Photographs can sometimes be altered or changed in order to create photographs which appear to be of a scene which never took place, or did not take place at the place and time when the photograph is purported to have been taken. One way of circumventing known systems to detect this sort of falsified image is to take a photograph of a printed altered image. The present invention is a method of detecting such “photographs of photographs” by comparing two photographs of the same seen taken at the same time, with different exposures.