src1.SetNRGBA(x, y, color.NRGBA{
					uint8(13 * x % 0x100),
					uint8(11 * y % 0x100),
					uint8((11*x + 13*y) % 0x100),
					0x7f,
				})
			}
		}
		src = src1
	case color.YCbCrModel:
		yy := make([]uint8, srcw*srch)
		cb := make([]uint8, srcw*srch)
		cr := make([]uint8, srcw*srch)
		for i := range yy {
			yy[i] = uint8(3 * i % 0x100)
			cb[i] = uint8(5 * i % 0x100)

	if uint32(b)&0xff000000 == 0 {
		b >>= 8
	} else {
		b = ^(b >> 31) & 0xffff
	}

	return uint32(r), uint32(g), uint32(b), 0xffff
}

// YCbCrModel is the [Model] for Y'CbCr colors.
var YCbCrModel Model = ModelFunc(yCbCrModel)

func yCbCrModel(c Color) Color {
	if _, ok := c.(YCbCr); ok {
		return c
	}
	r, g, b, _ := c.RGBA()
	y, u, v := RGBToYCbCr(uint8(r>>8), uint8(g>>8), uint8(b>>8))

type YCbCr struct {
	Y, Cb, Cr      []uint8
	YStride        int
	CStride        int
	SubsampleRatio YCbCrSubsampleRatio
	Rect           Rectangle
}

func (p *YCbCr) ColorModel() color.Model {
	return color.YCbCrModel
}

func (p *YCbCr) Bounds() Rectangle {
	return p.Rect
}

func (p *YCbCr) At(x, y int) color.Color {
	return p.YCbCrAt(x, y)
}

func (p *YCbCr) RGBA64At(x, y int) color.RGBA64 {

		return image.Config{}, err
	}
	switch d.nComp {
	case 1:
		return image.Config{
			ColorModel: color.GrayModel,
			Width:      d.width,
			Height:     d.height,
		}, nil
	case 3:
		cm := color.YCbCrModel
		if d.isRGB() {
			cm = color.RGBAModel
		}
		return image.Config{
			ColorModel: cm,
			Width:      d.width,
			Height:     d.height,
		}, nil
	case 4:
		return image.Config{

		{"RGBToYCbCr", Func, 0},
		{"Transparent", Var, 0},
		{"White", Var, 0},
		{"YCbCr", Type, 0},
		{"YCbCr.Cb", Field, 0},
		{"YCbCr.Cr", Field, 0},
		{"YCbCr.Y", Field, 0},
		{"YCbCrModel", Var, 0},
		{"YCbCrToRGB", Func, 0},
	},
	"image/color/palette": {
		{"Plan9", Var, 2},
		{"WebSafe", Var, 2},
	},
	"image/draw": {
		{"(Op).Draw", Method, 2},
		{"Draw", Func, 0},

pkg image/color, var Opaque Alpha16
pkg image/color, var RGBA64Model Model
pkg image/color, var RGBAModel Model
pkg image/color, var Transparent Alpha16
pkg image/color, var White Gray16
pkg image/color, var YCbCrModel Model
pkg image/draw, const Over Op
pkg image/draw, const Src Op
pkg image/draw, func Draw(Image, image.Rectangle, image.Image, image.Point, Op)