most animation options have three forms, and and you can give animation 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.

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

Set the disposal method for the following frames to method. Method can be a number between 0 and 7 (although only 0 through 3 are generally meaningful), or one of these names: none, asis, background (or bg), previous. means

Set the Netscape loop extension to count. Count is an integer, or forever to loop endlessly. If you supply a option without specifying count, Gifsicle will use forever. (the default) turns off looping. Set the loop count to one less than the number of times you want the animation to run. An animation with will show every frame once; will loop once, thus showing every frame twice; and so forth. Note that is equivalent to not

Optimize output GIF animations for space. Level determines how much optimization is done. There are currently two levels:

Stores only the changed portion of each image. This is the default.

Also uses transparency to shrink the file further.

There is no option.

Unoptimize GIF animations into an easy-to-edit form. GIF animations are often optimized (see to make them smaller and faster to load, which unfortunately makes them difficult to edit. 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 option.

Whole-GIF options effect entire GIFs as they are read or written. They can be turned off with

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

Change color1 to color2 in the following input GIFs. (The color arguments have the same forms as in the 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 They all take effect as an input GIF is read. cancels all color changes.

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 an adaptive group of colors is chosen from the existing color table. You can affect this process with the option. Gifsicle may need to add an additional color (making num+1 in all) if there is transparency in the image.

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. is a synonym for

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

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.

Same as

Same as

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 optimization.

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 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.

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 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