中文说明：实现了JPEG标准的图像编译码流程。读取一个灰度图像，采用DCT变换、量化、Zigzag扫描和游程编码等步骤实现编码，译码端采用对应的逆操作进行译码。程序中可设置不同的量化系统，实现不同的压缩比和压缩效果。
English Description：
The coding and decoding process of JPEG standard is realized. A gray image is read and coded by DCT transform, quantization, zigzag scanning and run length coding. The decoder uses the corresponding inverse operation to decode. Different quantization systems can be set in the program to achieve different compression ratio and compression effect.