基于Tchebichef矩和Logistic混沌加密的数字水印算法

目的针对现有的基于图像矩的数字水印算法比较复杂、鲁棒性差,尤其在抵抗缩放和旋转等攻击方面性能较差的问题,提出一种基于Tchebichef矩的数字水印算法。方法首先将载体图像进行非下采样Contourlet变换,得到与载体图像大小相同的低频子带,将低频子带分块后对各子块进行奇异值分解(SVD),根据奇异值的特点选择最佳嵌入位置,并由左奇异值和右奇异值矩阵自适应地计算水印嵌入强度,将通过Logistic混沌加密后的水印嵌入选中子块的奇异值中。计算含水印图像的Tchebichef矩,用于旋转及缩放校正。结果实验结果显示,文中算法的不可见性好,提取的水印NC值达到0.9386,能够有效抵抗旋转和缩放攻击。结论该算法对任意角度的旋转攻击和缩放攻击具有很好的鲁棒性,能够达到保护数字产品的目的。

Digital Watermarking Algorithm Based on Tchebichef Moments and Logistic Chaotic Encryption

The paper aims to propose a digital watermarking algorithm based on Tchebichef moments to solve the problems of large complexity and poor robustness of image moment based watermarking algorithms, especially the sensitivity to scaling and rotation attacks of watermarking which exists in digital watermarking algorithms. Firstly, the non-sampling contourlet transform of the host image was performed to obtain the low frequency sub-band with the same size as the host image. The low frequency sub-band was divided into blocks and singular value decomposition (SVD) was applied on the blocks. According to the characteristics of the singular value, the optimal embedding positions were selected. The embedding strength of the watermarking was calculated adaptively according to the characteristics of the left singular value matrix and the right singular value matrix. The watermark encrypted by Logistic chaos was embedded into the selected singular value to calculate Tchebichf moments of watermarked image for rotation and scaling correction. Experiments show that the algorithm had good invisibility and the NC value of the extracted watermarking reached 0.9386. It can effectively resist rotation and scaling attacks. The algorithm has strong robustness for resistance again rotation attacks at any angle and scaling attacks, and can protect digital products.