抗强剪切攻击的四元数彩色图像零水印算法

A Zero Color Image Watermarking Resisting Strong Cropping Attacks Using Quaternion Representation

针对现有彩色图像零水印算法对存在信息量丢失的各种攻击(如剪切、行列移除、涂抹等)的不足,提出一种基于非负矩阵分解(NMF)和四元数实矩阵的彩色图像零水印算法。该算法首先提取彩色图像的3个分量(R、G、B)并将各分量进行NMF分解;其次将分解后的各系数矩阵在版权中心进行注册,同时将原始彩色图像使用四元数实矩阵来表征,并计算实数字矩阵的Krawtchouk不变矩;最后,在版权中心注册Krawtchouk不变矩特征向量;由剩余未剪切部分的彩色图像和注册的系数矩阵共同恢复出完整的原始图像。实验结果表明:在彩色图像剪切或涂抹面积超过80%时,水印信息仍可以正确地被提取;使用四元数彩色图像整体法表征图像在图像类聚以及水印误检率方面的性能都要优于彩色图像三通道分别处理或直接灰度化实现的效果。

For some zero color image watermarking methods are insufficient for several attacks of information loss, a zero color image watermarking algorithm based on nonnegative matrix factorization and real matrix of quaternion is proposed. Firstly, three components （R, G, B） are extracted from color image and each component is decomposed. Secondly, the coefficient matrix decomposed is registered in the copyright center and the real matrix of quaternion is used to represent the original color image, also the krawtchouk invariant moments of the real matrix is calculated. Finally, some krawtchouk invariant moments are used to design and construct zero watermarking information. The experimental results show that original color image under strong shear can be recovered by residual shear part. When the area of shearing color image exceed 80%, watermark information can still be extracted correctly. This performance in image clustering and watermark error detection rate by using the quaternion to represent the whole color image is better than using each of three channels of color image processing or gray image directly.