I am pretty sure “Kraken.io's proprietery JPEG optimization algorithms” is based on the Psychovisual Error Threeshold: http://ieeexplore.ieee.org/document/65300

I am pretty sure “Kraken.io's proprietery JPEG optimization algorithms” is based on the Psychovisual Error Threeshold: http://ieeexplore.ieee.org/document/6530010/ http://ieeexplore.ieee.org/document/6530010/ Have a read at what Google engineer Colt McAnlis has to show about it: https://medium.com/@duhroach/reducing-jpg-file-size-e5b27df3257c https://medium.com/@duhroach/reducing-jpg-file-size-e5b27df3...