Research On Image Digital Watermark Technology

With the growth of network and multimedia technology, the copyright protection of multimedia becomes more and more important. Watermark technology, as a main method of providing copyright protection, has been widely studied and applied. In the paper, we mostly discuss the principle of digital watermark technology and algorithm, and the application of it in multimedia security. Finally, we address the possible direction of watermark technology for future research. The main research work and contributions of the dissertation are as follow:1 Digital Image WatermarkAn algorithm for meaningful watermark is proposed. Most digital watermark use pseudo random sequences as watermarks and so they only answer 'yes' or 'no' for detecting the watermark. In some application, embedding meaningful watermark is important. But there are many difficulties. In this paper, we propose an adaptive digital watermark algorithm. Mainly by using the human visual system, we classify the original image, then according to the classification, we quantize their difference among nearby DCT coefficients and adjust them, to implement blind watermark algorithm. The experimental results show our algorithm has very excellent robust to usual image manipulation. 2 Digital Watermark ProtocolPropose a full watermark protocol structure for copyright protection. A perfect watermark structure is required to implement the digital watermark work's copyright protection. After analyzing the problem of watermark work's circulation, I try to propose a full watermark protocol structure. And introduce the authentication center (CA) for allocation and conservation of the secret key. The authentication center uses a time-stamp, which proves thewatermark embedded time and resists the interpretation attack effectively. At the same time, a trusted third party (TTP) is introduced to the open watermark, which brings out a feasible standard watermark model for the author, user and the authentication. And I analyses the resist ability of the model in the theory.