Research On Digital Watermarking For Digital Right Management

With the rapid development of computer networks and multimedia technology, digital multimedia products are becoming increasingly popular and extensively applicable, which are so easy to be edited, copied and transmitted that they have facilitated the share of information and boosted the progress of today's society. However, on the other hand, some problems concerned with Digital Right Management (DRM) and content authentication are becoming more and more striking, which is a urgent problem for solving in the digital world. The digital watermarking technology as an essential technical method solving DRM and content authentication has already started to draw wide attention of many scholars in this field all over the world. The research on digital watermarking technology can be divided into two aspects approximately. One is the digital watermark algorithm study. The other is about how to apply the digital watermark algorithm to the DRM, namely application protocol study, and they are researched deeply in the dissertation. Main achievements are summarized as follows:(1) This thesis proposed a wavelet tree-quantization readable watermarking algorithm based on chaotic mapping and human visual system. In the algorithm, the watermark is a meaningful binary bitmap and is modulated by a chaotic sequence before embedding. By analyzing the tree structure relation of wavelet coefficients and the model of human visual system, each watermark bit is embedded using two wavelet trees of host image, The trees are so quantized that they exhibit a large enough statistical difference which will later be used for watermark extraction and the watermarking detection needs no host image and original watermark. Experiment results show the watermarking is invisible, and robust to several kinds of attack.(2) The watermark resisting to geometric distortion is a very difficult and challenging subject. To solve this problem, two method are proposed.One method, which estimates rotation and scaling based on template embedding, has low computing complexity for template matching.One method which estimates translation based on invariant centriod has solve the translation synchronization of the original watermarking images and test images in the wavelet domain watermark. In the experiments, we applied the two methods to the proposed watermarking algorithm, and compared the algorithm with two typical watermarking algorithms resisting to geometric distortion, the results of experiments show it has higher performance in resisting to geometric distortion and JPEG2000 compression.(3) On the basis of analyzing the obligations and requirements for the authors, the sellers, the buyers and the copyright centers in the system of DRM, we have produced a protocol to protect the rights and interests of each participator in the digital media transaction process. The protocol takes into account the usage legality, integrity, and communication security for digital works and also protects the trading fairness at one time.