Research And Implementaiong Of Multi-Functional Watermarking

With the rapid development of computer network technology, the storage and copy of the digital multimedia technique, more and more emphasis is paid on copyright protection and verification of digital products. Digital watermarking protects the copyright and content authentication by embedding some secret information, which is called watermark. The existence of the watermark in the digital products should not influence the quality of the original digital product obviously and it is difficult to remove the watermark. There are many papers about robust digital watermarking, but papers about fragile digital watermarking are fewer. Thus, there search of multi-functional digital watermarking is usually ignored.In this paper, a kind of multi-functional digital watermarking is provided, which can be applied to copyright protection, user tracking and content authentication at the same time. The multi-functional watermark is divided into two parts: robust watermark and fragile watermark. The robust watermark is used to provide the copyright protection of image and user tracking; the fragile watermark is used for authentication of the content. The author devised core algorithms with detailed performance analysis and computer simulations. The main contribution of this paper is listed as follows:1. The algorithm of robust watermarking, which implemented copyright protection was based on the characteristic of systematic code in RS error correcting code. Aimed at client and Certificate Authority, this algorithm designed two different extracting methods, which ensured two different requirements of robustness.2. The algorithm of robust watermarking, which implemented user tracking was based on SVD quantization and grouping inserting watermark. It reached the standard of strong robustness and could achieve 100% extracting with certain attracting.3. The algorithm of semi-fragile watermarking, which implemented the authentication of content was based on the main segments of image quality losing in JPEG2000 compression. The watermark is employing the self-characteristic of neighborhood. And the original image and original watermark is not in need while extracting. This algorithm was also provided the function of tampered positioning, which made this semi-fragile watermarking more practicability4. In the end, after author considering the influence between robust and semi-fragile watermarking, all functions above-mentioned were added into one image. The simulation results showed this kind of multi-functional digital watermarking provided copyright protection, user tracking as well as content authentication, and each function performed well.