| With the growth of network and multimedia technology, the copyright protection becomes more and more important. In this thesis, analyze the characteristic, classes and application area of the digital watermarking, and then introduce DWT digital watermark algorithm combines with the human visual system and the improved algorithm.The main idea of the use of wavelet transform in image processing is that signal is expressed on time field and scale domain,decomposition dimensions of domain being to should indifferent frequency range. The low frequency tape has kept the main information of the image and it decide the human apperceive degree,but the edge and the texture features of the image are general to concentrate in the high frequency tape, if we add the watermarking to the low frequency tape,it can lead to the reduce of the visual effect of image,if we add the watermark into the high frequency tapes then the information of the high frequency tape will be lost after general image processing,and the robustness of the digital watermarking will be reduced. Considering the above all,we should add the watermark into the intermediate frequency tapes,then the invisibility will be assured and the robustness of the algorithm will be enhanced.In order to make watermark image better resist to various attacks, the watermarking and the embedding algorithms in low and middle domains,associated with the human visual system , modulation of positive and negative and associative memory function of Hopfield network, are proposed.To increase the security of watermarking , convertion of Arnold is used in the algorithm. The result of the experiment indicates that the algorithm improved can balance the invisibility the steadiness and its capability,the algorithm can assure the robustness to familiar image process such as noise contamination,compression and cropping,it is a feasible algorithm and it make an active sense to the present wavelet digital watermarking algorithm. |
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