YCbCrSubsampleRatio422
	YCbCrSubsampleRatio420
	YCbCrSubsampleRatio440
	YCbCrSubsampleRatio411
	YCbCrSubsampleRatio410
)

func (s YCbCrSubsampleRatio) String() string {
	switch s {
	case YCbCrSubsampleRatio444:
		return "YCbCrSubsampleRatio444"
	case YCbCrSubsampleRatio422:
		return "YCbCrSubsampleRatio422"
	case YCbCrSubsampleRatio420:
		return "YCbCrSubsampleRatio420"
	case YCbCrSubsampleRatio440:

	options := &Options{Quality: 90}
	for i := 0; i < b.N; i++ {
		Encode(io.Discard, img, options)
	}
}

func BenchmarkEncodeYCbCr(b *testing.B) {
	img := image.NewYCbCr(image.Rect(0, 0, 640, 480), image.YCbCrSubsampleRatio420)
	bo := img.Bounds()
	rnd := rand.New(rand.NewSource(123))
	for y := bo.Min.Y; y < bo.Max.Y; y++ {
		for x := bo.Min.X; x < bo.Max.X; x++ {
			cy := img.YOffset(x, y)
			ci := img.COffset(x, y)

		subsampleRatio = image.YCbCrSubsampleRatio444
	case 0x12:
		subsampleRatio = image.YCbCrSubsampleRatio440
	case 0x21:
		subsampleRatio = image.YCbCrSubsampleRatio422
	case 0x22:
		subsampleRatio = image.YCbCrSubsampleRatio420
	case 0x41:
		subsampleRatio = image.YCbCrSubsampleRatio411
	case 0x42:
		subsampleRatio = image.YCbCrSubsampleRatio410
	default:
		panic("unreachable")
	}

		{"YCbCr.Y", Field, 0},
		{"YCbCr.YStride", Field, 0},
		{"YCbCrSubsampleRatio", Type, 0},
		{"YCbCrSubsampleRatio410", Const, 5},
		{"YCbCrSubsampleRatio411", Const, 5},
		{"YCbCrSubsampleRatio420", Const, 0},
		{"YCbCrSubsampleRatio422", Const, 0},
		{"YCbCrSubsampleRatio440", Const, 1},
		{"YCbCrSubsampleRatio444", Const, 0},
		{"ZP", Var, 0},
		{"ZR", Var, 0},
	},
	"image/color": {