The Study And Apllication Of Digital Watermark In Printing Protecting Field

Safety printing is regarded as one of the trends of advanced printing in new century. The safety printing technology used by now, however, can't meet the commerce's requests. In this thesis, the watermark technologies were discussed in detail. The purposes of the research are to syncretize intersectant technology fields and extend the eyeshot of safety printing and provide it with technologies. The research can keep people and famous products from being attacked by fake commodities and promote the enterprise's great economic benefits and has important meaning in national economy's development.The main methods include:(l)Theory analyzing. Anatomizing the advantage and disadvantage of traditional safety printing methods and the theory and algorithm of DCT,DFT,DWT, the water marking is used firstly in safety printing field. According to the characteristic of DWT coefficient of picture analyzation, the watermark is adaptively embed into the low coefficient which represent the skelecton of original picture. (2)Experiments research. The experiments were designed based on the theoryof DWT, the original picture which include watermark was printed by high precision printer that over come the shortcomings that often appear in traditional printing work. The printed picture was scanned through the new style scanner which promoted the precision of experiment datum. The program of this system was compiled in VC++6. 0 which is a kind of OODs and is powerful. (3)Data process. The experiment datum were processed according to the characteristic of DWT distribution, the cause of picture error also was analyzed carefully.The mainly works done by the author as follows: (l)The author analyzed the character of printing pictures and designed the robust algorithm aim at the artifice of printing and scanning used by pirates. (2) According to the fundamental principles of the Information Theory, and Digital Image Processing, and Chromatology, integrating the Human Visual System (I1VS) and the texture of images, employing the characteristics of multi-resolution analysis of the two-dimension discrete wavelet transform (DWT) . The author proposes a safety printing system based on water marking and the theory frame and model. The experiment and validation also was done by the author.The main results include:(1) The robustness of the algorithm proposed by the author is strong, the error of pictures is neglected. The watermark has the invisibility and a strong robustness to the attack of printing and scanning. (2)The cost price was decreased effectively. The watermark can be regarded as effected proof in court.