What Color is White?
The secret chameleon
When I first began painting classes, I was taught to think of white (as in the tubed version) as a blue. It’s true, mostly. Add white to orange and it “blues” or cools it. Add it to cad yellow medium, and you do not get cad yellow light; you get an icky version of cad yellow medium. Add it to ultramarine blue (to a certain level) and not only does it lighten the ultramarine, but it also makes it sing even more. So yes, in this sense, I do believe that white acts like a blue. Note here, please, that I am talking about the raw, dry pigment (i.e., PW1, PW4, PW6, etc.), not visible light in the spectrum.
I think of this when I am mixing paint. But when identifying color in a scene, it is the furthest thing from my mind. Ah, white, the secret chameleon. Absolutely everything affects it. The green grass bouncing up onto the side of a white house, the blue of the sky as it overtakes a white shadow, the ambient occlusion, the penumbra,