So I'm watching PBS at 3:00 AM and NOVA does a story on this

digital forensic guy who is developing software to detect manipulated digital photos. You think it would boil down to pixels and such but 2/3s of what his software does is look for lighting anomalies. There is one application that looks for duplicate pixel patterns but the others look for variances in lighting angles on different parts of the image.

Gee, that's what I was taught back in the '70s. If you're gonna fake something you have to match the size, perspective and lighting. Duh! 'Course the software is a bit more discerning than mere eyesight and it's able to detect only a few degrees of difference in light direction.

The last breakthrough they talked about was looking into the eyes of people in the image and seeing the reflections of light sources there to determine if they were all shot at the same time or if the image is a montage. Again, DUH! I could do that with a magnifying glass.

But hey, he's got the contract with Adobe, not me . . .