Why do pictures generally turn green instead of other colors after repeated compression?
This is a test of simulated iterative compression done by God: https://m13253.github.io/JPEGreen/. The first-ranked answer has been very careful. I don’t know much about image compression. I will take a pit first and learn later. The answerer pointed out that it has nothing to do with JPEG. The reason is that a bug that appeared in Android in order to improve the running speed has been fixed. The answers of other respondents also extended to the problem of repeated uploading, downloading and saving. In this case, it will not turn green, but it will become blurred, the hue types will be reduced, and the saturation will be reduced. In the end, it can no longer be viewed, but it has also reached a bottleneck. That is, the image quality is maintained at a low level.
In addition to turning green, the emoji may also appear water ripples, which is actually the Gibbs phenomenon. Zhihu has related explanations, here .
reference:
https://fotomen.cn/2015/02/27/download/ Instagram experiment, upload and download a photo repeatedly 90 times
https://m13253.github.io/JPEGreen/
https://www.zhihu.com/question/68135290/answer/260156559 Gibbs phenomenon