Transform Digital Watermarking Based On Contourlet Optimize The Embedding Algorithm And Performance Analysis

At present, with the rapid development of Internet and multimedia technologies, the security of digital products has become the issues of particular concern. As a branch of the Information hiding, digital watermarking plays an important role in copyright protection and integrality authentication. In this dissertation, an overview of digital watermarking technology research situation was summarized firstly, and the basic framework and system model of digital watermarking were described in detail, and then on the basis of Contourlet transform theory, embedding and detecting algorithm of erasable watermarking and robust watermarking were explored. Finally, algorithm performance has been proved by experiment.The primary contributions of this dissertation contain the following points:A robust watermarking algorithm in Contourlet domain based on cloud model was proposed by researching on the theory, which was used for an uncertainty transforming between a qualitative concept and its numerical representation. Normal cloud generator algorithm and similar cloud measurement algorithm were to be extended to watermarking generation and detection. And a series of cloud droplet collection were seen as embedded watermark, the robustness of watermarking algorithm was further improved by randomness and fuzziness of cloud watermark. Base on cloud expectation curve, a novel similar cloud measurement algorithm was brought forward. Experimental results demonstrate that the proposed algorithm was invisible and able to effectively resist attacks such as JPEG, filtering, noise, cropping and so on.A novel dual watermarking algorithm in Contourlet domain was proposed according to practical applications. It implements both copyright protection and copyright notification by invisible robust watermark and visible removable watermark. This dissertation surveyed compressed sensing theory, which is used for sparse signal acquisition and reconstruction, and it was applied to the design of a visible translucent watermark algorithm. In this algorithm, measurement vector was embedded into Contourlet approximation. And the experimental results show that the algorithm not only can reconstruct sub-image with high quality but also provided security assurances. In order to exploit embedding algorithm of masking characteristics, HVS model was improved in Contourlet domain. And pseudo-random sequence watermark was embedded into Contourlet subbands. By statistical properties of subband coefficient analysis, correlation detection method was developed. Finally, the experimental results demonstrate that the algorithm achieve the excellent compromise between robustness and invisibility.