Software to detect photo manipulation?

Question

How can a lay user search for possibly manipulated areas in a photography? Is there software which assists you in this? Or a tutorial at least?

Answer 1

http://news.cnet.com/Smoking-out-photo-hoaxes-with-software/2100-1008_3-6033312.html

Answer 2

This is really a high art. I strongly doubt there is any software capable of determining whether a photograph was manipulated or not - any software available in the field will require extensive preparation, creating a 3D model in the photo to determine the position of the light source(s), measure whether the shadow angles are correct, and so on and so on. I'm quite sure there is no trivial solution. What do you need this for?

Answer 3

If this were possible within any degree of accuracy then lawyers would save billions of dollars on expert witness testimonies every year.

Answer 4

I heard a presentation by David G. Stork a while ago on finding out if renaissance paintings where actually drawn from a single, real model, or if the artist combined different sketches when making his final picture (e.g. drawing a background and adding a picture of a sitter in front of it later --- somehow analogous to a photo manipulation).

The bottom line of his talk was, yes, it is possible and even with pretty high accuracy, but you need to make 3D models of the scenes (not sure how much computer programs can assist with that), and the computations to fit the light models to the picture and find the discrepancies are pretty intense.

EDIT I just realized that this is what Vlad was pointing to.

Answer 5

There is ongoing research on the topic, check out http://www.hackerfactor.com/blog/index.php?/archives/322-Body-By-Victoria.html.

I do not know of readily available software though, especially not for lay users. I believe any software would still rely on some user's skilled interpretation.