【作者】 谭秀湖；

【导师】 李秀坤；

【作者基本信息】 哈尔滨工程大学 ， 信号与信息系统， 2006， 硕士

【摘要】 随着计算机的普及和Internet的广泛使用，数字音响制品以及其它电子出版物的传播和交易变得越来越便捷，但随之而来的侵权和盗版活动也呈日益猖獗之势。数字水印是实现版权保护的有效办法，已经被广泛应用于授权认证，版权保护，指纹识别和数字签名等许多方面。本文主要研究数字图像的水印嵌入算法及算法的安全性和鲁棒性的分析。本文的主要研究工作和取得主要成果如下： 1．针对数字图像的版权保护问题，提出一种基于特征空间分解的非对称数字水印方法，即首先通过对数字图像的特征空间的进行分解，将水印嵌入到最少受图像改变影响的子空间中，因而使得嵌入的水印具有鲁棒性，同时，由于嵌入水印的矩阵(密钥)与提取水印的矩阵(公钥)不同，我们可以公开除了密钥外所有其他所有的信息。并且通过对水印嵌入的特征子空间的选取进行了限制，因此我们提出的水印方法具有高的检测概率和安全性，低的虚警概率。仿真得到的各种攻击实验结果，都表明了基于特征空间分解的非对称水印方法具有良好的鲁棒性。 2．在统计意义最优的基础上，提出了一种非对称盲提取的数字水印算法。统计最优中的最小均方误差是通过对特征空间的选取，将水印嵌入到最少受图像操作的亚空间，从而使得由图像操作带来的误差均方最小；而且通过对公钥的构造，使得公钥与误差矢量正交，从而实现了无偏。同时，由于嵌入水印的矩阵(密钥)与提取水印的矩阵(公钥)不同，我们可以公开除了密钥外所有其他所有的信息，而且可以盲提取。因此我们提出的水印方法具有高的检测概率和安全性，低的虚警概率。仿真得到的各种攻击实验结果，都表明了基于最优统计意义下的数字水印方法具有良好的鲁棒性。 3．针对基于奇异值分解(SVD-Based)数字水印方法的安全性问题，进行了详细的分析并且给出了改进方法。水印通过SVD—Based方法嵌入到图像中，可以用不同的密钥从这幅图像中提取出不同的数字水印，即提取的水印不同于嵌入的水印。因此，基于SVD—Based的数字水印嵌入方式存在着安全性问题。为克服原SVD算法中的问题，对SVD—Based进行了改进。消除可以更多还原

【Abstract】 With the growth of network and multimedia technology, the copyright protection of multimedia becomes more and more important. Watermark technology, as a main method of providing copyright protection, has been widely studied and applied. In the paper, we mostly discuss the principle of digital watwemarking algorithm and the analysis of its security and robustness. The main reseach work and contributions of the dissertation rea as follow:1. To the problem of copyright protection, we propose an asymmetric watermarking method based feature space decomposing. Passing feature space decomposing of digital image, we obtain that the robustness of the approach lies in hiding a watermark in the subspace that is least susceptible to potential modification. In the same time, because we use different matrix operation to embed (secret key) and extract (public key) a watermark, we are able to release all information for the public., except the secret key. Through analysis and constraint the conditions, we can obtain a high detection probability and security, a low false alarm probability. The robustness of our method is demonstrated by various attacks through computer simulation.2. We obtain that the robustness of the approach lies in hiding a watermark in the subspace that is least susceptible to potential modification. And through analysis and constraint the conditions, we can obtain a high detection probability and security, a low false alarm probability. In the same time, because we use different matrix operation to embed (secret key) and extract (public key) a watermark, we are able to release all information for the public, except the secret key. Our method can extract the embedded watermark without reference image. The robustness of our method is demonstrated by various attacks through computer simulation 3. To the security problem of digital watermarking based on the singular value更多还原