Google Groups: View Thread: "Since Mars is a popular topic these days, you might be interested in the methods NASA used to perform image compression. Here are reports about the panoramic imager:

http://europa.la.asu.edu:8585/PGG/greeley/courses/pdf/bell_2003.pdf
http://www.lpi.usra.edu/meetings/sixthmars2003/pdf/3029.pdf
Quote: 'Pancam relies heavily on use of the JPL ICER and LOCO compression algorithms to maximize data return within stringent mission downlink limits. All calibration and flight data products will be generated,archived, and released with the NASA Planetary Data System in PDS image format.'
This is a brief HTML description of the LOCO-based method they used for lossless compression:"
- posted by Sophont @ Saturday, January 17, 2004