Here is an article about a new JPEG Encoder - Guetzli JPEG Encoder. It produces up to 35% smaller files by better compression.
The pictures have fewer artifacts than standard jpegs.
The algorithm is open source and you can find it at github. Demo programs for Windows, Linux, etc. (32 or 64bit) are also available.
The results will be fantastic, if you have big jpeg file (e.g. 5 MB jpeg compressed to 1-2 MB.).
The only disadvantage is the slower speed of the jpeg encoder. The reason is the missing multi core support. It takes much time.
========https://research.googleblog.com/2017/03 ... -jpeg.html
Guetzli JPEG encoder binaries (Windows/Linux/etc.):