Patent ID: 8452044

Claim:
An image processing apparatus, comprising: a latent image generation device that generates electronic image data of a line latent image, the line latent image becoming visible when a line filter provided with a line pattern formed on a transparent film is superimposed thereon; a digital watermark generation device that generates electronic image data of digital watermarks to set an embedding intensity of the digital watermarks so that an upper limit and a lower limit of the embedding intensity of the digital watermarks are set so that the number of detections of the digital watermarks embedded in the printed matter is not less than a predetermined number, and a difference between the number of detections of the digital watermarks in an original and the number of detections of the digital watermarks in a copy of the printed matter is not less than a predetermined value; and an image merging device that merges, in a predetermined region, electronic image data of the line latent image generated by the latent image generation device with the electronic image data generated by the digital watermarks to generate merged electronic image data such that a superimposed area between the line latent images and the digital watermarks is smaller than a predetermined value and the increment of an area in which the line latent images and the digital watermarks are printed with respect to the area in which the line latent images are printed is less than a predetermined ratio.