Using dual watermarks to protect copyright of images

This paper presents a copyright protection scheme for images using dual watermarks (public and secret watermarks). The public watermark is a copyright symbol that contains the information about the owner, and the secret watermark is a fusion image that reflects both the characteristics of an original image and the public watermark. The secret watermark is embedded in the middle-frequency parts of the image feature blocks. The detector can give a judgment that if the suspicious image contains the given watermark or not. A reasonable protocol based on this scheme is also proposed. The owner can register his image to a trusted authority, and validate the copyright of a suspicious image. Experimental results demonstrate that this scheme can get good perceptual invisibility and adaptability. It is also robust against many attacks.