It wouldn't be too difficult to set up a batch program in ENVI that systematically created all possible band ratio combinations through a loop process, but depending on the number of bands in your input file, you could end up with a very large volume of output files to sort through. For example, AVIRIS has 224 bands and if the placement of bands in the numerator and denominator are important to you (e.g., Band 4 / Band 3 is different than Band 3 / Band 4), then the total number of possible output files would look like this: 224!/(224-2)! = 49952 That's almost 50,000 output files. The program would take a long time to run and you might encounter some hard drive storage issues--depending on your hardware setup and how big the input file is. I should mention that band ratio output files are normally stored in floating point, which generally takes up twice the space on a hard drive that a band of data from the input file would take up (normally unsigned integer). If numerator/denominator placement is not important to you, the the total number of output files would look like this: 224!/2!*(224-2)! = 24976 Half as many as before, but still a very large number. If you have less input bands than AVIRIS, and you start eliminating bands due to atmospheric aborption features, adjacency due to oversampling, and a priori knowledge, you might be able to get the number of output files down to a more reasonable level.