抗旋转攻击的小波域数字水印算法

DWT Domain Digital Watermarking Algorithm against Rotation Attacks

为了提高基于小波变换的数字水印算法抵抗图像旋转攻击的能力,文章提出一种抗旋转攻击的小波域数字水印算法。对于旋转造成的几何攻击,我们可通过Radon变换计算原始图像水印在角度为0°的一组投影参照向量R0和待检测图像在0°～359°之间的投影参照向量R,然后对R的每一组投影参照向量与R0作相关系数计算。找到其相关系数最大的投影参照向量所对应的角度θ。在水印检测前先利用角度θ对图像进行几何校正,然后进行水印的提取。通过仿真实验结果证明,该方法可以获得良好的图像视觉效果,对于旋转几何攻击具有很强的鲁棒性,同时对于加噪、滤波、JPEG压缩、剪切攻击也具有很好的鲁棒性。

In order to improve the digital image watermarking method in DWT domain against rotation attack ability,this paper proposes one method based on Radon transform,which can against rotation attack efficiently.For rotation causing distortion,we make use of radon transform to compute the projection reference vector R0 of original image at angle 0 and the reference vectors R of test image at angles from 0 to 359,then,using the projection reference vector R0 to make normalized correlation computation with each group of reference vectors R and finding the angle θ,according to the max value of normalized correlation computation.Finally,we can detect test image involves watermarking or not.The experiment results demonstrate the proposed method can obtain better visual effect,it is robust enough to all kinds of rotation attacks,and meanwhile,it is also robust enough to some mage degradation process such as adding noise,cropping,filtering and JPEG compression.