将图片分割成8*8的块然后进行DCT和量化，编码及解码(For further improvement each 8x8 block of the difference image can be transformed using a 2D DCT before quantizing and coding)

jpg编解码，提取DCT系数，dc系数和ac系数的哈夫曼编码表等(Jpg coding and decoding, extracting DCT coefficients, DC coefficients and AC coefficients Huffman coding table, etc.)