Identifying and prefiltering images

Given the ability of photorealistic computer graphics (photorealistic CG) to emulate photographic images, as seen in movies and the print media today, there is little doubt that uninformed viewers can easily mistake photorealistic computer- generated graphics for photographic images. In fact, there was already evidence 20 years ago that to the naked eye certain computer graphics were visually indistinguishable from photographic images. Such convincing photorealism qualifies computer graphics as a form of image forgery that can be unscrupulously exploited. Some popular Web sites even highlight examples of computer generated photorealism that human eyes find indistinguishable from photographic images.