}

// 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))
	return YCbCr{y, u, v}
}

// NYCbCrA represents a non-alpha-premultiplied Y'CbCr-with-alpha color, having

	default:
		rgba, _ := m.(*image.RGBA)
		ycbcr, _ := m.(*image.YCbCr)
		for y := bounds.Min.Y; y < bounds.Max.Y; y += 16 {
			for x := bounds.Min.X; x < bounds.Max.X; x += 16 {
				for i := 0; i < 4; i++ {
					xOff := (i & 1) * 8
					yOff := (i & 2) * 4
					p := image.Pt(x+xOff, y+yOff)
					if rgba != nil {
						rgbaToYCbCr(rgba, p, &b, &cb[i], &cr[i])
					} else if ycbcr != nil {

		}:
			tc.SetRGBA64(1, 1, color.RGBA64{0x7FFF, 0x3FFF, 0x0000, 0x7FFF})

		case *NYCbCrA:
			memset(tc.YCbCr.Y, 0x77)
			memset(tc.YCbCr.Cb, 0x88)
			memset(tc.YCbCr.Cr, 0x99)
			memset(tc.A, 0xAA)

		case *Uniform:
			tc.C = color.RGBA64{0x7FFF, 0x3FFF, 0x0000, 0x7FFF}

		case *YCbCr:
			memset(tc.Y, 0x77)
			memset(tc.Cb, 0x88)
			memset(tc.Cr, 0x99)

		case Rectangle:

pkg image, method (*NYCbCrA) SubImage(Rectangle) Image
pkg image, method (*NYCbCrA) YCbCrAt(int, int) color.YCbCr
pkg image, method (*NYCbCrA) YOffset(int, int) int
pkg image, type NYCbCrA struct
pkg image, type NYCbCrA struct, A []uint8
pkg image, type NYCbCrA struct, AStride int
pkg image, type NYCbCrA struct, embedded YCbCr
pkg image/color, method (NYCbCrA) RGBA() (uint32, uint32, uint32, uint32)
pkg image/color, type NYCbCrA struct

	// or CMYK)" as per
	// https://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/JPEG.html#Adobe
	// we assume that it is YCbCrK. This matches libjpeg's jdapimin.c.
	if d.adobeTransform != adobeTransformUnknown {
		// Convert the YCbCr part of the YCbCrK to RGB, invert the RGB to get
		// CMY, and patch in the original K. The RGB to CMY inversion cancels

		if m0.Bounds() != image.Rect(0, 0, 150, 103) {
			t.Errorf("%s: bad bounds: %v", tc, m0.Bounds())
			continue
		}

		switch m0 := m0.(type) {
		case *image.YCbCr:
			m1 := m1.(*image.YCbCr)
			if err := check(m0.Bounds(), m0.Y, m1.Y, m0.YStride, m1.YStride); err != nil {
				t.Errorf("%s (Y): %v", tc, err)
				continue
			}

	{"nrgbaNilSrc", vgradGreenNRGBA(90), nil, Src, color.RGBA{0, 46, 0, 90}},
	// Uniform mask (100%, 75%, nil) and variable YCbCr source.
	// At (x, y) == (8, 8):
	// The destination pixel is {136, 0, 0, 255}.
	// The source pixel is {0, 0, 136} in YCbCr-space, which is {11, 38, 0, 255} in RGB-space.
	{"ycbcr", vgradCr(), fillAlpha(255), Over, color.RGBA{11, 38, 0, 255}},
	{"ycbcrSrc", vgradCr(), fillAlpha(255), Src, color.RGBA{11, 38, 0, 255}},

		subsampleRatio = image.YCbCrSubsampleRatio410
	default:
		panic("unreachable")
	}
	m := image.NewYCbCr(image.Rect(0, 0, 8*h0*mxx, 8*v0*myy), subsampleRatio)
	d.img3 = m.SubImage(image.Rect(0, 0, d.width, d.height)).(*image.YCbCr)

	if d.nComp == 4 {
		h3, v3 := d.comp[3].h, d.comp[3].v
		d.blackPix = make([]byte, 8*h3*mxx*8*v3*myy)
		d.blackStride = 8 * h3 * mxx
	}
}

// Specified in section B.2.3.

					}
					return
				case *image.RGBA:
					drawCopyOver(dst0, r, src0, sp)
					return
				case *image.NRGBA:
					drawNRGBAOver(dst0, r, src0, sp)
					return
				case *image.YCbCr:
					// An image.YCbCr is always fully opaque, and so if the
					// mask is nil (i.e. fully opaque) then the op is
					// effectively always Src. Similarly for image.Gray and
					// image.CMYK.

pkg image, method (*NRGBA64) NRGBA64At(int, int) color.NRGBA64
pkg image, method (*RGBA) RGBAAt(int, int) color.RGBA
pkg image, method (*RGBA64) RGBA64At(int, int) color.RGBA64
pkg image, method (*YCbCr) YCbCrAt(int, int) color.YCbCr

# CL 129190043 png: make the encoder configurable, Jeff R. Allen <******@****.***>
pkg image/png, const BestCompression = -3
pkg image/png, const BestCompression CompressionLevel