A Research On Three Kinds Of Watermarking Technology

Digital watermarking is a new measure of digital media protection which are processes of embedding hidden messages within digital media such as text, images, video and audio to protect copyright .The hidden messages may be copyright information or secret messages .At the same time these messages have a very little influence on host media and have specific restore methods, These messages should be invisible to illegal receivers.This dissertation introduced the development of digital watermarking roundly, and the current study and application in this field all over the world, we reviewed the watermarking theories in detail. And the common structure of watermarking is discussed, its algorithms of embedding and detecting is studied. At last, three digital watermarking systems of different types are presented and evaluated.In chapter 1, we introduced the source of digital watermarking and its relation between information hiding, the method, target and meaning of this dissertation were presented. The over 10-year long history of digital watermarking and the achievement of former studies was mentioned in chapter 2, and we discussed the classic algorithm system , the structure model , and its special characters in this chapter too; In chapter 3, we introduced the important theoretic basis of watermarking on frequency domain, and focus on the latest wavelet analysis technology. According to the several different periods of watermarking technology, we presented a simple system on space domain, improved a system on DCT domain, and a system which applied with wavelet technology, all these three systems can be found in chapter 4 and 5, we explored in both static image and audio watermarking.