I have an image where each DN is 0. I want to change the DN values to unique numbers that increase by a unit of 1 according to the pixel location in the array. For example if I have an image where there are 2 rows, 2 colums, I want to go from 0000 1234 0000 to 5678. Only this image is much larger. Is there an easy way to do this in ENVI or IDL (before I write the code myself)? Thanks.