设计抗几何攻击的图像水印算法是数字水印技术研究中的难点。仿射变换是典型的几何攻击，能够使目前大多数数字水印算法失效。基于带边信息的水印模型，本文提出了一种利用Zernike矩的抗仿射变换多比特图像水印算法。该算法将归一化图像的Zernike矩作为边信息，利用量化技术对的水印信息进行编码和嵌入。实验证明，本文提出的算法不仅具有很好的抗仿射变换和抗JPEG压缩的鲁棒性，而且具有较小的嵌入失真和较大的水印容量。

Image watermarking resisting to geometric attacks is challenging at present. As typical geometric attacks, affine transformations can defeat most of existed watermarking schemes. Based on watermarking model with side information, a watermarking algorithm is proposed in this paper which is used of zernike moments of cover image. Employing dither modulation，watermark is coded and embedded by taking the zernike moments of the normalized image in the way of side information. It has been proved by experiments that this algorithm is high imperceptibility, high capacity, and robust to affine transformation and JPEG lossy compression.