Perceptual adaptive JPEG encoder

https://github.com/google/guetzli

Guetzli is a JPEG encoder that aims for excellent compression density at high visual quality. Guetzli-generated images are typically 20-30% smaller than images of equivalent quality generated by libjpeg. Guetzli generates only sequential (nonprogressive) JPEGs due to faster decompression speeds they offer.

https://forum.doom9.org/showthread.php?t=160577