jpeg-archive

jpeg-archive (https://github.com/danielgtaylor/jpeg-archive) may be the better use case images that you don't intend to have downloaded a billion times. I tried jpeg-compress -c in.jpg out.jpg (-c skips output that is bigger than the original) and got visually good results, lower file sizes, and quick processing. The file size ultimately will be larger the guetzli, but not by that much more and it doesn't take an extremely long time to compress one image.

The main innovation here is using advanced simulation of how humans perceive distortions (https://github.com/google/butteraugli) and optimizing to that. In principle JPEG was always about removing details humans can't see, but in practice encoders used rough approximations and fixed quality settings. This one goes all-in on accurate measurement and tuning quality settings per image automatically. In lossy compression quality setting affects file size much more than choice of image format (e.g. there's 15-30% difference in best quality/filesize between old codecs like JPEG/J2K/VP8/JXR, but within each codec's settings range the file size can vary by 300%), so having a codec that picks the lowest good-enough quality is very useful. Compared to MozJPEG: - it's tuned for higher-quality images (butteraugli is said to be best for q=90+, MozJPEG