src1.SetCMYK(x, y, color.CMYK{
					uint8(13 * x % 0x100),
					uint8(11 * y % 0x100),
					uint8((11*x + 13*y) % 0x100),
					uint8((31*x + 37*y) % 0x100),
				})
			}
		}
		src = src1
	case color.GrayModel:
		src1 := image.NewGray(image.Rect(0, 0, srcw, srch))
		for y := 0; y < srch; y++ {
			for x := 0; x < srcw; x++ {
				src1.SetGray(x, y, color.Gray{
					uint8((11*x + 13*y) % 0x100),
				})
			}
		}

	NRGBAModel   Model = ModelFunc(nrgbaModel)
	NRGBA64Model Model = ModelFunc(nrgba64Model)
	AlphaModel   Model = ModelFunc(alphaModel)
	Alpha16Model Model = ModelFunc(alpha16Model)
	GrayModel    Model = ModelFunc(grayModel)
	Gray16Model  Model = ModelFunc(gray16Model)
)

func rgbaModel(c Color) Color {
	if _, ok := c.(RGBA); ok {
		return c
	}
	r, g, b, a := c.RGBA()

		switch cb {
		case cbG8:
			if gray != nil {
				offset := (y - b.Min.Y) * gray.Stride
				copy(cr[0][1:], gray.Pix[offset:offset+b.Dx()])
			} else {
				for x := b.Min.X; x < b.Max.X; x++ {
					c := color.GrayModel.Convert(m.At(x, y)).(color.Gray)
					cr[0][i] = c.Y
					i++
				}
			}
		case cbTC8:
			// We have previously verified that the alpha value is fully opaque.
			cr0 := cr[0]

	if !(Point{x, y}.In(p.Rect)) {
		return
	}
	i := p.PixOffset(x, y)
	p.Pix[i] = color.GrayModel.Convert(c).(color.Gray).Y
}

func (p *Gray) SetRGBA64(x, y int, c color.RGBA64) {
	if !(Point{x, y}.In(p.Rect)) {
		return
	}
	// This formula is the same as in color.grayModel.
	gray := (19595*uint32(c.R) + 38470*uint32(c.G) + 7471*uint32(c.B) + 1<<15) >> 24
	i := p.PixOffset(x, y)

	var d decoder
	if _, err := d.decode(r, true); err != nil {
		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,

				break
			}
		} else {
			if d.stage >= dsSeenIHDR {
				break
			}
		}
	}

	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:

		{"CMYKToRGB", Func, 5},
		{"Color", Type, 0},
		{"Gray", Type, 0},
		{"Gray.Y", Field, 0},
		{"Gray16", Type, 0},
		{"Gray16.Y", Field, 0},
		{"Gray16Model", Var, 0},
		{"GrayModel", Var, 0},
		{"Model", Type, 0},
		{"ModelFunc", Func, 0},
		{"NRGBA", Type, 0},
		{"NRGBA.A", Field, 0},
		{"NRGBA.B", Field, 0},
		{"NRGBA.G", Field, 0},
		{"NRGBA.R", Field, 0},