DCT变换：变换域系数选取采用阈值编码，：阈值越小，图像恢复效果越好，但压缩效果差，一般取在5-10 即可很好的获得恢复图像信息。-DCT transform: transform domain coefficients selected using the threshold coding: the smaller the threshold value, the better the image restoration, but the compression is poor, and generally in the 5-10 to get a good recovery image information.