I have found many discussions online regarding pixel aspect ratio, but none addressing my problem. No matter what I do to my grayscale scan, adjustments don't stick. Levels, curves, brightness/contrast - when I darken the image and hit OK, it doesn't stay dark, it goes back to the original. I KNOW this is related to how the image scanned, but I don't know how to fix it. It scans at 600 dpi on a copier, I don't have many options.