摘要： 在离散小波变换的基础上，提出了一种自适应的新数字水印算法，将伪随机二值序列作为水印嵌入灰度图像中，在检测端需要原始宿主图像。该算法具有以下特点：在水印嵌入时利用了小波变换域系数的均值，可广泛地适用于各种灰度图像；针对每幅图像，都可调节水印的嵌入深度，找到隐形性和鲁棒性的最佳折中。实验结果表明，该算法既实现了水印的隐形性，又对常见的图像处理操作具有很强的鲁棒性。

关键词: 数字水印, 离散小波变换, 鲁棒性, 宿主图像

Abstract: An adaptive image watermark algorithm based on wavelet transform is proposed. It adds pseudorandom sequence onto gray image and the host image is required for detecting the watermark. The algorithm has two characteristics: it is adapted to various gray images owing to using the mean value of selected coefficients; The appropriately embedded depth can be found for every gray image. Experiment results show that the proposed algorithm is invisible and robust against common image processing.

Key words: Digital watermark, Discrete wavelet transform, Robust, Host image