在对原图像进行双正交7／9三级小波分解后 ，在第二级的水平、垂直、对角以及第三级对角分量上加入水印系数，再经过小波反变换重构出图像。-in the original image Biorthogonal 7 / 9 3 wavelet decomposition, in the second-class level, vertical, diagonal, and the third-class right angle to add weight coefficient watermark, after wavelet-transform reconstruct images.