1. A method for embedding information in an image so that the image will have different information when the image is reproduced by a scanning or printing process, the method comprising the steps of: embedding digital information in an image; printing the embedded digital information and the image to produce a original printed image; scanning the original printed image to obtain a digital image of the embedded information and the image; determining the signal strength of the original image; and comparing the signal strength of a printed image with the signal strength of the original printed image to determine whether or not the printed image is a copy of the original printed image.