transfer_rgb_to_rec709
return transfer_rgb_to_rec709(transfer_srgb_to_rgb(v));
*r = transfer_rgb_to_rec709(*r);
*g = transfer_rgb_to_rec709(*g);
*b = transfer_rgb_to_rec709(*b);
transfer_rgb_to_rec709(i / (16.0 * 255.0))),