The problem with green paint is: it is very difficult to pigment correctly.
Curiously, pure "green paint" should be VERY bright, almost lime color, just as said in here, the way you see a pure green 255 field on a tv monitor.
But the high luminosity of such paint cannot easily be produced because: Paint or dye are what is called the "subtractive synthesis" this means: White light, reflected from a pure white surface, bounces back passing through the "dye" which filters the reflected light, removing all red and blue components.
Perfect green dyes are difficult, specially for wall paint.
O the other hand, colors as seen on a computer monitor are produced by "Additive synthesis": Pure colored light is combined to produce the colors. A totally green screen is produced by a transparent green filter (within the LCD mosaic) and a pure white back light behind the mosaic in the LCD screen. So what we see is pure direct filtered light and not bounced back light.
In practical situations, where it is difficult to buy a green CK background, it is much easier to make a BLUE backing, with paint. Blue dyes are much better and the results are almost perfect blue reflected light.
So... What to do? Is up to your choice and paint availability.
I go BLUE in my school lab, and we get good chroma out if it. Also... Blue contamination in the superimposed video is easier to correct than green spill. Even a slightly blue contamination is not as bothersome as the green one. Blueish pictures are more tolerated than greenish ones...
What do you think about it?
Mike
Mike Aparicio-Reallusion Certified Innovative Content Developer