Graphics Interchange Format (.gif) defined in
RFC 2045 and
RFC 2046. This is the proprietary format for an 8-bit-per-pixel bitmap lossless image format introduced by CompuServe. The format uses a color palette of up to 256 distinct colors from the 24-bit-RGB color space. This limitation makes the GIF format unsuitable for reproducing color photographs and other images with continuous color. It is well-suited for logos and other graphics with solid areas of color.
For more details see the Wikipedia article:
Graphics Interchange Format
For the digital library, convert GIF images to PDF for the image version and upload the original GIF as the archive version.