Current version: 4.1.0
Uploaded: 9th February, 1999

GifLib, a library for manipulating gif images

Notice: I am going on a long backpacking vacation between March and September 1999. Please refer to the links section for a site that will be coordinating patches and fixes during this time.

Note: due to Unisys's increasingly aggressive interpretation of its patent claims on the LZW compression format, I can no longer recommend the use of the GIFLIB library or utilities. GIFLIB may be withdrawn in the near future.

For extended discussion of the situation, see The GIF Controversy: A Software Developer's Perspective. Essentially, since 1996 Unisys no longer exempts even `freeware' from its licensing requirements. If you use this library in any way and Unisys decides it doesn't like you, you could be open to lawsuit.

If you are using giflib because you need an image format for use in your program, but do not necessarily need that format to be gif, I suggest you consider switching over to PNG. PNG (Portable Network Graphic) is the successor format to gif and is both unencumbered by LZW compression (it generally achieves better compression of image data than gifs) and designed to do many things that gif can not (24-bit true-colour, alpha channel support, etc.) Additionally, there is a free, stable, open-source c reference library that you can start using immediately. See the PNG Home Page for more details and download instructions.

If, on the other hand, your need is specifically to access gif files, you might want to consider the libungif library. This library does not use LZW to encode the gifs it outputs. Patent lawyers seem to agree that the wording of the Unisys patent is such that code which does decoding only (and not encoding) is not covered by the patent, so you may be safe using this library. [Note: Unisys has at times expressed views which seem to disagree with this interpretation. If you're concerned, speak to a lawyer yourself.] This library uses the same API as giflib and should be available in a binary compatible version.

If you still have your heart set on using giflib, the latest version should be available from: http://sourceforge.net/projects/libungif.

Features and bugfixes that have not yet entered the main distribution may be available at: http://www.arrakeen.demon.co.uk/giflib/

Important Links

The GIF Controversy: A Software Developer's Perspective provides background information on Unisys's patent claim and how their licensing claims have changed over time.

Michael Brown, michael_brown_uk@hotmail.com, has started a patches page that has bug fixes and enhancements that are not yet available in the main giflib/libungif tree. Check it out here: http://www.arrakeen.demon.co.uk/giflib/

Bug Reports

Please send bug reports to libungif@prtr-13.ucsc.edu. Please include what architecture you are running on, whether you compiled the library yourself or are using a precompiled binary, the version of the library, what command you use to create the error, and anything else that you think is relevant to the problem.