image/internal/imageutil: inline the color.YCbCrToRGB calls.
The image/draw benchmark:
benchmark old ns/op new ns/op delta
BenchmarkYCbCr 1198605 978647 -18.35%
Change-Id: Iacfc21e6f641ecb05adc00b3aec0048f1f43d265
Reviewed-on: https://go-review.googlesource.com/7952
Reviewed-by: Rob Pike <r@golang.org>
diff --git a/src/image/internal/imageutil/gen.go b/src/image/internal/imageutil/gen.go
index 59125da..cde05ad 100644
--- a/src/image/internal/imageutil/gen.go
+++ b/src/image/internal/imageutil/gen.go
@@ -47,7 +47,6 @@
import (
"image"
- "image/color"
)
// DrawYCbCr draws the YCbCr source image on the RGBA destination image with
@@ -94,10 +93,33 @@
dpix := dst.Pix[y*dst.Stride:]
yi := (sy-src.Rect.Min.Y)*src.YStride + (sp.X - src.Rect.Min.X)
%s
- rr, gg, bb := color.YCbCrToRGB(src.Y[yi], src.Cb[ci], src.Cr[ci])
- dpix[x+0] = rr
- dpix[x+1] = gg
- dpix[x+2] = bb
+
+ // This is an inline version of image/color/ycbcr.go's func YCbCrToRGB.
+ yy1 := int(src.Y[yi])<<16 + 1<<15
+ cb1 := int(src.Cb[ci]) - 128
+ cr1 := int(src.Cr[ci]) - 128
+ r := (yy1 + 91881*cr1) >> 16
+ g := (yy1 - 22554*cb1 - 46802*cr1) >> 16
+ b := (yy1 + 116130*cb1) >> 16
+ if r < 0 {
+ r = 0
+ } else if r > 255 {
+ r = 255
+ }
+ if g < 0 {
+ g = 0
+ } else if g > 255 {
+ g = 255
+ }
+ if b < 0 {
+ b = 0
+ } else if b > 255 {
+ b = 255
+ }
+
+ dpix[x+0] = uint8(r)
+ dpix[x+1] = uint8(g)
+ dpix[x+2] = uint8(b)
dpix[x+3] = 255
}
}
diff --git a/src/image/internal/imageutil/impl.go b/src/image/internal/imageutil/impl.go
index 5a156e4..d4bd325 100644
--- a/src/image/internal/imageutil/impl.go
+++ b/src/image/internal/imageutil/impl.go
@@ -4,7 +4,6 @@
import (
"image"
- "image/color"
)
// DrawYCbCr draws the YCbCr source image on the RGBA destination image with
@@ -44,10 +43,32 @@
ci := (sy-src.Rect.Min.Y)*src.CStride + (sp.X - src.Rect.Min.X)
for x := x0; x != x1; x, yi, ci = x+4, yi+1, ci+1 {
- rr, gg, bb := color.YCbCrToRGB(src.Y[yi], src.Cb[ci], src.Cr[ci])
- dpix[x+0] = rr
- dpix[x+1] = gg
- dpix[x+2] = bb
+ // This is an inline version of image/color/ycbcr.go's func YCbCrToRGB.
+ yy1 := int(src.Y[yi])<<16 + 1<<15
+ cb1 := int(src.Cb[ci]) - 128
+ cr1 := int(src.Cr[ci]) - 128
+ r := (yy1 + 91881*cr1) >> 16
+ g := (yy1 - 22554*cb1 - 46802*cr1) >> 16
+ b := (yy1 + 116130*cb1) >> 16
+ if r < 0 {
+ r = 0
+ } else if r > 255 {
+ r = 255
+ }
+ if g < 0 {
+ g = 0
+ } else if g > 255 {
+ g = 255
+ }
+ if b < 0 {
+ b = 0
+ } else if b > 255 {
+ b = 255
+ }
+
+ dpix[x+0] = uint8(r)
+ dpix[x+1] = uint8(g)
+ dpix[x+2] = uint8(b)
dpix[x+3] = 255
}
}
@@ -61,10 +82,32 @@
for x, sx := x0, sp.X; x != x1; x, sx, yi = x+4, sx+1, yi+1 {
ci := ciBase + sx/2
- rr, gg, bb := color.YCbCrToRGB(src.Y[yi], src.Cb[ci], src.Cr[ci])
- dpix[x+0] = rr
- dpix[x+1] = gg
- dpix[x+2] = bb
+ // This is an inline version of image/color/ycbcr.go's func YCbCrToRGB.
+ yy1 := int(src.Y[yi])<<16 + 1<<15
+ cb1 := int(src.Cb[ci]) - 128
+ cr1 := int(src.Cr[ci]) - 128
+ r := (yy1 + 91881*cr1) >> 16
+ g := (yy1 - 22554*cb1 - 46802*cr1) >> 16
+ b := (yy1 + 116130*cb1) >> 16
+ if r < 0 {
+ r = 0
+ } else if r > 255 {
+ r = 255
+ }
+ if g < 0 {
+ g = 0
+ } else if g > 255 {
+ g = 255
+ }
+ if b < 0 {
+ b = 0
+ } else if b > 255 {
+ b = 255
+ }
+
+ dpix[x+0] = uint8(r)
+ dpix[x+1] = uint8(g)
+ dpix[x+2] = uint8(b)
dpix[x+3] = 255
}
}
@@ -78,10 +121,32 @@
for x, sx := x0, sp.X; x != x1; x, sx, yi = x+4, sx+1, yi+1 {
ci := ciBase + sx/2
- rr, gg, bb := color.YCbCrToRGB(src.Y[yi], src.Cb[ci], src.Cr[ci])
- dpix[x+0] = rr
- dpix[x+1] = gg
- dpix[x+2] = bb
+ // This is an inline version of image/color/ycbcr.go's func YCbCrToRGB.
+ yy1 := int(src.Y[yi])<<16 + 1<<15
+ cb1 := int(src.Cb[ci]) - 128
+ cr1 := int(src.Cr[ci]) - 128
+ r := (yy1 + 91881*cr1) >> 16
+ g := (yy1 - 22554*cb1 - 46802*cr1) >> 16
+ b := (yy1 + 116130*cb1) >> 16
+ if r < 0 {
+ r = 0
+ } else if r > 255 {
+ r = 255
+ }
+ if g < 0 {
+ g = 0
+ } else if g > 255 {
+ g = 255
+ }
+ if b < 0 {
+ b = 0
+ } else if b > 255 {
+ b = 255
+ }
+
+ dpix[x+0] = uint8(r)
+ dpix[x+1] = uint8(g)
+ dpix[x+2] = uint8(b)
dpix[x+3] = 255
}
}
@@ -94,10 +159,32 @@
ci := (sy/2-src.Rect.Min.Y/2)*src.CStride + (sp.X - src.Rect.Min.X)
for x := x0; x != x1; x, yi, ci = x+4, yi+1, ci+1 {
- rr, gg, bb := color.YCbCrToRGB(src.Y[yi], src.Cb[ci], src.Cr[ci])
- dpix[x+0] = rr
- dpix[x+1] = gg
- dpix[x+2] = bb
+ // This is an inline version of image/color/ycbcr.go's func YCbCrToRGB.
+ yy1 := int(src.Y[yi])<<16 + 1<<15
+ cb1 := int(src.Cb[ci]) - 128
+ cr1 := int(src.Cr[ci]) - 128
+ r := (yy1 + 91881*cr1) >> 16
+ g := (yy1 - 22554*cb1 - 46802*cr1) >> 16
+ b := (yy1 + 116130*cb1) >> 16
+ if r < 0 {
+ r = 0
+ } else if r > 255 {
+ r = 255
+ }
+ if g < 0 {
+ g = 0
+ } else if g > 255 {
+ g = 255
+ }
+ if b < 0 {
+ b = 0
+ } else if b > 255 {
+ b = 255
+ }
+
+ dpix[x+0] = uint8(r)
+ dpix[x+1] = uint8(g)
+ dpix[x+2] = uint8(b)
dpix[x+3] = 255
}
}
