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.TH GIFSICLE 1 "9 Aug 1999" "Version \*V"
.SH NAME
gifsicle \- manipulates GIF images and animations
.SH SYNOPSIS
.B gifsicle
\%[options, frames, and filenames].\|.\|.
'
.SH DESCRIPTION
.B gifsicle
is a powerful command-line program for manipulating GIF image files.
Extensive options let you control what exactly it does.
.PP
This man page assumes that you know what GIFs and GIF animations are. For a
tutorial, you might try some of the resources listed on-line at
webreference\%.com:
http://www.webreference.com/authoring/graphics/animation\|.html
'
.SH INTRODUCTION
'
Without options,
.B 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:
.Es
% \fBgifsicle < in.gif > out.gif\fR
% \fBgifsicle < in.gif | gifsicle | gifsicle > out.gif\fR
.Ee
Well, that's not very interesting! Most times you'll tell
.B gifsicle
to alter its inputs by giving it command line options. The
.OP \-i
option, for example, tells it to interlace its input files:
.Es
% \fBgifsicle -i < pic.gif > interlaced-pic.gif\fR
.Ee
.PP
This style doesn't work very well if you want to modify GIF files in
place. For that, you should use the
.OP \-\-batch
option: with
.OP \-\-batch ,
.B 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:
.Es
% \fBgifsicle \-\-batch \-i *.gif
.Ee
.PP
.B 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 
.B gifsicle
will combine to create a ``flipbook'' animation:
.Es
% \fBgifsicle pic1.gif pic2.gif pic3.gif > animation.gif\fR
.Ee
Options like
.OP \-\-delay ", " \-\-loopcount ", and " \-\-optimize
will help you tune your animations; see their descriptions for more
details.
.PP
The next sections index
.BR gifsicle 's
options and describe them in gory detail. New users may want to skip to the
Examples section at the end.
'
.SH CONCEPT INDEX
'
This index is meant to help you find options that do what you want.
Concepts are on the left, relevant
.B gifsicle
options are on the right.
'
.Sp
.PD 0
.Ix "Animations, changing" "frame selections, frame changes, etc."
.Ix "\ \ \ disposal" "\fB\-\-disposal\fP"
.Ix "\ \ \ looping" "\fB\-\-loopcount\fP"
.Ix "\ \ \ portions of" "frame selections"
.Ix "\ \ \ smaller" "\fB\-\-optimize\fP, \fB\-\-colors\fP"
.Ix "\ \ \ speed" "\fB\-\-delay\fP"
.Ix "Bad output" "\fB\-\-careful\fP"
.Ix "Background color" "\fB\-\-background\fP"
.Ix "Colors, changing" "\fB\-\-change\-color\fP, \fB\-\-use\-colormap\fP, \fB\-\-dither\fP, \fB\-\-transform\-colormap\fP"
.Ix "\ \ \ reducing number" "\fB\-\-colors\fP, \fB\-\-dither\fP"
.Ix "Comments" "\fB\-\-comment\fP"
.Ix "Extensions" "\fB\-\-extension\fP, \fB\-\-app\-extension\fP, \fB\-\-extension\-info\fP"
.Ix "File size" "\fB\-\-optimize\fP, \fB\-\-unoptimize\fP, \fB\-\-colors\fP"
.Ix "Image transformations"
.Ix "\ \ \ cropping" "\fB\-\-crop\fP"
.Ix "\ \ \ flipping" "\fB\-\-flip\-*\fP"
.Ix "\ \ \ resizing" "\fB\-\-resize\fP, \fB\-\-scale\fP"
.Ix "\ \ \ rotating" "\fB\-\-rotate\-*\fP"
.Ix "Grayscale" "\fB\-\-use\-colormap\fP"
.Ix "Interlacing" "\fB\-\-interlace\fP"
.Ix "Positioning frames" "\fB\-\-position\fP"
.Ix "Screen, logical" "\fB\-\-logical\-screen\fP"
.Ix "Selecting frames" "frame selections (like \fB'#0'\fP)"
.Ix "Transparency" "\fB\-\-transparent\fP"
.Ix "Warnings" "\fB\-\-no\-warnings\fP"
.Ix "Web-safe palette" "\fB\-\-use\-colormap\fP"
.PD
'
.SH COMMAND LINE

.BR 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.
.PP
.B 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.
.PP
.B gifsicle
exits with status 0 if there were no errors and status 1 otherwise.
'
.SH OPTIONS

Every option has a long form,
.QO \-\-long\-descriptive\-name .
You don't need to type the whole long descriptive name, just enough to
make it unambiguous.
.PP
Some options also have a short form,
.QO \-X .
You can combine short options if they don't take arguments:
.QO \-IIb
is the same as
.QO "\-I \-I \-b" .
But be careful with options that do take arguments:
.QO \-cblah
means
.QO "\-c \fRblah" ,
not
.QO "\-c \-b \-l \-a \-h" .
.PP
Many options also have a converse,
.QO \-\-no\-option ,
which turns off the option. You can turn off a short option
.QO \-X
by saying
.QO \+X
instead.
'
.\" -----------------------------------------------------------------
.SS Mode Options

Mode options tell
.B gifsicle
what kind of output to generate. There can be at most one mode option,
which must precede any GIF inputs.
.TP 5
.OP \-\-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.
'
.TP
.OP \-\-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.)
'
.TP
.OP \-\-explode ", " \-e
'
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 
.QO \-\-output )
and the numeric extension is the frame number.
'
.TP
.OP \-\-explode\-by\-name ", " \-E
'
Same as
.OP \-\-explode ","
but write named frames to files `xxx.\fIname\fR' instead of
`xxx.\fIframe-number\fR'.
'
.\" -----------------------------------------------------------------
.SS General Options

General options control what information
.B gifsicle
prints and where it writes its output. The info options and
.OP \-\-verbose
can be turned off with
.QO \-\-no\-X .
'
.Sp
.PD 0
.TP 5
.OP \-\-color\-info
'
Like
.OP \%\-\-info ,
but also print information about input files' colormaps.
.OP \%\-\-cinfo
is a synonym for
.OP \%\-\-color\-info .
'
.Sp
.TP 5
.OP \-\-extension\-info
'
Like
.OP \%\-\-info ,
but also print any unrecognized GIF extensions in a
.BR hexdump (1)-like
format.
.OP \%\-\-xinfo
is a synonym for
.OP \%\-\-extension\-info .
'
.Sp
.TP 5
.OP \-\-help ", " \-h
'
Print usage information and exit.
'
.Sp
.TP 5
.OP \-\-info ", " \-I
'
Print a human-readable description of each input GIF to the standard
output, or whatever file you specify with
.OP \-o .
This option suppresses normal output. (If you give two
.OP \-\-info
or
.OP \-I
options, the description will be printed on standard error and output will
occur as usual.)
'
.Sp
.TP
.OA \-o file
.TP
.OA \-\-output file
'
Send output to
.IR file .
The special filename `-' means the standard output.
'
.Sp
.TP
.OP \-\-verbose ", " \-v
'
Print progress information (files read and written) to standard
error.
'
.Sp
.TP
.OP \-\-no\-warnings ", " \-w
'
Suppresses all warning messages.
'
.Sp
.TP
.OP \-\-version
'
Print the version number and some short non-warranty information and exit.
'
.PD
'
.\" -----------------------------------------------------------------
.SS Frame Selections

A frame selection tells
.B 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 legal
forms for frame specifications.
.Sp
.PD 0
.TP 13
.BI # num
'
Select frame \fInum\fR. (The first frame is
.QO #0 .
Negative numbers count backwards from the last frame, which is
.QO #-1 .)
'
.TP 13
.BI # num1 \- num2
'
Select frames \fInum1\fR through \fInum2\fR.
'
.TP 13
.BI # num1 \-
'
Select frames \fInum1\fR through the last frame.
'
.TP 13
.BI # name
'
Select the frame named \fIname\fR.
.PD
.PP
For example,
.Es
\fBgifsicle\fR happy.gif
.Ee
will use all of `happy.gif's frames, while
.Es
\fBgifsicle\fR happy.gif '#0'
.Ee
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.)
.PP
What
.B gifsicle
does 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.
'
.\" -----------------------------------------------------------------
.SS Frame Change Options

Frame change options insert new frames into an animation or replace or
delete frames that already exist. Some things\*Efor example, changing one
frame in an animation\*Eare difficult to express with frame selection, but
easy with frame changes.
'
.TP 5
.OA \-\-delete frames " [" frames ".\|.\|.]"
'
Delete
.I frames
from the input GIF.
'
.TP
.OA \-\-insert\-before "frame other-GIFs"
'
Insert
.I other-GIFs
before
.I frame
in the input GIF.
'
.TP
.OA \-\-append "other-GIFs"
'
Append
.I other-GIFs
to the input GIF.
'
.TP
.OA \-\-replace "frames other-GIFs"
'
Replace
.I frames
from the input GIF with
.IR other-GIFs .
'
.TP
\fB\-\-done\fR
'
Complete the current set of frame changes.
'
.PP
The
.I frames
arguments are frame selections (see above). These arguments always refer to
frames from the
.I original
input GIF. So, if `a.gif' has 3 frames and `b.gif' has one, this
command
.Es
\fBgifsicle\fR a.gif \fB\-\-delete\fR '#0' \fB\-\-replace\fR '#2' b.gif
.Ee
will produce an output animation with 2 frames: `a.gif' frame 1, then
`b.gif'.
.PP
The
.I 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
.I 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':
.Es
\fBgifsicle\fR \-b in.gif \fB\-\-replace\fR '#0' a.gif b.gif
.Ee
This command, however, replaces the first frame of `in.gif' with
`a.gif' and then processes `b.gif' separately:
.Es
\fBgifsicle\fR \-b in.gif \fB\-\-replace\fR '#0' a.gif \fB\-\-done\fR b.gif
.Ee
Warning: You shouldn't use both frame selections and frame changes on
the same input GIF.
'
.\" -----------------------------------------------------------------
.SS Image Options

Image options modify input images (by changing their interlacing,
transparency, and cropping, for example). Each image option stays in effect
until the next image option in the same category. They have three forms:
.QO \-\-X ,
.QO \-\-no\-X ,
and
.QO \-\-same\-X .
The default is
.QO \-\-same\-X ,
which means that \fBX\fR's value is copied from each input. The
converse,
.QO \-\-no\-X ,
erases \fBX\fR; for instance,
.OP \-\-no\-interlace
turns interlacing off, while
.OP \-\-no\-comments
strips comments. Only the
.QO \-\-X
form is generally described.
'
.Sp
.PD 0
.TP 5
.OA \-B color
.TP
.OA \-\-background color
'
Set the output GIF's background to
.IR color .
The argument can have the same forms as in the
.OP \-\-transparent
option below.
'
.Sp
.TP
.OA \-\-crop x1 , y1 - x2\fR,\fIy2
.TP
.OA \-\-crop x1 , y1 + width\fRx\fIheight
'
Crop the following frames to a smaller rectangular area. The top-left
corner of this rectangle is
.RI ( x1 , y1 );
you can give either the lower-right corner,
.RI ( x2 , y2 ),
or the width and height of the rectangle. If
.IR width " or " height
is negative, 
.B gifsicle
will make the image's width or height smaller by that amount. For example,
.OP \-\-crop " 2,2+-4x-4"
will shave 2 pixels off each side of the image.
'
.Sp
.TP
.OP \-\-flip\-horizontal
.TP
.OP \-\-flip\-vertical
'
Flip the following frames horizontally or vertically.
'
.Sp
.TP
.OP \-i
.TP
.OP \-\-interlace
'
Turn interlacing on.
'
.Sp
.TP
.OA \-S width x height
.TP
.OA \-\-logical\-screen width x height
'
Set the output logical screen to
.IR width x height .
.OP \-\-no\-logical\-screen
sets the output logical screen to the size of the largest output
frame, while
.OP \-\-same\-logical\-screen
sets the output logical screen to the largest input logical screen.
.OP \-\-screen
is a synonym for
.OP \-\-logical\-screen .
'
.Sp
.TP
.OA \-p x\fR,\fIy
.TP
.OA \-\-position x\fR,\fIy
'
Set the following frames' positions to 
.RI ( x , y ).
.OP \-\-no\-position
means
.OP \-\-position " 0,0."
Normally,
.OA \-\-position x\fR,\fIy
places every succeeding frame exactly at \fIx\fR,\fIy\fR. However, if an
entire animation is input, \fIx\fR,\fIy\fR is treated as the position for
the animation.
'
.Sp
.TP
.OP \-\-rotate\-90
.TP
.OP \-\-rotate\-180
.TP
.OP \-\-rotate\-270
'
Rotate the following frames by 90, 180, or 270 degrees.
.OP \-\-no\-rotate
turns off any rotation.
'
.Sp
.TP
.OA \-t color
.TP
.OA \-\-transparent color
'
Make
.I color
transparent in the following frames.
.I 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).
.PD
'
.\" -----------------------------------------------------------------
.SS Extension Options

Extension options add non-visual information to the output GIF. This
includes names, comments, and generic extensions.
'
.Sp
.PD 0
.TP 5
.OA \-x app\-name " " extension
.TP
.OA \-\-app\-extension app\-name " " extension
'
Add an application extension named
.I app\-name
and with the value
.I extension
to the output GIF.
'
.Sp
.TP
.OA \-c text
.TP
.OA \-\-comment text
'
Add a comment,
.IR text ,
to the output GIF. The comment will be placed before the next frame in
the stream.
.Sp
.OP \-\-no\-comments
and
.OP \-\-same\-comments
affect all the images following, and apply only to input GIF comments,
not ones added with
.OP \-\-comment .
'
.Sp
.TP
.OA \-\-extension number " " extension
'
Add an extension numbered
.I number
and with the value
.I extension
to the output GIF.
.I Number
can be in decimal, octal, hex, or it can be a single character like `n',
whose ASCII value is used.
.Sp
.OP \-\-no\-extensions
(or
.OP +x )
and
.OP \-\-same\-extensions
affect all the images following, and apply only to input GIF extensions.
'
.Sp
.TP
.OA \-n text
.TP
.OA \-\-name text
'
Set the next frame's name to
.IR text .
This name is stored as an extension in the output GIF. 
.Sp
.OP \-\-no\-names
and
.OP \-\-same\-names
affect all the images following. They apply only to input GIF names,
not ones added with
.OP \-\-name .
'
.PD
'
.\" -----------------------------------------------------------------
.SS Animation Options

Animation options are image options applying only to GIF animations. Most
of them act like image options, and have the same three forms (see above).
'
.Sp
.PD 0
.TP 5
.OA \-d time
.TP
.OA \-\-delay time
'
Set the delay between frames to
.IR time 
in hundredths of a second.
'
.Sp
.TP
.OA \-D method
.TP
.OA \-\-disposal method
'
Set the disposal method for the following frames to
.IR method .
.I Method
can be a number between 0 and 7 (although only 0 through 3 are
generally meaningful), or one of these names:
.BR none ","
.BR asis ","
.BR background " (or " bg "),"
.BR previous "."
.OP \-\-no\-disposal
means
.OP \-\-disposal = none .
'
.Sp
.TP
.OP \-l "[\fIcount\fR]"
.TP
.OP \-\-loopcount "[=\fIcount\fR]"
'
Set the Netscape loop extension to
.IR count .
.I Count
is an integer, or
.B forever
to loop endlessly. The default is
.BR forever .
.OP \-\-no\-loopcount
turns off looping.
'
.Sp
.TP
.OP \-O "[\fIlevel\fR]"
.TP
.OP \-\-optimize "[=\fIlevel\fR]"
'
Optimize output GIF animations for space.
.I Level
determines how much optimization is done. There are currently two
levels:
.Sp
.RS
.TP 5
.OP \-O1
Stores only the changed portion of each image. This is the default.
.TP 5
.OP \-O2
Also uses transparency to shrink the file further.
.Sp
.PP
There is no
.OP \-\-same\-optimize
option.
.RE
'
.Sp
.TP 5
.OA \-U
.TP
.OA \-\-unoptimize
'
Unoptimize GIF animations into an easy-to-edit form.
.Sp
GIF animations are often optimized (see 
.OP \-\-optimize )
to make them smaller and faster to load, which unfortunately makes them
difficult to edit.
.OP \-\-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.
.Sp
There is no
.OP \-\-same\-unoptimize
option.
.RE
'
.PD
'
.\" -----------------------------------------------------------------
.SS Whole-GIF Options

Whole-GIF options effect entire GIFs as they are read or written. They can
be turned off with
.QO \-\-no\-option .
.Sp
.PD 0
.TP 5
.OP \-\-careful
'
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
.OP \-\-careful
option if you are having problems with a particular image.
'
.Sp
.PD 0
.TP 5
.OA \-\-change\-color color1 " " color2
'
Change
.I color1
to
.I color2
in the following input GIFs. (The 
.I color
arguments have the same forms as in the
.OP \-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
.QA \-\-change\-color "color1 color2" \-\-change\-color "color2 color1" .
They all take effect as an input GIF is read.
.OP \-\-no\-change\-color
cancels all color changes.
'
.Sp
.TP
.OA \-k num
.TP
.OA \-\-colors num
'
Reduce the number of distinct colors in each output GIF to
.I num
or less.
.I Num 
must be between 2 and 256. This can be used to shrink output GIFs or
eliminate any local color tables.
.Sp
Unless you give
.OP \-\-use\-colormap ,
an adaptive group of colors is chosen from the existing color table.
You can affect this process with the
.OP \-\-color\-method
option. Gifsicle may need to add an additional color (making
.IR num +1
in all) if there is transparency in the image.
'
.Sp
.TP
.OA \-\-color\-method method
'
Determine how a smaller colormap is chosen. There are three choices:
.BR diversity ,
the default, is
.BR xv (1)'s
diversity algorithm, which uses a strict subset of the existing colors.
.B blend\-diversity
is a modification of this: some color values are blended from a group of
the existing colors.
.B median\-cut
is the median cut algorithm described by Heckbert.
.OP \-\-method
is a synonym for
.OP \-\-color\-method .
'
.Sp
.TP
.OA \-f
.TP
.OA \-\-dither
'
This option only matters if the colormap was changed. With
.OP \-\-dither
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.
'
.Sp
.TP
.OA \-\-resize width x height
'
Resize the output GIF to
.IR width x height .
Either
.I width
or
.I height
may be an underscore `_'. If the argument is
.IR width x_,
then the output GIF is scaled to
.I width
pixels wide without changing its aspect ratio. An analogous operation is
performed for
.RI _x height .
Resizing happens after all input frames have been combined and before
optimization.
'
.Sp
.TP
.OA \-\-resize\-width width
'
Same as
.OA \-\-resize width x_.
'
.Sp
.TP
.OA \-\-resize\-height height
'
Same as
.OA \-\-resize "" _x height .
'
.Sp
.TP
.OA \-\-scale Xfactor [x Yfactor ]
'
Scale the output GIF's width and height by
.IR Xfactor " and " Yfactor .
If
.I Yfactor
is not given, it defaults to
.IR Xfactor .
Scaling happens after all input frames have been combined and before
optimization.
'
.Sp
.TP
.OA \-\-transform\-colormap command
'
.I 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
.OP \-\-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.
'
.Sp
.TP
.OA \-\-use\-colormap colormap
'
Set the image's colormap to 
.IR colormap .
.I Colormap
can be
.BR web
for the 216-color ``Web-safe palette'';
.BR gray
for grayscale;
.BR 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
.OP \-\-colors\fR=\fIN
is also given, an
.IR N \-sized
subset of
.I colormap
will be used.
.Sp
Text colormap files have a very simple format:
.Es
# 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
.Ee
'
.PD
'
.SH EXAMPLES

Here are a bunch of examples showing how
.B gifsicle
is commonly used.
.PP
First, let's create an animation, `anim.gif':
.Es
% \fBgifsicle a.gif b.gif c.gif d.gif > anim.gif
.Ee
This animation will move very quickly: since we didn't specify a delay, 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
.OP \-\-delay
option.
.Es
% \fBgifsicle \-\-delay 50 a.gif b.gif c.gif d.gif > anim.gif
.Ee
If we also want the GIF to loop three times, we can use
.OP \-\-loopcount :
.Es
% \fBgifsicle \-d 50 \-\-loop=3 a.gif b.gif c.gif d.gif > anim.gif
.Ee
(Rather than type
.OP \-\-delay
again, we used its short form,
.OP \-d .
Many options have short forms; you can see them by running
.RB ` "gifsicle \-\-help" '.
We also abbreviated
.OP \-\-loopcount
to
.OP \-\-loop ,
which is OK since no other option starts with `loop'.)
.PP
To explode `anim.gif' into its component frames:
.Es
% \fBgifsicle \-\-explode anim.gif\fR
.br
% \fBls anim.gif*\fR
.br
anim.gif      anim.gif.000  anim.gif.001  anim.gif.002  anim.gif.003
.Ee
To optimize `anim.gif':
.Es
% \fBgifsicle \-b \-O2 anim.gif
.Ee
To change the second frame of `anim.gif' to `x.gif':
.Es
% \fBgifsicle \-b \-\-unoptimize \-O2 anim.gif \-\-replace '#1' x.gif
.Ee
.OP \-\-unoptimize
is used since `anim.gif' was optimized in the last step. Editing
individual frames in optimized GIFs is dangerous without
.OP \-\-unoptimize ;
frames following the changed frame could be corrupted by the change.
Of course, this might be what you want.
.PP
Note that
.OP \-\-unoptimize
and
.OP \-\-optimize
can be on simultaneously.
.OP \-\-unoptimize
affects
.I input
GIF files, while
.OP \-\-optimize
affects
.I output
GIF files.
.PP
To print information about the first and fourth frames of `anim.gif':
.Es
% \fBgifsicle \-I '#0' '#3' < anim.gif\fR
.br
(information printed)
.Ee
To make black the transparent color in all the GIFs in the current
directory, and also print information about each:
.Es
% \fBgifsicle \-bII \-\-trans '#000000' *.gif\fR
.br
(information printed)
.Ee
Giving
.OP \-I
twice forces normal output to occur. With only one
.OP \-I ,
the GIFs would not have changed on disk.
.PP
To change `anim.gif' to use a 64-color subset of the Web-safe palette:
.Es
% \fBgifsicle \-b \-\-colors=64 \-\-use\-col=web anim.gif\fR
.Ee
To make a dithered black-and-white version of `anim.gif':
.Es
% \fBgifsicle \-\-dither \-\-use\-col=bw anim.gif > anim-bw.gif\fR
.Ee
'
.SH BUGS
'
Some optimized output GIFs may appear incorrectly on some GIF
implementations (for example, Java's); see the
.OP \-\-careful
option.
.PP
Please email suggestions, additions, patches and bugs to
eddietwo@lcs.mit.edu.
'
.SH AUTHORS
.na
Eddie Kohler <eddietwo@lcs.mit.edu>
.br
http://www.pdos.lcs.mit.edu/~eddietwo/
.br
He wrote it.
.PP
Anne Dudfield <annied@frii.com>
.br
http://www.frii.com/~annied/
.br
She named it.
.PP
Hans Dinsen-Hansen <dino@danbbs.dk>
.br
http://www.danbbs.dk/~dino/
.br
Adaptive tree method for GIF writing.
.PP
http://www.lcdf.org/~eddietwo/gifsicle/
.br
The 
.B gifsicle
home page.
'