Joint Bi-level Image Experts Group
JBIG is short for the 'Joint Bi-level Image experts Group'. This was (and is) a group of experts nominated by national standards bodies and major companies to work to produce standards for bi-level image coding. The 'joint' refers to its status as a committee working on both ISO and ITU-T standards. The 'official' title of the committee is ISO/IEC JTC1 SC29 Working Group 1, and is responsible for both JPEG and JBIG standards.
JBIG have developed IS 11544 (ITU-T T.82) for the lossless compression of a bi-level image. It can also be used for coding greyscale and colour images with limited numbers of bits per pixel. It can be seen as a form of facsimile encoding, similar to Group 3 or Group 4 fax, offering between 20 and 80% improvement in compression over these methods (about 20 to one over the original uncompressed digital bit map).