GIF

• Graphics Interchange Format
• Product of Compuserve Inc, 1987
• "A standard defining a mechanism for the storage and transmission of raster-based graphics information."
• 256 colors defined by a RGB color map.
• Supports several images in a file -> animation.
• Each image in a file can have its own local color map
• Interlazed or non-interlazed
• LZW (by Lempel-Ziv & Welch) compression - allows the image to be decompressed and displayed on the run. Variable-length codes are used to replace patterns detected in the original data. The algorithm uses a code or translation table constructed from the patterns encountered in the original data. Each new pattern is entered into the table and its index is used to replace it in the compressed stream.
• The position of individual pixels does not have to be indicated separately, since they are stored sequentially from top left to bottom right.
• Royalty is paid to IBM and Unisys for use of the LZW algorithm, therefor a replacement will come: Portable Network Graphics (PNG) by IETF.

Find out more about GIF on GIF Animation on the WWW which includes links to the GIF specifications.