RST invariant digital image watermarking based on a new phase-only filtering method

This paper presents a new rotation, scaling and translation invariant digital image watermarking scheme based on log-polar mapping and phase-only filtering method. The watermark is embedded in spatial domain imperceptibly. The log-polar mapping and the phase-only filtering method are used to generate resistance to common geometric attacks such as rotation, scaling, and translation. Experiments show that the proposed scheme is robust against various attacks including geometric attacks. The method of inverting RST transformations can be used in other watermarking algorithms.