Researchers Of Robust Digital Image Watermarking Algorithm Based On Frequency Domain

As high development of multimedia network technology, digital image, audio, video and other digital products need effective copyright protection method, the traditional encryption technology now faces a big challenge. Digital watermarking technology provides a new way to protect multimedia information and make it use safely, it becomes a hot point in the research area of multimedia information safety.Robust digital watermarking technology is used in solution of copyright controversy, setting user marks and others. At present,the research of digital watermarking focused on discrete fourier transform(DFT) domain, Discrete cosine transform(DCT) domain, Discrete wavelet transform(DWT) domain and others, but its robustness need to be improved.This paper took digital image as research object, designed several algorithms for embedding and picking-up digital watermarking.First, this paper gave an brief introduction in terms of theory of the status quo ,basic model, usage area, category, typical algorithm, capability evaluation, scramble technology, Human vision system (HVS) and others in digital watermarking technology.Second, this paper provided three digital watermarking algorithms based on frequency. One is based on DFT. It scrambled watermarking information firstly, then separated the picture into blocks and got DFT transform, at last embedded pseudo random sequence which is from secret keys into amplitude of switching matrix, and got the information according relativity. Other is matrix singular value decomposition (SVD) watermarking algorithms. It based on system's robustness will be improved for picture's singular value has strong stability. Another one is DWT watermarking algorithms. It embedded watermarking information after single size resolving into small wave ordinal number after multi-size resolving, and got into scramble technology to improve system's robustness. Last, this paper introduced some concepts of multiscale geometrical analysis and curvelet transform theory. Because curvelet can showed this feature more 'sparsely' in the function included singular curve or singular side in two dimension space or multi-dimension space. This paper provided a robust digital watermarking technology algorithm based on curvelet transform. watermarking information was embedded into coarse scale coefficients after curvelet transforming, choose right embedding strength. Testing proved it has good invisibility and robustness.