基于Contourlet-DCT混合变换的零水印算法

摘要

Aiming to improve the security of watermark image and resolve the contradiction between robustness and the invisibility of watermark algorithm,a Contourlet-DCT hybrid transform zero-watermark algorithm is proposed in this paper.Firstly,two chaotic sequences are modulated by binary watermark image itself,and the result of modulation is used as the watermark image.Next,Contourlet and DCT transform are carried out in order to extract the energy characteristics.For the purpose of further improving the robustness,the extracted features are adopted singular value decomposition to get the singular value,in which the largest ones are chosen to rebuild feature matrix.Then,the feature matrix and the encrypted watermark are combined to form a registered watermark.At the end of this paper,the algorithm is compared with zero watermarking algorithm in wavelet domain.The results show that the hybrid domain zero watermarking algorithm is better than the latter.%为提高水印图像的安全性,并解决水印嵌入时鲁棒性与不可见性之间的矛盾,提出了一种基于Contourlet-DCT混合变换的零水印算法.首先,利用二值水印图像自身不同的像素值对两个混沌序列进行调制加密,并将调制后的结果作为加密的水印图像.接下来对载体图像依次进行Contourlet与DCT变换从中提取能量特征,再对提取的特征进行奇异值分解,选取其中最大的奇异值重组特征矩阵,最后把特征矩阵与加密后的水印图像结合生成注册水印.为验证算法的有效性,将该算法与传统的小波域零水印算法进行了比较,结果表明,混合域零水印算法在多项攻击测试中的鲁棒性均优于后者.