I'm looking for a simple way to average multiple images that have different missing data in each image. I've tried SUM DATA BANDS, as well as Band Math, but i still run into the same problem. With SUM DATA BANDS, i can't exclude missing data. With Band Math i was able to add all the data i wanted but then i couldn't average it correctly. Missing data has a value of either 254 or 255, so i wrote: (B1 LT 250) *B1 + (B2 LT 250) *B2...... for 8 bands. However, when i divide the whole thing by 8 at the end, i end up dividing all pixel data by 8, even if they might not contain a sum of all 8. This corrupts all pixels that didn't have data available from all 8 images. Instead i want it to average whatever is available at each pixel, anywhere from 1-8 images. Anyone have any experience with this? I'm running ENVI 4.1 on windows. thanks