Watermarking algorithm for digital image against RST attacks based on geometric moment

Resistance to rotation, scaling, translation (RST) attacks is a difficulty of digital watermarks. A novel watermark algorithm which is resistant to geometric attacks based on geometric moment was proposed. Geometric distortions of the watermarked image were estimated accurately and its inverse transformation was corrected by geometric moments, of the original and the watermarked images, used for pattern recognition, to ensure synchronization between embedding and detecting of the watermark and improve the resistance to RST attacks. The simulated results demonstrate that the algorithm is very robust to RST attacks.