# File lib/color/cmyk.rb, line 137 137: def to_grayscale 138: c = 0.299 * @c.to_f 139: m = 0.587 * @m.to_f 140: y = 0.114 * @y.to_f 141: g = 1.0 - [1.0, c + m + y + @k].min 142: Color::GrayScale.from_fraction(g) 143: end