I think I want this software (when it comes out).

From Photoshopped or Not? A Tool to Tell:

Dr. Farid and Eric Kee, a Ph.D. student in computer science at Dartmouth, are proposing a software tool for measuring how much fashion and beauty photos have been altered, a 1-to-5 scale that distinguishes the infinitesimal from the fantastic. Their research is being published this week in a scholarly journal, The Proceedings of the National Academy of Sciences.

The algorithm developed by Dr. Farid and Mr. Kee statistically measures how much the image of a person’s face and body has been altered. Many of the before-and-after photos for their research were plucked from the Web sites of professional photo retouchers, promoting their skills.

The algorithm is meant to mimic human perceptions. To do that, hundreds of people were recruited online to compare sets of before-and-after images and to determine the 1-to-5 scale, from minimally altered to starkly changed. The human rankings were used to train the software.

I think it would be useful if this software were simply available in the cloud, like TinEye or Google Reverse Image search. And the rating could simply show up next to image results from searches.