The US patent covering the LZW compression algorithm used in GIF images.
Old page from the League for Programming Freedom (LPF) on the Unisys patent controversy.
A 2004 article on the GIF controversy seen from a software developer's perspective. Includes original interviews, a historical perspective, and a detailed bibliography.
Page prepared in 2003 about a program that converts files from GIF to PNG. The conversion preserves all graphic information, including transparency.
Original specification describing the file layout as originated by CompuServe. Also known as Gif87a.
Provides detailed specification of file layout, encoding and decoding algorithm, and color space model for gif89a.
Detailed information, specifications, and background of the Graphics Interchange Format.