Tuesday, June 15, 2010
One way to check and see if an image is authentic, or a composite, is to look at the macroblocks (compression component) in Channel mode. The macroblocks, or groups of pixels, should be the same size and orientation. One sure sign of a fake is if the blocks change in size from one part of the picture to another (cut/paste) or in both size and orientation (cut/paste/rotate).
You may need to check each channel to be able to see this effect as the compression macroblocks may be more apparent in one channel vs. the others. Remember, it's just not possible for an image editing program to compress one side of an image differently, or at a different angle than another.