GIFSICLE 1.21
=============

ABOUT GIFSICLE
--------------
   Gifsicle twaddles GIF image files in a variety of ways. It is better
than many of the freely available GIF twaddlers on the market -- for one
thing, it has more options.

   It supports merging several GIFs into a GIF animation; exploding an
animation into its component frames; changing individual frames in an
animation; turning interlacing on and off; adding transparency; adding
delays, disposals, and looping to animations; adding or removing comments;
flipping and rotation; optimizing animations for space; and changing
images' colormaps, among other things. Extensive command-line options
control which, if any, of these occur.

   Gifview, a companion program requiring X11, displays GIF images and
animations on an X display. It can display multi-frame GIFs either as
slideshows, displaying one frame at a time, or as real-time animations.

   Gifdiff, another companion program, checks two GIF files for identical
visual appearance. This is probably most useful for testing
GIF-manipulating software.

   Each of these programs has a manpage, `PROGRAMNAME.1'.

   The Gifsicle package comes with NO WARRANTY, express or implied,
including, but not limited to, the implied warranties of merchantability
and fitness for a particular purpose.

THE GIF PATENTS AND UNGIFS
--------------------------
   Unisys owns patents on the Lempel-Ziv-Welch compression algorithm used
in GIFs, which means that GIF-manipulating software cannot be truly free.
Some people in the know have said that decompression is not covered by the
LZW patents (I have my doubts). That leaves compression. Independently,
Toshio Kuratomi <badger@prtr-13.ucsc.edu> and Hutchison Avenue Software
Corporation (http://www.hasc.com/, <info@hasc.com>) cut the Gordian knot by
writing GIFs without LZW compression. These GIFs are larger, but perfectly
readable by normal GIF viewers, and they avoid the Unisys patents.

   Gifsicle can be configured to write run-length-encoded GIFs, rather than
LZW-compressed GIFs, making it completely free software (if you believe
that decompression isn't patented). Turn this on by giving `./configure'
the `--enable-ungif' switch. The disadvantage: your GIF outputs will be
larger, often by a factor of 2 or more. You can tell which gifsicle you are
running by typing `gifsicle --version'. If it says `(ungif)', gifsicle is
writing run-length-encoded GIFs.

   This gifsicle package may have been distributed without the file that
implements LZW compression. If you try to configure such a distribution
without `--enable-ungif', you will get an error message. See the Gifsicle
web page <http://www.lcdf.org/gifsicle/> if you have such a distribution
but want LZW compression.

MAKING GIFSICLE ON UNIX
-----------------------
   You need an ANSI C compiler, such as gcc.

   Just type `./configure', then `make'. `make install' will build and
install gifsicle and its manual page (under /usr/local by default).

   `./configure' accepts the usual options. See `INSTALL' for more
details.

   To build without gifview (for example, if you don't have X11), give the
`--disable-gifview' option. To build without gifdiff, give the
`--disable-gifdiff' option. To have Gifsicle create unGIFs instead of GIFs,
avoiding the Unisys patents, give the `--enable-ungif' option.

MAKING GIFSICLE ON 32-BIT WINDOWS
---------------------------------
   Emil Mikulic <darkmoon@connexus.net.au> has provided a Makefile for
building gifsicle out of the box on 32-bit Windows. It has since been
updated by Eddie Kohler and Steven Marthouse <comments@vrml3d.com>. Just
unpack the distribution, change into that directory, and type

	nmake -f Makefile.w32

Gifview will not be built. You will need to edit `Makefile.w32' if you are
building ungifsicle, or if you are not compiling with a Microsoft compiler.
You can edit it with any text editor (like Notepad). See the file for more
information.

CHANGES
-------
   See `NEWS' in this directory for a detailed listing of changes.

BUGS, SUGGESTIONS, ETC.
-----------------------
   Please write me if you have trouble building or running gifsicle, or if
you have suggestions or patches.

	Eddie Kohler
	eddietwo@lcs.mit.edu
	http://www.pdos.lcs.mit.edu/~eddietwo/

GIFSICLE HOME PAGE
------------------
   For latest distributions, bug reports, and other stuff, see the Gifsicle
home page at

	http://www.lcdf.org/gifsicle/

COPYRIGHT/LICENSE
-----------------
   All source code is Copyright (C) 1997-9 Eddie Kohler.

   IF YOU PLAN TO USE GIFSICLE ONLY TO CREATE OR MODIFY GIF IMAGES, DON'T
WORRY ABOUT THE REST OF THIS SECTION. Anyone can use Gifsicle however they
wish; the license applies only to those who plan to copy, distribute, or
alter its code. If you use Gifsicle for an organizational or commercial Web
site, I would appreciate a link to the Gifsicle home page on any `About
This Server' page, but it's not required.

   This code, with the exception of the GIF compression code in gifwrite.c,
is distributed under the GNU General Public License, Version 2, or, at your
discretion, any later version. The GNU General Public License is available
via the Web at <http://www.gnu.org/copyleft/gpl.html>

   The following alternative license may be used at your discretion.

   Permission is granted to copy, distribute, or alter gifsicle, whole
or in part, as long as source code copyright notices are kept intact, with
the following restrictions.

   1. Unisys Corp. holds a patent on the Lempel-Ziv-Welch compression
algorithm used by GIF images. When this first became an issue several years
ago, Unisys stated that programs available at no cost to the user, like
Gifsicle, could use LZW compression in the context of GIF images without
obtaining a license. If you plan to distribute GIF writing code in a
shareware or commercial product, you will need to worry about obtaining a
license. (Many people believe that LZW decompression is not covered by the
Unisys patent, so GIF reading code is probably all right.)

   2. Developers or distributors who plan to use Gifsicle code, whole or in
part, in a product whose source code will not be made available to the end
user -- more precisely, in a context which would violate the GPL -- MUST
contact the author and obtain permission before doing so.

AUTHORS
-------
Eddie Kohler <eddietwo@lcs.mit.edu>
http://www.pdos.lcs.mit.edu/~eddietwo/
He wrote it.

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

David Hedbor <david@hedbor.org>
Many bug reports and constructive whining about the optimizer.

Emil Mikulic <darkmoon@connexus.net.au>
Win32 port help.

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