Abstract: The existing watermarking algorithm based on image moments has the disadvantages of small capacity, large complexity and its robustness should be improved in further study. A new zero-watermarking against geometric attacks was proposed. Using the image normalization and the features of Tchebichef moments, the rotation normalized Tchebichef moments of original image was calculated in the unit circle, and the upper-left corner of Tchebichef moments was scanned into numerical matrix. Afterwards, binary secret key was generated according to numerical matrix and watermark image, and saved to zero-watermarking information database. In detection, the same process was executed to draw out numerical matrix from the unauthenticated image, and watermark image was extracted by using the secret key and numerical matrix. The experimental results show that this algorithm is robust against rotation attacks of random angles, scaling attacks and common signal processing operations, even combined attacks.

Key words: zero-watermarking, Tchebichef moment, image normalization, geometric attack, robustness

摘要： 由于目前基于图像矩技术的水印算法水印容量小，算法复杂，鲁棒性有待提高，提出一种新颖的抗几何攻击的零水印算法。该算法以图像归一化技术和Tchebichef矩系数的特点为基础，首先计算原始图像单位圆内旋转归一化的Tchebichef矩，将Tchebichef矩的左上角部分扫描成数值矩阵;然后根据数值矩阵和水印图像生成二进制密钥并保存到零水印信息库。证明版权时待检测图像也按相同的流程处理，利用密钥和生成的数字矩阵提取待检测图像的水印。实验结果表明，该算法对任意角度的旋转、缩放和常规信号处理及其组合攻击具有很强的鲁棒性。

关键词: 零水印, Tchebichef矩, 图像归一化, 几何攻击, 鲁棒性