Quote Originally Posted by AgX View Post
You are mixing things up:

-) a laboratory made graph intended for comparison (where by added filtration the layers are exposed to yield a neutral grey).
What do you mean by filtration? Do you mean putting a filter over the light source to make it a more neutral color?..I have read that the ideal visual neutral curve is said to be a flat horizontal line, but such a curve would only appear a neutral grey if the spectral power distribution of the light source were uniform. Anything that deviates from uniform would introduce a warm or cool tint to the grey(accept for maybe a 5000K, that approximately looks neutral).