结合编码交织的频数质心零水印算法

针对传统数字水印算法的透明性随嵌入强度的增加而下降，且存在鲁棒性和稳定性差的问题，提出了一种基于极化码与二维交织算法相结合的频数质心零水印算法.该算法依次对水印信息进行极化码编码，二维交织构造出交织矩阵，然后对载体图像进行非下采样轮廓波变换获得其低频系数，再通过分块非负矩阵分解得到一维基矩阵；根据频数分布特征计算局部频数质心以构造出特征矩阵，最后将含有水印信息的交织方阵和特征矩阵进行异或操作生成零水印.大量实验表明，该零水印算法可以有效地抵抗常规的信号处理攻击、几何攻击以及组合攻击，水印提取的归一化系数值在0.88以上，具有较强的鲁棒性和稳定性，且具有良好的实用价值.

Frequency Centroid Zero Watermarking Algorithm Combine with Coding Interleaving

The transparency of traditional digital watermarking algorithms decreases with the increase of embedding strength, and their robustness and stability are poor. To solve these problems a frequency centroid zero watermarking algorithm based on polarization code and two-dimensional interleaving algorithm is proposed. In the proposed algorithm,the watermark information is encoded by polarization code in turn,and the interleaving matrix is constructed by two-dimensional interleaving. Then, the low-frequency coefficients of the carrier image are obtained by non-subsampled contour transform. Next, the one-dimensional matrix is obtained by block non-negative matrix decomposition. According to the characteristics of frequency distribution,the local frequency centroid is calculated to construct the feature matrix. Finally, the exclusive or operation of the interlaced matrix and the feature matrix containing watermark information are carried out to generate zero watermark. Experimental results show that the zero watermarking algorithm can effectively resist conventional signal processing attacks,geometric attacks and combinatorial attacks,and the normalized coefficient of watermark extraction is more than 0.88,which is robust and stable for practical applications.