https://github.com/robotpy/robotpy-cscore
These are python bindings for the FIRST cscore library, a high performance
library used to serve video to/from robots. They should work on Linux and OSX, and may also work on Windows too. I've only tested on Linux at this time.
Documentation is very light, and no precompiled binaries are currently available (expect end of January). However, it should work, and the basic examples work (
here's a simple image processing demo). I would highly recommend using this as the base of your python image processing code, instead of my previously recommendation of mjpg-streamer.
Try it out, let me know how it goes!