# 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