US Patent 7463389 Image processing method, image processing device and program

A copy-forgery-inhibited pattern image can be enlarged or reduced. More specifically, the shapes of a latent image portion and a background portion are changed according to a certain magnification factor, and a pattern appropriate for the copy-forgery-inhibited pattern image is applied to a dot pattern making up the latent image portion and a background portion. Thus, the appropriate copy-forgery-inhibited pattern image according to the size of a document image after change can be generated without deteriorating the function of the copy-forgery-inhibited pattern image, and the copy-forgery-inhibited pattern image can be overlaid with the document image and output.