Quadruple Watermarking against Geometrical Attacks Based on Searching for Vertexes

Hai-Yan ZHAO  Hong-Xia WANG  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E90-A   No.6   pp.1244-1247
Publication Date: 2007/06/01
Online ISSN: 1745-1337
DOI: 10.1093/ietfec/e90-a.6.1244
Print ISSN: 0916-8508
Type of Manuscript: LETTER
Category: Information Security
quadruple watermarking,  geometrical attacks,  robustness,  synchronization,  blind,  

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A new quadruple watermarking scheme of digital images against geometrical attacks is proposed in this letter. We treat the center and the four vertexes of the original image as the reference points and embed the same quadruple watermarks by means of polar coordinates, which is geometrically invariant. The center of an image is assumed to not to be removed after rotating, scaling and local distortions according to the general practical image processing. In the watermark extraction process, the vertexes of the image are found by a searching method. Thus watermark synchronization is obtained. Experimental results show that the scheme is robust to the geometrical distortions including rotation, scaling, cropping and local distortions.