One of the approaches to solve the problem is suggested in the paper by Hungarian scientists Akos Borbely, Arpad Samson, and Janos Schanda, published in "Color Research and Application", Vol. 26, No. 6, Dec. 2001, "The Concept of Correlated Colour Temperature Revisited". You can find it online at:
Reading such articles and trying to make sense of them is guaranteed to fry the brain of we mere mortals. And, by the way, I consider myself to be a pretty darned smart and intelligent fellow, but I also have an insanely good sense of where my talents lie, and in this area they don't :lol: .
What I find most fascinating about all of this is the affect that Digital is having in this area. My guess is that unless something has fundamentally changed in the Physics of Light and Color, which I doubt, these issues have been with us forever, but because the Lab took care of all of this for us, as well as the film manufacturers, it was never an issue we could do much about as "mere" photographers.
Now that we are ALSO The Lab we are realizing just how much goes into the process that most of us may have been aware of, but never understood.
I've said it before and I'll say it again, thank whatever powers that be that we have folks like Iliah around to a) help folks like me get a better understanding and b) have the ability to actually use this knowledge to create tools for us.