说明：  实现基本JPEG的压缩和编码分三个步骤: 1. 首先通过DCT变换去除数据冗余； 2. 使用量化表对DCT系数进行量化； 3. 对量化后的系数进行Huffman编码。
(Realize the basic JPEG compression and encoding is divided into three steps: 1. First of all, through the DCT transform to remove data redundancy 2. The use of quantization table of quantization DCT coefficients 3. Quantization coefficients after Huffman coding.)