HFP4 ChromaKey. I love the flexibility this key gives but I have always had a problem when keying out green screen where there are blues - especially light blues or turquoises in the sections I want to keep. The colour is just drained out of the - sometimes turning it a sort of purple.
I assume this is something to do with there being either a lot of "G" in the colour I want to leave, or a lot of "B" in the sections I want to remove. However I do not get thi issue with the Colour Difference Key.
I'd put it down to my camera (although its a Canon XF100 - which shoots 4:2:2) and/or lighting, but I've since tried this with different kit and outdoor overcast lighting and have the same issue.
Any suggestions as to how to overcome this? (I've hitherto been working around it by copying a layer and rotoscoping over the blue bits - rather tedious)