Guetzli: Perceptually Guided JPEG Encoder: https://arxiv.org/abs/1703.04421Guetzli 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.
75% of users prefer Guetzli JPEG over same-sized libjpeg: https://arxiv.org/abs/1703.04416
Get the code here: https://github.com/google/guetzli/
Download binaries hiere: https://github.com/google/guetzli/releases
At some point in time, it would be nice to have Guetzli inside IM like libjpeg ... but as development is progressing quickly and atm apart from the quality there are zero config options a simple link to the cli exe (like with jxrenc an so on) would be nice.
Drawbacks: Guetzli generates only sequential (nonprogressive) JPEGs, and only for high quality >= 84 libjpeg equivalent setting.