Busting PhotoCHOPs

Having done hundreds of photoCHOPS (using photoshop to manipulate photographs) myself, from easy chops such as manipulating contrast, brightness, and sharpness to complex chops such as modifying cars, it is hard for me to believe the authenticity of many digital images circulating around the Internet depicting unbelievable moments in life. Hell, with digital printing technology improving dramtically in the past few years, how can anyone fully trust a print photo these days? I am sure some of you may recall seeing the photo displayed on the top right here with a shark leaping out of the water attacking the man hanging from the helicopter. This was an easy chop, technically speaking. It can be done by extracting the shark, the bottom photo of a breaching shark photographed by the famous photographer Charles Maxwell, with water splashes around it and pasting it onto the middle image of the helicopter taken by Lance Cheung near the Golden Gate bridge to make the final composite image. Once the paste is done, you then have to match the colors, contrast, and brightness of the two and then do little touch ups around the edges of the shark extraction to make the pasted image blend in with the helicopter image. To the naked eye, it is almost impossible to tell the difference between reality or illusion especially if the image has been manipulated by an experienced photoshop user. In fact, something that has been manipulated may seem more real than the original photograph.
Professor Hany Farid and Dartmouth graduate students claim that they have developed a mathematical technique to detect mainpulated images. Dartmouth news writes, "Farid's algorithm looks for the evidence inevitably left behind after image tinkering. Statistical clues lurk in all digital images, and the ones that have been tampered with contain altered statistics." Although I doubt this will decrease the number of fakes circulating themselves as real photos, at least, we have better techniques to bust a photochop rather than arguing about it or trying to locate the originals as proof.

Read the Dartmouth Story Here

Picture from Shark Hoax Story by National Geographic.

Thanks to boingboing.net for the story and links.