The Research And Implementation Of Multi-functional Watermarking

In recent years, with the development at full speed of the network technology, the storage and copy of the digital multimedia become very convenient. People can obtain information of multimedia conveniently through Internet and CD-ROM, which may influence the multimedia copyright protection and economic benefits of the authors. Therefore, multimedia copyright protection and content authentication have become serious problems that need to be solved urgently. Digital watermarking is developed to resolve these problems. 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, the research 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 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; The fragile watermark is used for authentication of the content . The embedding of robust watermark is based on wavelet transform and discrete cosine transform. Since this algorithm combines the merits of two transforms, it can get better performance. The fragile watermark is embedded in the high-frequency DCT coefficients. The simulation results show that this kind of multi-functional digital watermarking provides copyright protection as well as content authentication, and it also perform well under the attacks, such as noise, shear, compression.