A new version of ISIS is available to download from the USGS here
The Integrated System for Imagers and Spectrometers (Isis) is a specialized image processing package. It has many standard image processing operations such as contrast stretch, image algebra, filters, and statistical analysis. Isis operates on both classical two-dimensional images as well as three-dimensional cubes collected from imaging spectrometers. The real power of Isis, however, is its unique capabilities for processing data from NASA spacecraft missions such as Voyager, Viking, Galileo, Mars Global Surveyor, and Mars Odyssey.