message: Clean up cymk_to_rgb code.
diff: @@ -95,12 +95,11 @@ fn cmyk_to_rgb(input: &[u8]) -> Vec<u8> {
  let y = f32::from(pixel[2]);
  let k = 255.0 - f32::from(pixel[3]);
  - let k_sub = -k;
  - let k = k * 255.0;
  + let k_mul = k * 255.0;
  // CMY -> RGB
  - let r = (c * k_sub + k) * inv;
  - let g = (y * k_sub + k) * inv;
  - let b = (m * k_sub + k) * inv;
  + let r = (k_mul - c * k) * inv;
  + let g = (k_mul - m * k) * inv;
  + let b = (k_mul - y * k) * inv;
  output.push(r as u8);
  output.push(g as u8);
  