Research On New Methods Of Digital Image Watermark

With the rapid development of computer science, the digital product market has got a highly boom, and a great number of information security problems as well. It's very important to doing the technical research about copyright protection. Digital watermark is a kind of technique combined with signal processing, image processing, mode recognition etc. It has been one of the most popular techniques for copyright protection.Based on the analysis of existing digital watermark techniques, this paper introduces many new theories to digital watermark algothrims. The experiments have shown that those new theories really improved the robustness and ivisiblity of the watermark. The main contents are described as followed:(1) A blind watermarking algorithm based on the singular values decomposition for its favorable stability was proposed. This algorithm embeds a small disturbance watermarking in the image's singular values to achieve strong robustness and transparency, and introduces the FastICA algorithm to ensure fast astringency and blind extraction. The experiment shows that this algorithm has the strong robustness to general attacks. It can also resist the geometrical attack. It shows the unique superiority and great advantage.(2) A geometry attack resisted algorithm was proposed in contourlet domain. The watermark was embedded in the coefficients of contourlet transform. Before watermark extraction, the geometric attacked image can be reverted to its original shape by geometric moments which were caculated just after the watermark was embedded. The experiment results showed that this algorithm can resist all kinds of geometry attack, and also can resist many kinds of general attacks with a good quality of the extracted watermark. The embedding position can be located adaptively. This alogrithm is quite fit for the situation with highly requirement of resistence about geometry attack.(3) In order to improve the robustness and efficiency of the watermark algorithm,a robust watermark algorithm in contourlet domain based on Mean Shift texture clustering is proposed in this paper for the first time. This algorithm selects the energy, entropy, contrast for texture features, rapidly and accurately extracts strong regional texture of host images by the way of Mean Shift fast clustering algorithm, which make algorithm's the convergence rate being better than FCM clustering as well as K-means clustering. This algorithm embedded watermark into the big coefficients in contourlet domain of image strong texture area, through texture clustering outcome adaptively controls the watermark embedding locations and strength, which directly brings the more covert and strong robustness. The experiment shows that this algorithm can be very good to meet the requirements of rapid clustering, and adaptively selects the precise watermark embedding position and embedding strength. This algorithm has the strong robustness to regular attacks. This algorithm has realized the blind detection.