aw/go-resize
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Avoid temporaries to save some cycles.

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This commit is contained in:
jst 2014-01-17 22:54:15 +01:00
parent 7c5018c82b
commit 314cea6612
2 changed files with 40 additions and 47 deletions
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80
converter.go
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@ -43,94 +43,88 @@ func replicateBorder(x, y int, rect image.Rectangle) (xx, yy int) {
// the idea is to speed up computation by providing optimized implementations // the idea is to speed up computation by providing optimized implementations
// for different image types instead of relying on image.Image.At(). // for different image types instead of relying on image.Image.At().
type converter interface { type converter interface {
at(x, y int) colorArray at(x, y int, color *colorArray)
} }
type genericConverter struct { type genericConverter struct {
src image.Image src image.Image
} }
func (c *genericConverter) at(x, y int) colorArray { func (c *genericConverter) at(x, y int, result *colorArray) {
r, g, b, a := c.src.At(replicateBorder(x, y, c.src.Bounds())).RGBA() r, g, b, a := c.src.At(replicateBorder(x, y, c.src.Bounds())).RGBA()
return colorArray{ result[0] = float32(r)
float32(r), result[1] = float32(g)
float32(g), result[2] = float32(b)
float32(b), result[3] = float32(a)
float32(a), return
}
} }
type rgbaConverter struct { type rgbaConverter struct {
src *image.RGBA src *image.RGBA
} }
func (c *rgbaConverter) at(x, y int) colorArray { func (c *rgbaConverter) at(x, y int, result *colorArray) {
i := c.src.PixOffset(replicateBorder(x, y, c.src.Rect)) i := c.src.PixOffset(replicateBorder(x, y, c.src.Rect))
return colorArray{ result[0] = float32(uint16(c.src.Pix[i+0])<<8 | uint16(c.src.Pix[i+0]))
float32(uint16(c.src.Pix[i+0])<<8 | uint16(c.src.Pix[i+0])), result[1] = float32(uint16(c.src.Pix[i+1])<<8 | uint16(c.src.Pix[i+1]))
float32(uint16(c.src.Pix[i+1])<<8 | uint16(c.src.Pix[i+1])), result[2] = float32(uint16(c.src.Pix[i+2])<<8 | uint16(c.src.Pix[i+2]))
float32(uint16(c.src.Pix[i+2])<<8 | uint16(c.src.Pix[i+2])), result[3] = float32(uint16(c.src.Pix[i+3])<<8 | uint16(c.src.Pix[i+3]))
float32(uint16(c.src.Pix[i+3])<<8 | uint16(c.src.Pix[i+3])), return
}
} }
type rgba64Converter struct { type rgba64Converter struct {
src *image.RGBA64 src *image.RGBA64
} }
func (c *rgba64Converter) at(x, y int) colorArray { func (c *rgba64Converter) at(x, y int, result *colorArray) {
i := c.src.PixOffset(replicateBorder(x, y, c.src.Rect)) i := c.src.PixOffset(replicateBorder(x, y, c.src.Rect))
return colorArray{ result[0] = float32(uint16(c.src.Pix[i+0])<<8 | uint16(c.src.Pix[i+1]))
float32(uint16(c.src.Pix[i+0])<<8 | uint16(c.src.Pix[i+1])), result[1] = float32(uint16(c.src.Pix[i+2])<<8 | uint16(c.src.Pix[i+3]))
float32(uint16(c.src.Pix[i+2])<<8 | uint16(c.src.Pix[i+3])), result[2] = float32(uint16(c.src.Pix[i+4])<<8 | uint16(c.src.Pix[i+5]))
float32(uint16(c.src.Pix[i+4])<<8 | uint16(c.src.Pix[i+5])), result[3] = float32(uint16(c.src.Pix[i+6])<<8 | uint16(c.src.Pix[i+7]))
float32(uint16(c.src.Pix[i+6])<<8 | uint16(c.src.Pix[i+7])), return
}
} }
type grayConverter struct { type grayConverter struct {
src *image.Gray src *image.Gray
} }
func (c *grayConverter) at(x, y int) colorArray { func (c *grayConverter) at(x, y int, result *colorArray) {
i := c.src.PixOffset(replicateBorder(x, y, c.src.Rect)) i := c.src.PixOffset(replicateBorder(x, y, c.src.Rect))
g := float32(uint16(c.src.Pix[i])<<8 | uint16(c.src.Pix[i])) g := float32(uint16(c.src.Pix[i])<<8 | uint16(c.src.Pix[i]))
return colorArray{ result[0] = g
g, result[1] = g
g, result[2] = g
g, result[3] = float32(0xffff)
float32(0xffff), return
}
} }
type gray16Converter struct { type gray16Converter struct {
src *image.Gray16 src *image.Gray16
} }
func (c *gray16Converter) at(x, y int) colorArray { func (c *gray16Converter) at(x, y int, result *colorArray) {
i := c.src.PixOffset(replicateBorder(x, y, c.src.Rect)) i := c.src.PixOffset(replicateBorder(x, y, c.src.Rect))
g := float32(uint16(c.src.Pix[i+0])<<8 | uint16(c.src.Pix[i+1])) g := float32(uint16(c.src.Pix[i+0])<<8 | uint16(c.src.Pix[i+1]))
return colorArray{ result[0] = g
g, result[1] = g
g, result[2] = g
g, result[3] = float32(0xffff)
float32(0xffff), return
}
} }
type ycbcrConverter struct { type ycbcrConverter struct {
src *image.YCbCr src *image.YCbCr
} }
func (c *ycbcrConverter) at(x, y int) colorArray { func (c *ycbcrConverter) at(x, y int, result *colorArray) {
xx, yy := replicateBorder(x, y, c.src.Rect) xx, yy := replicateBorder(x, y, c.src.Rect)
yi := c.src.YOffset(xx, yy) yi := c.src.YOffset(xx, yy)
ci := c.src.COffset(xx, yy) ci := c.src.COffset(xx, yy)
r, g, b := color.YCbCrToRGB(c.src.Y[yi], c.src.Cb[ci], c.src.Cr[ci]) r, g, b := color.YCbCrToRGB(c.src.Y[yi], c.src.Cb[ci], c.src.Cr[ci])
return colorArray{ result[0] = float32(uint16(r) * 0x101)
float32(uint16(r) * 0x101), result[1] = float32(uint16(g) * 0x101)
float32(uint16(g) * 0x101), result[2] = float32(uint16(b) * 0x101)
float32(uint16(b) * 0x101), result[3] = float32(0xffff)
float32(0xffff), return
}
} }

7
filters.go
View File

@ -51,10 +51,9 @@ type filterModel struct {
tempRow []colorArray tempRow []colorArray
} }
func (f *filterModel) convolution1d(x float32, p []colorArray, factor float32) colorArray { func (f *filterModel) convolution1d(x float32, p []colorArray, factor float32) (c colorArray) {
var k float32 var k float32
var sum float32 = 0 var sum float32 = 0
c := colorArray{0.0, 0.0, 0.0, 0.0}
for j := range p { for j := range p {
k = f.kernel((x - float32(j)) / factor) k = f.kernel((x - float32(j)) / factor)
@ -69,7 +68,7 @@ func (f *filterModel) convolution1d(x float32, p []colorArray, factor float32) c
c[i] = c[i] / sum c[i] = c[i] / sum
} }
return c return
} }
func (f *filterModel) Interpolate(u float32, y int) color.RGBA64 { func (f *filterModel) Interpolate(u float32, y int) color.RGBA64 {
@ -77,7 +76,7 @@ func (f *filterModel) Interpolate(u float32, y int) color.RGBA64 {
u -= float32(uf) u -= float32(uf)
for i := range f.tempRow { for i := range f.tempRow {
f.tempRow[i] = f.at(uf+i, y) f.at(uf+i, y, &f.tempRow[i])
} }
c := f.convolution1d(u, f.tempRow, f.factor) c := f.convolution1d(u, f.tempRow, f.factor)