Research On Digital Watermark Based On Print Materials

With great development of the net technology, the prevention and detection of multimedia is more and more important, and the information hiding technology developed. But what can't ignore is, a large amount of images present by way of printed materials; a lot of protecting methods of printed materials have been invented, but with many bugs, these methods are costly, therefore, a good and cheap method is wanted urgently.In this paper, the information hiding is introduced, the two importantbranches--the image scrambling and the digital watermark are discussedrespectively. The digital watermark was put forward in 1993, past recent years' discoveries; the researching importance of digital watermark has developed to attention to survive the affine transformation, geometric transformation and the A/D transformation of watermark.As the basic means for hiding huge image information, the scrambling of digital image makes the old image to a new disorderly image with a reversible transform. In this paper, the usually algorithms of scrambling are introduced and the effects of scrambling are analyzed; the experiment shows that the scrambling of digital image can achieve hiding old information .Furthermore, the applications of scrambling and merging in the transmit of image are discussed, the experiment indicate that, the images, which are attacked by cut or dirt, can be recovered according my algorithm.According to the current situation of the information hiding in printed materials, the affects in printing and scanning to image are discussed, the possible lose and distort of information in the print and scan processing arc analyzed; based that ,two information hiding methods in printed materials are showed, in the first method, which based DCT, the watermark signals are imbedded to a grey image , after printed with a high resolution ratio, the carrier image is scanned in the same resolution ration, the scanned image is filtered and resample, then the watermark image is extracted; in the second method, the amalgamation is applied, the image to hide is scrambled and imbedded in a grey image ,after printed with a high resolution ratio, the carrier image is scanned in the same resolution ration, the scanned image is filtered and resample, then the imbedded image is extracted. The experiment shows that, the images which extracted in the two methods arc better, in addition, the possible attacks to the printed materials arc simulated, such as tearing up, dirt, the experiment indicates that the two information hiding methods in thispaper can compensate those attacks and be used in printed materials copyright protection.Information hiding;Watermark Scrambling;Print materials;Print;Scan...