calculate white in cmyk

Question

I want to calculate the coverage of cmyk color + the coverage of white. I only have no clue of how to calculate the white.

if c, m, y, and k go from 0 to 1 is then white:

w = 1 - (c+m+y+k/4)

or is it:

w = 1- c-m-y-k (and the clamped to be 0 or above so it's not minus something)

Or is it more complex then that?

Answer 1

In one "standard definition" of CMYK, converting from RGB goes like this:

K=min(R,G,B)
C=(1-R-K)/(1-K)
M=(1-G-K)/(1-K)
Y=(1-B-K)/(1-K)

I think the level of white in a color would just be W=1-K, but I'm not entirely sure if that's what you're asking...