【作者】 许玉冬；

【导师】 姚志强；

【作者基本信息】 福建师范大学 ， 应用数学， 2007， 硕士

【摘要】 在网络技术和多媒体技术迅速发展的数字信息时代，大量私有数据在网络上传播、交易，使传统的版权保护手段和数据安全技术面临极大的挑战和某些难以克服的困难，作为有效的版权保护手段的数字水印技术因而得到迅速发展。同时，隐藏分析技术及水印攻击技术也跟着发展，这就使得数字水印的安全性问题成为研究热点。本文归纳现有安全性定义，选用基于MRF(Markov随机场)图像模型的安全性测度来分析几种典型的图像数字水印方案的安全性。实验分析表明在傅立叶变换域、小波变换域和Contourlet变换域实现的水印方案其安全性度量(意味水印的不可感知性或不可检测性)优于余弦变换域、脊波变换域的水印方案。接着提出一种新的基于特征点领域定位和B样条多分辨率表示的稳健水印算法，仿真实验结果表明该算法不仅具有较好的抗攻击能力，而且从视觉效果上看是不可觉察的(定性)。最后定量分析该算法的安全性测度，这个测度值反映该算法较之余弦变换域、脊波变换域、傅立叶变换域以及小波变换域的数字水印方案具有更好的不可感知或不可检测性。本文也从实验角度观察安全值与PSNR值之间的关系。更多还原

【Abstract】 As the network technique and multimedia technique are developing quickly,plenty of personal datas are transmitted and traded on network. This makestraditional copyright protection and security technique face tremendouschallenge and some difficulty.Thus digital watermark technique as aneffective protect method also develops quickly. Synchronously, thetechniques of conceal analysis and watermark attacks also get a development.So the security of digital watermark become a hotspot for research in recentyears. This paper sums up exisiting security definitions, and selects asecurity measure based on MRF(markov random field) model for images, toanalyse the security of some typical digital watermark projects in image.The experiment result shows that the security measures(it means theperformance not to be felt or detected of watermark) of the watermark projectsin DFT, DWT and Contourlet Transform are prior to that in DCT or RidgeletTransform. Then a robust digital watermark method which bases on orientationin feature point field and B-spline curve multiresolution represendtationis put forward. The experiment result shows that it not only has a goodperformance to resist attacks but also is imperceptible(qualitative).At lastit analyses the security of this method quantitatively. The measure valueshows that the method has a better security, namely it is more difficult tobe felt or detected than the watermark projects in DCr, Ridgelet Transform, DFTand DWT. Also this paper observe the relation between security value and PSNRvalue by experiment.更多还原