DCT

代码说明：

  将图象分块(8*8)，作DCT变换，并作IDCT：DCT是一种可分离图象变换，用来图象压缩编码，IDCT用来解压缩。(The image sub-block (8* 8) for the DCT transform, and to make IDCT: DCT is a separable image transformations, is used to image compression coding, IDCT is used to decompress.)