Color difference keying for openframeworks

Based on the method described here
http://www.blendedplanet.com/?Planet_Blog:Greenscreen_Keying

This addon uses opencv to calculate the color difference of a specific green tone. This has a major advantage over ofxChromaKey (https://github.com/underdoeg/ofxChromaKey) as this method is able to extract shadow information and produces a smoother result.
The drawback is however it will only work with a well lit greenscreen and is way less error resistant than chroma keying.

The result looks something like this (taken with a really crappy green background)
https://github.com/underdoeg/ofxGreenscreen/blob/9b153daf18aea40de72e06569703ffdd158fe7a1/example/bin/data/save/composition2.png