Abstract: Presents a robust digital watermarking algorithm based on invariant feature of image. Watermarking messages are embedding into wavelet domains of image in this method ; Before watermarking detection, makes use of stable SIFT feature points of image to estimate geometric distortion factors and corrects watermarked image ,then detects right watermarking messages. The experimental results show the algorithm is robust to geometric attack such as cropping , rotation, scaling .

Key words: watermarking, SIFT feature points, geometric distortion, estimate affine factors

摘要： 提出了一种基于图像不变特征的鲁棒数字水印算法。该方法在图像的小波域中嵌入水印；在水印检测之前，利用图像中稳定的SIFT(尺度不变特征变换)特征点估计几何失真参数，对可能失真的水印图像进行校正，从而可以准确的提取水印信息。实验结果表明,该算法对剪裁、旋转、缩放等各类几何攻击具有很好的鲁棒性。

关键词: 数字水印, SIFT特征点, 几何失真, 参数估计