# File lib/color/cmyk.rb, line 174 def to_grayscale c = 0.299 * @c.to_f m = 0.587 * @m.to_f y = 0.114 * @y.to_f g = 1.0 - [1.0, c + m + y + @k].min Color::GrayScale.from_fraction(g) end