I'm afraid that I don't know of any way to make an image of latitude, other than to manually calculate latitude for every pixel in the image. If this images are in the Geographic Lat/Long coordinate system, this would be pretty simple, based on the lat/long of the upper left corner, and the size of the pixels in degrees. But if it's in any other projection, it would be a lot trickier to figure out what the lat/long for each pixel are. You could reproject the image into Lat/Long (Map > Convert Map Projection), then write some IDL code to calculate latitude for each pixel, starting from the known latitude of the upper left corner and incrementing based on the size of the pixels in degrees. I hope that makes sense. Good luck. Peg