MPEG Based Wartermark Technology Research

Digital watermark technology has been introduced to protect the copyright of digital products in recent years. With this technology, you can embed the copyright information and authentication information such as the author or others. And as the complementarity of cipher technology, it can identify the digital product which has been illegally copied, and it can protect the legal copied product. Because of these merits, the watermark technology has been hot since its appearance.Now there are many papers on digital watermark technology, but most of them are focused on how to design a sheme or how to attack a watermark. And most of these themes or products are not so perfect because relexation of the basic theory about digital watermark technology. We can say that we are still in the early time of this technology and there are many difficulties.In this paper, the usage of watermark technology, especially in the MPEG system, is discussed. The technology of static watermark and the MPEG watermark techonology are compared. We consider the possibility to apply the static wartermark technology on MPEG system directly, and we also consider the problems may occur. At last, a new method of embeding and detecting watermark are introduced with the result of experiments.In chapter1, the backgroud and the state of watermark technology are introduced. In chapter2, we discuss the basic theory and the method of watermarking used frequently. In chapter 3 and chapter 4, the MPEG encoding algorithm and its file format are introduced. In chapter 5, we discuss where to embed the watermark based on the MPEG's encoding algorithm, the differences between MPEG system and static image are considered, we also discuss how to mesure the qulity of a kind of watermarking method.In chapter 5, a spatial method of watermarking is applied on the MPEG system directly, we analyse the result and discuss the fault of this method. We also test another method based on DCT transform, find its fault and consider how to avoid.At last, a new method based on DCT transform is considered, we test it and get a better result than the two methods we have discussed.