it used to default to 255, now it sniff the interpretation and defaults to 65535 for RGB16 and GREY16 see https://github.com/jcupitt/libvips/issues/449
it used to default to 255, now it sniff the interpretation and defaults to 65535 for RGB16 and GREY16 see https://github.com/jcupitt/libvips/issues/449