提出了一种基于DWT域的彩色图像数字水印算法，选取离散小波变换的中低频系数进行了水印的嵌入。选择了一种具有实际意义的二值图像作为水印图像，然后根据水印图像的不同值，在中频系数的不同方向上，改变系数2次嵌入了数字水印，以提高其鲁棒性。实验结果表明：该算法具有很好的隐蔽特性，并且对椒盐噪声、高斯噪声、中值滤波、图像旋转、图像缩放和JPEG压缩处理等操作具有很强的鲁棒性。

A new color image watermarking algorithm was proposed based on DWT domain and mid frequency coefficients were select to embed watermark. A meaningful binary image was chosen as watermark image and then according to watermark image value, the watermark was embedded two times by modifying the intensity in the middle frequency coefficients of the two different directions. Experimental results showed that the proposed algorithm has better imperceptibility, robustness to salt and pepper noise, additive Gaussian noise, median filtering, image rotate, image scaling and JPEG compression processing operation etc.