bench(b, color.RGBAModel, color.RGBAModel, nil, Src)
}

func BenchmarkNRGBAOver(b *testing.B) {
	bench(b, color.RGBAModel, color.NRGBAModel, nil, Over)
}

func BenchmarkNRGBASrc(b *testing.B) {
	bench(b, color.RGBAModel, color.NRGBAModel, nil, Src)
}

func BenchmarkYCbCr(b *testing.B) {
	bench(b, color.RGBAModel, color.YCbCrModel, nil, Over)
}

func BenchmarkGray(b *testing.B) {

	return m.f(c)
}

// Models for the standard color types.
var (
	RGBAModel    Model = ModelFunc(rgbaModel)
	RGBA64Model  Model = ModelFunc(rgba64Model)
	NRGBAModel   Model = ModelFunc(nrgbaModel)
	NRGBA64Model Model = ModelFunc(nrgba64Model)
	AlphaModel   Model = ModelFunc(alphaModel)
	Alpha16Model Model = ModelFunc(alpha16Model)
	GrayModel    Model = ModelFunc(grayModel)

	if len(p) < 1 || len(p) > 256 {
		e.err = FormatError("bad palette length: " + strconv.Itoa(len(p)))
		return
	}
	last := -1
	for i, c := range p {
		c1 := color.NRGBAModel.Convert(c).(color.NRGBA)
		e.tmp[3*i+0] = c1.R
		e.tmp[3*i+1] = c1.G
		e.tmp[3*i+2] = c1.B
		if c1.A != 0xff {
			last = i
		}
		e.tmp[3*256+i] = c1.A
	}
	e.writeChunk(e.tmp[:3*len(p)], "PLTE")

func sng(w io.WriteCloser, filename string, png image.Image) {
	defer w.Close()
	bounds := png.Bounds()
	cm := png.ColorModel()
	var bitdepth int
	switch cm {
	case color.RGBAModel, color.NRGBAModel, color.AlphaModel, color.GrayModel:
		bitdepth = 8
	default:
		bitdepth = 16
	}
	cpm, _ := cm.(color.Palette)
	var paletted *image.Paletted
	if cpm != nil {
		switch {
		case len(cpm) <= 2:

	}

	var cm color.Model
	switch d.cb {
	case cbG1, cbG2, cbG4, cbG8:
		cm = color.GrayModel
	case cbGA8:
		cm = color.NRGBAModel
	case cbTC8:
		cm = color.RGBAModel
	case cbP1, cbP2, cbP4, cbP8:
		cm = d.palette
	case cbTCA8:
		cm = color.NRGBAModel
	case cbG16:
		cm = color.Gray16Model
	case cbGA16:
		cm = color.NRGBA64Model
	case cbTC16:
		cm = color.RGBA64Model

	Pix []uint8
	// Stride is the Pix stride (in bytes) between vertically adjacent pixels.
	Stride int
	// Rect is the image's bounds.
	Rect Rectangle
}

func (p *NRGBA) ColorModel() color.Model { return color.NRGBAModel }

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

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

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

		{"NRGBA.R", Field, 0},
		{"NRGBA64", Type, 0},
		{"NRGBA64.A", Field, 0},
		{"NRGBA64.B", Field, 0},
		{"NRGBA64.G", Field, 0},
		{"NRGBA64.R", Field, 0},
		{"NRGBA64Model", Var, 0},
		{"NRGBAModel", Var, 0},
		{"NYCbCrA", Type, 6},
		{"NYCbCrA.A", Field, 6},
		{"NYCbCrA.YCbCr", Field, 6},
		{"NYCbCrAModel", Var, 6},
		{"Opaque", Var, 0},
		{"Palette", Type, 0},
		{"RGBA", Type, 0},

pkg image/color, var AlphaModel Model
pkg image/color, var Black Gray16
pkg image/color, var Gray16Model Model
pkg image/color, var GrayModel Model
pkg image/color, var NRGBA64Model Model
pkg image/color, var NRGBAModel Model
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