Comments on "A Semi-blind Digital Watermarking Scheme Based on Singular Value Decomposition"

For original paper see J. Shich, D.Lou and M. Chang, ibid., vol.28, p.428-440, (2006). In a recent paper, a robust water-marking approach for hiding grayscale image watermark into digital images based on SVD (singular value decomposition) is proposed by Shich et al. This comment demonstrates that the high robustness of the proposed scheme against various attacks is a result of improper algorithm design. The extracted watermark is just determined by the reference watermark used during the extraction process no matter what the input suspected image is.