手写jpg压缩和解压，理解JPEG的压缩原理. JPEG压缩分为4部分
1.下采样 2.量化 3.离散余弦变化 4.哈夫曼压缩。分别对于Day2, Day3, Day4, Day5
Day1是读取需要压缩的图片, Day6是输出jpeg文件.

A one step by step project that teaches people how JPEG works.
Day1, reading pixels data from BMP files.
Day2, subsampling pixels.
Day3, DCT discrete cosine transform.
Day4, quantization
Day5, huffman entropy compress.
Day6, outpuf jpg file.

完结于2021.2.13 all done in Feb 13,2021

Thanks for reading.

对应的JEPG的解释. https://www.cnblogs.com/robsann/p/14397929.html