RST-invariant Digital Watermarking based on Template and Log-polar Mapping

X. Qi (USA)


Digital watermarking, log-polar mapping, and template.


This paper proposes a rotation, scaling, and translation (RST) resistant watermarking over the template matching based method. A one-way hash function is utilized to generate the highly secure embedding positions in the mid-frequencies against position attacks. A spread spectrum watermark is embedded into these positions in the frequency domain based on the local perceptual capability. This spread embedded watermark ensures a large measure of security against unintentional or intentional attacks. Two structural template lines are then added in the polar coordinate system for detecting any combination of the geometrical distortions. The RST invariant property of the log-polar mapping (LPM) in the Fourier transformation domain is also utilized in our detection scheme to facilitate fast and robust template detection. The watermark is detected based on the correlation between the recovered and embedded watermarks. Our proposed RST-invariant watermarking approach demonstrates a better performance as compared with some peer systems in the literature. The experimental results also demonstrate the robustness of the method against some common image processing operations such as JPEG compression, enhancement, and any combination of the geometric distortion.

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