Compress Images

Google open sourced guetzli (GitHub). I ran it against my photos, I am seeing 30-50% smaller size as results. It did take a long time to compress, but that's fine.

Twitter also announced their use of guetzli for better image quality:

Install guetzli and use it like so:

guetzli input.jpg output.jpg

The only caveat is you can't compress PNG with transparency. Sometimes guetzli also made the resulted image size larger, fallback to ImageOptim.