Quote Originally Posted by Stephen Benskin View Post
... Ralph, am I correct in assuming your equation comes from CIE? Could you break it down more and define the source of the variables?
Yes, the equation is the one currently used by CIE. The following link:

http://en.wikipedia.org/wiki/Lightness_(color)

shows the development of this equation from Priest (1920) through Munsel (1933) until CIE (1976).