Research Of Resisting Geometric Attacks Image Watermarking Based On Object

With the rapid development of multimedia and Internet techniques, the multimedia security becomes an important and challenging research topic. Digital watermarking technique is an effective method for digital content protection such as copyright protection and becomes an important research area in the field of information hiding. Thus the research on digital watermarking is of great importance. For image watermarking, it is especially important to explore robust watermarking schemes that can resist geometric attacks; in addition, such kinds of schemes are also very difficult to design, because geometric distortions desynchronize the location and cause much difficulty in watermark detecting or extraction.The thesis carries on the systematical comparatively research of the digital watermarking algorithm which based on resisting geometric attacks. Firstly, the background and the actuality of digital watermarking is introduced, and the basic concept and character, generic model, typical algorithms, attack analysis and evaluation of performance of digital watermarking techniques are dissertated. Then focusing on watermarking of the resisting geometric attacks, some classical watermarking algorithms are presented, and their individual application environments, the advantages and the disadvantages are analyzed.Enlightened by the second generation watermarking and the research existence of watermarking algorithms, we propose a geometric-attacks-resist watermarking algorithm on object in the image based on affine transform. The thesis mainly carries on three aspects work of the following:1,Not embedding the watermark in the whole image but in a certain key object of the image. So the cropping action has no effect on the watermark extraction if the object in image is not cut.2,Combining the image watermarking techniques with image processing methods. Detecting the border by the effective edge detection process, and embedding the watermark in the central part of object by the border tracing method, we can lower the impact of the embedding watermark on the object edge detection.3,Embedding the watermark in the centroid symmetrical way, the watermark has the lower impact on coefficients of the affine transform, and it improve the robustness of resisting geometric attacks of the former affine transform algorithm. Plentiful emulation experiments prove that the proposed algorithm has the watermark's imperceptibility and robustness of resisting geometric attacks such as translation, scale, rotation, cropping, compression etc. Finally, we review the entire work, and make the expectation of the direction for the future research of watermarking.