【作者】 温泉；

【导师】 景晓军；

【作者基本信息】 北京邮电大学 ， 通信与信息系统， 2006， 硕士

【摘要】 数字水印系统存在两个关键问题：一是提高基于图像水印方式隐藏信息的安全性；二是解决水印透明性与鲁棒性之间的矛盾。 本论文主要针对LSB水印系统的算法保密性差的特点，研究了为隐藏信息加密的DES算法。通过对多种空域水印算法优缺点的分析，提出了基于DES算法的空域数字图像水印加入方法。引入的加密方法确保了隐藏信息的安全性，并利用VC++6.0对该方法进行了设计实现。实验表明，该方法在通信应用中有较强的实用性，同时也具备良好的透明性和可靠性。 目前的水印技术存在很多问题，例如算法的鲁棒性和透明性不好，水印信息嵌入量较少等，本文围绕着这些问题在DCT变换域展开研究。在此基础上，提出了基于DCT系数特性的水印算法，并通过一些常见的图像处理攻击实验验证了这种算法生成水印的性能。利用分块DCT系数的奇偶特性，并通过PN序列加密来保证水印的安全性。基于DCT系数特性的水印，利用分块DCT系数的周期特性，结合Zig-Zag编码置乱技术，提出一种在宿主图像的中频交流系数上嵌入二值水印图像的方案。 经过DCT域技术处理的水印图像因对其DCT系数的修改是在有损量化之后进行的，所以更具健壮性，算法能够成功地实现水印的嵌入与提取，而且运算速度较快。与传统图像水印的系统相比，本文提出的方案更具有抗干扰性，同时也具有很好的鲁棒性和透明性。所有的过程，包括嵌入、攻击、提取、验证均在MATLAB环境中进行模拟。更多还原

【Abstract】 There are two key problems in watermarking technique of digital images. One is how to improve the security of hiden information which is based on the method of digital watermarking technique and the other is how to deal with the conflict of robustness and transparency.The dissertation focuses on the security fragility of digital watermarking system based on LSB, develops the method based on DES algorithm to encrypt for the hiden information. With the analysis of many spatial domain watermark algorithms, a new spatial domain digital watermarking method based on DES is presented, which is implemented by VC++ 6.0.On the other hand, there are many problems in the current watermarking technique, such as the weakness of robustness and imperceptibility of algorithms and so on. The dissertation does some studies on DCT domain and a new watermarking algorithm based on the property of DCT coefficients is proposed. Then the design principles are simulated and the performances are validated through some common attack experiments of images. Furthermore, PN series is used to ensure watermarking security.With the periodic property of DCT coefficients and the digital image scrambling transformation namely Zig-Zag scan, we proposes a meaningful binary watermarking image embedding algorithm on block DCT intermediate frequency AC coefficients of the original image. The proposed algorithm is more practical and better than others at robustness and imperceptibility. All processes, including watermarking embedding, attacking, extracting and verifying, are simulated in MATLAB environment.更多还原