dip4

代码说明：

  对原始灰度图像进行图像压缩，对此图进行 8×8 DCT 变换后，分别只保留 DC系数，以及保留前 4、8、16 个变换系数(DC＋AC) ，然后再分别进行 IDCT 变换 (The original gray image compression, this map for 8 × 8 DCT transform, respectively, to retain only the DC coefficient, and to retain the former 4,8,16 months transform coefficients (DC+ AC), and then separately IDCT transform)