PC影像壓縮技術(二) 續篇之JFIF -介紹 JFIF 檔案格式,本書已絕版

修改jpg文件的DPI值，能处理JFIF格式和EXIF格式-Modify the DPI value of the jpg file to be able to handle the JFIF format and EXIF ​ ​ format

TIFFTechNote2.txt.gz

The JPEG compression scheme is divided into the following stages: 1. Transform the image into an optimal color space. 2. Adjust Aspect Ratio 16:9 3. Digitization Scheme 4:2:0. 4. Apply a Discrete Cosine Transform (DCT) to blocks of pixels