针对彩色图像的版权保护问题,基于QR矩阵分解提出了一种自嵌入全盲水印算法。先将原始图像的G通道分量进行非下采样剪切波变换,再对得到的低频分量分块QR分解,通过判断各子块R矩阵中第一行元素向量的l1范数与所有子块R矩阵第一行元素l1范数均值之间的大小关系生成特征水印。然后对B通道分量DWT变换后的低频分量进行分块QR分解,并通过修改该子块QR分解后R矩阵中第一行最后一列元素来嵌入特征水印。特征水印的生成和嵌入在两个通道内独立完成,水印检测无需原始载体图像,算法无需借助外加水印信息即可完成对图像版权的鉴别。实验结果表明,该算法在经历添加噪声、JPEG压缩、缩放、剪切和行偏移等常见攻击时,具有很强的鲁棒性。
A novel self-embedding perfectly blind watermarking algorithm is proposed based on QR matrix decomposition for copyright protection of digital color images. At first, G channel component of the original image is performed with non-subsampled shearlet transform, then the low-frequency component is performed with block-QR decomposition, the feature watermark is derived by judging the number relationship between vector l1 norm from the first row elements of each sub-block's R-matrix and the mean of vector l1 norms from the first row elements of all sub-block's R-matrix. Secondly, the low-frequency component is obtained after DWT from B channel of original image, then it is performed with block-QR decomposition. The feature watermark is embed by modifying the first row and the least column element of the R-matrix from every blocks. The generation and embedding of feature watermark are done in two channels independently, the watermark can be detected without the original image, and the algorithm can identify an image without the additional watermark information. Experimental results show that the proposed algorithm has strong robustness to resist various common attacks such as adding noise, JPEG compression, scaling, cropping and row shifting.