中文摘要：

针对二值水印信息量小的缺陷，提出一种基于DCT的图像灰度水印算法，通过修改DCT域中低频系数值来嵌入水印，易于实现。仿真实验证明本算法能够抵御剪切、噪声和JPEG压缩失真，具有良好的不可见性和鲁棒性。

英文摘要：

A gray level image watermarking algorithm based on DCT is put forward in this paper, aiming at the binary water- mark defeets. The gray level image watermark is embedded in the host image by modifying the chosen DCT medium frequency coefficients, which is easy to be implemented. The experiments have proved that the proposed algorithm is with strong robust- ness in resisting shear attracts, noise attracts, compression attracts, and other common attracts.