This is the classic 3 circles of light exibit that you can mix to make other colours. All three lights have brightness controls, so visitors can change to colour of light to anything they like. The lights are also moveable, allowing more interaction.
If you are mixing light you add colours together, and if you get the right mixture it will look white. When you mix pigments you start with white light, and remove colours. So the primary colours instead of being one of red, green or blue, they subtract red, green or blue, leaving cyan, magneta, or yellow.
It uses a camera and some software to simulate 3 different kinds of colourblindness.
Red green - by averaging the red and green channels to give a yellow channel (there are two subtley different forms from loosing the red or the green cone in the eye, but the actual sensitivity of the red and green cones are very similar)
Blue yellow - by loosing the blue cones