Current Version: 4.1.0
Uploaded: 19th January 1999

Libungif, a library for using uncompressed GIFs.

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Unfortunately, in that time there was an entity known as Unisys which saw that the GIF image format used a bit of knowledge known as LZW compression which belonged to them. Eager to advance their rights, they let it be known that they would not have use of their knowledge be infringed. All those who used or distributed software with LZW (and therefore GIF) compression algorithms must apply for licenses or cease forthwith.

Many programmers did cease their efforts with GIF. Questing for a new image to succeed the old, they created the PNG image format, a superior format capable of many things that GIF could never do. However, the legacy of GIF remained; many images remained in that format, still needing to be read and written and converted. Some software remained that could make only gibberish of PNG and yet resorted to GIFs for their graphic needs.

So it came to pass that libungif was born, a library which could be called in the same manner as giflib, but created uncompressed gifs instead of ones encoded with LZW. This allowed programmers to write software that was capable of talking to either giflib or libungif during the transition from gif to png.

3rd February 2000
cvs servers set up for both giflib and libungif. Bugs and patches I've received are in the libungif repository in the backlog subdirectory. Download instructions on the Libungif availability page.

5th December 1999
I've fixed the ftp server on prtr-13. You should now be able to use anonymous ftp and see the files that reside there.

The 4.x series should remain API compatible with giflib-3.0, but is no longer binary compatible. Your programs should continue to compile without changes, but must be compiled against the new library in order to run correctly. Additionally, if your program uses gif extensions, I would highly recommend you look at the deprecations and additions made in the Extension structures.

If a 5.x series should ever make it to the light of day, it will contain API changes to cleanup the code.

The GIF Controversy: A Software Developer's Perspective provides background information on Unisys's patent 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/

Some basic info about libungif can be found in other languages: French, German, Spanish.

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.