Abstract: In this paper, a RST (Rotation, Scaling and Translation) invariant color image watermarking algorithm is proposed by using Quaternion Fourier-Mellin Transforms (QFMT). Firstly translation invariance is achieved by circular feature region which can be generated using invariant centroid. Then the circular region is transferred into QFMT domain. Rotation invariance and scaling invariance are constructed by embedding the digital watermarking into the QFMT spread spectrum. The proposed color image watermarking scheme is of better robustness against RST attacks. And the proposed algorithm spreads the image distortions from the watermarking into the three channels of host image, thus leading to an increased capacity of watermarking embedding. Experimental results demonstrate that this method is of good robustness against JPEG compression and RST attacks.
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Key words: image watermarking, quaternion Fourier-Mellin transforms, color image, RST attacks, quaternion Fourier transforms, rubustness