A Novel Digital Watermarking Algorithm Based On DCT And SVD

In course of mass usage and spreading of the digital multimedia products, the digital products are unavoidable illegally copied and tampered, which makes its information security and copyright protection a problem to be solved urgently. Taking use of the redundant data and randomicity of the digital products, the digital watermarking technology embeds the unperceivable but recognizable secret information-watermark containing the copyright information into the digital products, which can protect the copyright and integrality of the digital products. The digital watermarking technology has been used widely and become the research focus, which becomes an effective method to solve the digital information security problem, especially the copyright protection of digital products.After profound researching of current digital watermarking technology in worldwide, This theme proposed a new watermarking algorithm based on DCT (Discrete Cosine Transform) and SVD (singular value decomposition) according to the principle, characteristic and the advantages of the application of DCT and SVD theory in watermarking field. This provided algorithm in this paper have to firstly serialize the watermark character's lattice in order to improve the secrecy of the watermark signal and enhance the capability of handling the hostile attack before the watermark is embeded, and then divided the original image into small images according to the application characteristics of the DCT in the digital products, after dividing the original image, each small images has to be handled by means ofSVD------in fact, which add the watermark information to the value field of SVD, So,the signal embedded is randomized even if the original watermark text is meaningful, which will great improve the secrecy of the whole system. Compared with the conventional digital watermarking schemes, this algorithm, focusing on the protection of the meaningful watermark, has better performance on secrecy and robustness. The algorithm adopts the integrated technologies of SVD and DCT, therefore, theoretically, the digital watermark products has better performance on secrecy androbustness, and as a result, the algorithm introduced in this theme has great theoretical value and economic meaning in the protection of digital products.Finally, a great deal of experimental results generated by the algorithm based on DCTand SVD are presented in this theme, and the algorithm is also compared with the classical SVD embeded algorithm.The large numbers of results show that the algorithm can guarantee the unperceivability and transparency of the digital image, so this algorithm can have the same effect on the ordinary digital products in the aspects of robustness theoretically.The experimental process lay emphasis on the common image processing like cut process, fixes moving, JPEG loss compression, nosing and cropping, etc, the result showed the good performance of the algorithm referred in this theme, theoretically, the algorithm not only can work on the digital image, but also can work on the other digital products, so which has the useful theoretical and practical value in the meaningful digital watermark embedding process.