【作者】 杨格兰；

【导师】 熊岳山；

【作者基本信息】 国防科学技术大学 ， 计算机科学与技术， 2006， 硕士

【摘要】 数字水印是信息安全、版权保护等的重要手段，研究安全、鲁棒的水印技术是一项具有挑战性的研究，有广泛的应用前景。本文重点研究水印的安全性和鲁棒性。提出用混沌加密方式研究水印的加密技术，详细分析了四个小波子带上奇异值性质，提出了两种在小波域子带中修改奇异值系数的水印算法。1)基于DWT-SVD(Discrete Wavelet Transform-Singular Value Decomposition)鲁棒的图像水印嵌入与提取算法。该方法通过把水印嵌入到图像经过一级小波变换后的四个子带上，通过原图像小波变换后四个奇异值子带与水印图像的最大奇异值系数关系，自适应地嵌入水印图像。实验表明，该算法能够抵抗各种常见攻击，尤其对复合攻击有很强的鲁棒性。2)基于DWT-SVD的鲁棒盲水印算法。该方法通过确定PSNR(Peak Signal to Noise Ratio)建立水印嵌入强度和图像质量的关系，使水印算法能确定水印的最优嵌入能量来量化变换域，以达到同时满足图像的不可察觉性和鲁棒性，并能够实现盲提取，最后对量化嵌入算法进行了误差分析。实验结果表明有很好的鲁棒性。在水印的安全性方面，本文在深入研究图像的置乱技术的基础上，提出了一种基于二值图像的混沌加密算法，给出了对二值图像的置乱度评价指标，实验表明，混沌加密／解密效率高、运算量不大、密钥量大，安全性好等优点。最后，对本文中建立的算法用Visual C++ 6.0编程设计了一个数字图像水印处理系统软件，主要用于进行数字图像的加密／解密、水印的嵌入、提取与鲁棒性检测实验等，测试验证本文算法的可行性与水印的鲁棒性。更多还原

【Abstract】 The digital watermarking is an important means to provide the copyrightprotection、information security, therefore the research of secure and robust digitalwatermarking technique is still challenging research, also remains a popular applicationforeground.It is important to study more secure and robust watermark in this paper. Firstly,this paper put forwards an image encryption algorithm based on chaotic binarysequences, which has well effect to encrypt watermark picture. Secondly, we presenttwo hybrid scheme based on the Discrete Wavelet Transform(DWT) and Singular ValueDecomposition(SVD) by means of the analysis of features of wavelet sub-blockssingular value and influence degree between the commonly used image processingtechnique and noise interference.1) Based on the algorithm of DWT-SVD robust watermark image embedding andextracting.Decomposing the cover image into four bands, we apply the SVD to each band,and embed the same watermark data by modifying the singular values. Modification inall frequencies allows the development of a watermarking scheme that is robust to awide range of attacks. We observed that the scaling factor can be chosen from a fairlywide range of values for LL, and also for the other three bands, the scaling factor can bechosen according to the relation of maxim singular value coefficient betweensub-blocks and watermark. Experiment results show that the algorithm can resist allkinds of classical attacks, specially, the strong robustness for anti-compound attacks.2) Robust blind watermarking algorithm based on DWT-SVDDWT-SVD domain watermarking is put forward by the picture PSNR analysis andquantization watermark’s error analysis, we can determine the best energy or capacity tobe added to the original image. Experiments and attacks test show that the algorithm hasgood robustness.In order to ensure the security of the watermark system, this paper gives an imageencryption algorithm based on chaotic binary sequences, also improves algorithm ofgray distance to evaluate the effect of binary image encryption. By experimenting onchaotic sequence sensitivity on their initial condition, the scrambling of distance pixels,and the encrypting and de-encrypting speed of images, the result shows that theencryption algorithm effect is good and low computational complexity and highsecurity.Finally, based on the proposed scheme and Microsoft Visual C++ 6.0 environment,we have designed a corresponding software system for watermark embedding,watermark extracting, image encryption, de-encrypting and watarmark robustness detecting, etc.更多还原