Hi--I'm new to ENVI--using it in an archaeological context. Here's my question--I have some ROI's defined for a river delta. I also have a survey area that takes up a small part of the river delta--but since the survey area is unexplored, there are no ROI's from that area. I tried using an Endmember classification with some interesting results. The endmember spectra were just imported from the ROI's for the original image. But can I do this, or do I need to match the historgrams first? Will this happen automatically? A followup question--I'm having excellent visual results with the Gaussian stretch of an Aster 9-3-1 image. I've applied this stretch to the survey area. As above, if I want to use the ROI's from the other (full delta) image, do I need to match the histograms first? Thanks very much! --s