Design And Implementation Of The Double Digital Watermarking

Digital watermark technique is one of the most popular research topics in the field of the copyright protection of digital works, and it is also a new technique for the security protection of multimedia information. Many experts have done lots of research on the watermark and gained some achievements. In this dissertation, the history and origin of information hiding and digital watermark techniques are introduced firstly, which include the conception, theory, applications, classification, composing and algorithm.On the basis of discussing systematically the copyright protection of digital watermark and data authentication, an algorithm of the double digital watermark based on DCT is proposed. The algorithm includes two keys' watermark and public watermark, and realizes that text is embedded to image as watermark, and solutes the problem that watermark is non-significant, and got with original image. The algorithm can satisfy the transparence and robustness of the watermark system. Two keys' watermark is significant, it is also blind watermark. Public watermark is based on the public key cryptosystem, which makes it possible to realize data authentication and for user get watermark directly.This dissertation realizes the algorithm of the double digital watermark by MATLAB. The experiment shows that the watermark is effective to resist JPEG compressing, noise and the explanation attack.Finally, the work of the dissertation is summarized and the further research topics is proposed.