In this paper, a method for digital image watermarking is described that is
resistant to geometric transformations. A private key, which allows a very
large number of watermarks, determines the watermark, which is embedded on
a ring in the DFT domain. The watermark possesses circular symmetry. Corre
lation is used for watermark detection. The original image is not required
in detection. The proposed method is resistant to JPEG compression, filteri
ng, noise addition, scaling, translation, cropping, rotation, printing and
rescanning. Experimental results prove the robustness of this method agains
t the aforementioned attacks.