为了提高空间域彩色图像零水印算法的水印嵌入、检测的精度, 以及抵抗旋转几何变换的能力, 提出一种基于对数极坐标和四元数实矩表示的抗旋转攻击空间域零水印算法。将原始彩色图像使用四元数实矩阵来表征, 计算实数字矩阵的Hu不变矩; 利用7个Hu不变矩来设计和构建零水印信息; 在水印检测前, 通过对数极坐标校正算法,对可能遭受旋转攻击的待检测图像进行旋转角度的遍历, 而后进行水印的提取。实验获得了良好的图象视觉效果, 对于旋转几何攻击具有很强的鲁棒性, 同时对于滤波, JPEG压缩, 剪切攻击也具有一定的鲁棒性。

In order to improve the accuracy of the embedding watermark and the ability to resist rotation geometric transformation, a zero watermarking algorithm based on LPM (Log polar mapping) transform and real matrix of quaternion is proposed. The real matrix of quaternion is used to represent the original color image. The Hu invariant moments of the real matrix are calculated. Seven of Hu invariant moments are used to design and construct zero watermarking information. Before the watermarking image is detected, correcting the rotation angle of waiting detection image that may be subjected rotation attack, then the watermark is extracted. The experiment obtains better visual effect. It is robust enough to rotation attack. It is also robust enough to some mage degradation process such as filtering, JPEG compression and cropping attack.