(Error Level Analysis. The bright area indicates where the image has been manipulated)

Dr. Neal Krawetz presented a software tool that is able to detect if an image has been digitally processed using format- and image-analysing technics @ this years BlackHat Convention.

It is actually possible to determine the last "tool" that created the image ---> this means u can tell the camera model if its the original image or the version of photoshop that has been used to alter the image.

see his blog for more examples.

Pdf slides of Krawetz s presentation @ BlackHat (35mb / this document explains the basic techniques used & is not2geeky)

SourceCode

pOUt