基于Baker映射与时空混沌相结合的CT-QR域双彩色鲁棒盲水印算法

针对彩色水印图像的盲提取算法抗几何攻击鲁棒性不强的问题,提出一种Baker映射与时空混沌相结合的轮廓波变换(Contourlet transform,CT)和QR分解双彩色强鲁棒盲水印算法。首先将彩色水印分离成RGB分量,对三个分量分别进行Baker映射与时空混沌相结合的预处理操作,然后对载体图像的RGB分量分别进行Contourlet变换,分块QR分解得到酉矩阵,最后根据嵌入规则将加密后的水印分通道的嵌入到酉矩阵中。水印提取时利用Radon变换对图像进行几何校正可提高其几何攻击的鲁棒性。仿真结果表明,该算法不仅使嵌入水印后的图像具有良好的不可见性,而且能有效抵抗加噪、滤波、JPEG压缩、剪切、平移、旋转、马赛克、篡改等攻击,NC值均在0.9以上,对组合攻击也有较强的鲁棒性。 

Dual-color Robust Blind Watermarking Algorithm in CT-QR Domain Based on Baker Map and Spatio-temporal Chaos

In order to solve the problem that the blind extraction algorithm of color watermark image is not robust to geometric attacks, a dual-color robust blind watermarking algorithm based on contour wave transform (Contourlet transform) and QR decomposition based on Baker mapping and spatio-temporal chaos is proposed. Firstly, the color watermark was separated into RGB components, and the three components were preprocessed by the combination of Baker mapping and spatio-temporal chaos, then the RGB components of the carrier image were transformed by Contourlet, and the block QR decomposition was used to get the unitary matrix. finally, according to the embedding rules, the encrypted watermark was embedded into the unitary matrix. When the watermark was extracted, the geometric correction of the image using Radon transform can improve the robustness of geometric attacks. Simulation results show that the algorithm not only makes the embedded watermark image invisible, but also can effectively resist noise, filtering, JPEG compression, cropping, translation, rotation, mosaic, tampering and other attacks. The NC values are all above 0.9. it also has strong robustness to combined attacks.