The Research Of Digital Image Watermarking Algorithm Based On DCT And SVD

of computer and network, the daily life and work of human beings are becomingdigitalized and networked. A large number of private data are transformed in theInternet, and electrical commerce is more and more popular. All these challenge thetraditional method of copyright protection and technology of data security. Digitalwatermarking technology, as a main method of providing copyright protection, hasbeen used widely and become the research focus in the field of information hiding.The history of digital watermarking development, states, basic model, charac-teristics, classification, and current main algorithm of the digital watermarking areintroduced. Then, a kind of watermarking algorithm based on the property of singularvalue decomposition (SVD) and discrete cosine transform (DCT) is proposed.Firstly, chaos map is applied in this algorithm. The proposed scheme uses chaoticsequence twice: first to disorder the original mark; second to resolve the distortionin the diagonal. Simulation results prove that the correlation coe?cient between thedisordered and the original mark is small. If the initial value of chaos is unknown,the characteristic watermarking can not be extracted correctly. Secondly, read somecoe?cients in low frequency subbands of Block-DCT domain by Zig-Zag order to creatematrix as the same size as the watermarking images, which not only enhance thecapacity of embedded information but also improve computational e?ciency. Finally,the digital watermarking is embedded by SVD, which can survive a variety of attacks.The algorithm adopts the integrated technologies of SVD, DCT and chaos encryption,therefore, theoretically, the digital watermark products base on the algorithm has betterperformance on secrecy and robustness.A great deal of experimental results are presented, which proving that the digitalwatermark generated by the algorithms are unperceivable and show great robustness tothe common image processing like low-pass filtering, median filtering, Wiener filtering,nosing, cropping, rotation and JPEG loss compression, etc. Furthermore, the algorithmis adaptive to all sorts of meaningful watermarks,and there is a good trade of betweencomputational e?ciency and information capacity of watermark, which has the usefultheoretical and practical value .