基于Contourlet变换和SVD的数字水印算法

摘要

通过对轮廓波多尺度分解与奇异值分解(SVD)的研究,实现一种基于Contourlet变换的双重嵌入算法.为解决算法的安全性问题,对水印图像采用双因子加密的方法;加密后的水印图像经过SVD后双重嵌入到Contourlet变换的低频系数和合适的方向子带中,为水印的提取增加一次机会.水印提取过程中,获取原宿主图像的奇异值,可以提取水印,因此是一种近似盲提取算法.仿真和攻击实验结果表明,与其它算法进行比较分析,该算法的不可见性和鲁棒性得到了一定提高.%Through the study of decomposition coefficients for multi-scale contours wave and singular value decomposition,a double embedding algorithm based on Contourlet transform was designed.To solve the problem of the algorithm security,two-factor encryption method was used for the watermark image,which changed the image histogram and provided double protection for algorithm.After encryption and SVD,watermark image was dually embedded into low frequency coefficients of Contourlet transform and suitable directional sub bands,adding an opportunity to extract the watermark.The watermark was extracted through the singular values of the original host image,so it was an approximate blind extraction algorithm.Results of simulation and experiment show that compared to other algorithms,the invisibility and robustness of the algorithm are improved.