A rectification method for RST invariant digital image watermarking
Based on the log-polar mapping (LPM) and phase-only filtering method, this paper proposes a rectification method that can be used by any image watermarking algorithm to provide robustness against rotation, scaling and translation (RST) transformation. We obtain the RST parameters by calculating the cross-correlation between a template and the magnitude of the image in the corresponding domains. We compare the filter performance by three criteria. The detection accuracy for rotation and scaling is also presented.