基于多尺度分形的数字水印算法研究

【作者】 韩玉兰；

【导师】 蒋爱平；

【作者基本信息】 黑龙江大学 ， 信号与信息处理， 2010， 硕士

【摘要】 近年来,随着数字通信的发展,计算机网络“廉价而快速”的特性得到了数字多媒体传输的青睐。但是众所周知,数字多媒体在传输过程中极易被复制和修改。因而,作为保护数字多媒体产品知识产权的重要技术,数字水印技术受到国内外学者的关注,并得到了广泛的研究与应用。分形作为非线性科学的一个重要分支,已经渗透到包括数字水印在内的图像处理的各个领域。针对现有的部分数字水印算法在鲁棒性方面的不足,本文研究了分形理论和Contourlet变换在数字水印方面的应用。论文主要进行了如下工作：首先,将分形编码应用到了数字水印中,改进了传统的分块DCT域水印算法的鲁棒性,实现了有意义水印的嵌入与提取。其次,提出了一种多重分形和二维Logistic混沌映射相结合的图像水印算法,该算法是基于Contourlet和Wavelet的。比较了算法在两种变换域的水印性能,从而确认Contourlet在图像水印方面的发展潜力。第三,根据有权验证的需要和水印算法的发展方向,提出了一种结合多重分形和Contourlet变换的图像水印新算法。该算法在水印提取时不需要原始图像,实现了水印的盲提取。最后,本文对所提出的算法做了大量的鲁棒性实验,实验表明,三种算法在满足不可见的条件下,能够较好的抵抗JPEG.添加噪声等一些常见攻击。更多还原

【Abstract】 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.更多还原