Watermarking Algorithm Based On Multi-scale Fractal Figures

In recent years, Internet is an excellent distribution system for digital media because it is cheap and fast. It is known that digital media can be easily replicated and modified. Thus, digital watermarking has been developed to protect the copyright and integrity of multi-media content.As a very important brand of nonlinear scientific research, fractal theory has spread over lots of areas of image processing including digital watermarking. In view of some algorithms to the robustness, the thesis conducts a primary research on the digital watermarking by fractal and Contourlet transform.Firstly, fractal coding is applied to the digital watermarking and traditional sub-block DCT algorithm is improved. The embedding and extraction was implemented with significance. Then, a new watermarking algorithm based on multifractal and two-dimension Logistic chaotic map is proposed. The algorithm is based on Contourlet and Wavelet. Performance comparison of the algorithm in both domains is performed. It demonstrates that Contourlet have future potential in watermarking. After that, as the request of verification and watermarking's developing direction, a new algorithm based on multifractal and Contourlet transform is proposed. When extracting watermark data, the algorithm does not need original image, and it realizes blind extraction. At last, in order to test imperceptibility and robustness of the algorithms, computer simulations on the three algorithms are performed, respectively. Experimental results show that on the condition of invisibility the algorithms have good robustness against common attacks such as JPEQ noise and so on.