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resize
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Changed function signature to include error handling. Filters simplified.

This commit is contained in:
jst 2012-08-08 21:32:51 +02:00
parent d573c463cb
commit 14d51db8b4
3 changed files with 47 additions and 60 deletions
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36
filters.go
View File

@ -64,10 +64,10 @@ func Bilinear(x, y float32, img image.Image) color.RGBA64 {
var row [2]RGBA var row [2]RGBA
var col [2]RGBA var col [2]RGBA
row = [2]RGBA{toRGBA(img.At(xf, yf)), toRGBA(img.At(xf+1, yf))} for i := 0; i < 2; i++ {
col[0] = linearInterp(x, &row) row = [2]RGBA{toRGBA(img.At(xf, yf+i)), toRGBA(img.At(xf+1, yf+i))}
row = [2]RGBA{toRGBA(img.At(xf, yf+1)), toRGBA(img.At(xf+1, yf+1))} col[i] = linearInterp(x, &row)
col[1] = linearInterp(x, &row) }
c := linearInterp(y, &col) c := linearInterp(y, &col)
return color.RGBA64{c[0], c[1], c[2], c[3]} return color.RGBA64{c[0], c[1], c[2], c[3]}
@ -88,14 +88,10 @@ func Bicubic(x, y float32, img image.Image) color.RGBA64 {
var row [4]RGBA var row [4]RGBA
var col [4]RGBA var col [4]RGBA
row = [4]RGBA{toRGBA(img.At(xf-1, yf-1)), toRGBA(img.At(xf, yf-1)), toRGBA(img.At(xf+1, yf-1)), toRGBA(img.At(xf+2, yf-1))} for i := 0; i < 4; i++ {
col[0] = cubicInterp(x, &row) row = [4]RGBA{toRGBA(img.At(xf-1, yf+i-1)), toRGBA(img.At(xf, yf+i-1)), toRGBA(img.At(xf+1, yf+i-1)), toRGBA(img.At(xf+2, yf+i-1))}
row = [4]RGBA{toRGBA(img.At(xf-1, yf)), toRGBA(img.At(xf, yf)), toRGBA(img.At(xf+1, yf)), toRGBA(img.At(xf+2, yf))} col[i] = cubicInterp(x, &row)
col[1] = cubicInterp(x, &row) }
row = [4]RGBA{toRGBA(img.At(xf-1, yf+1)), toRGBA(img.At(xf, yf+1)), toRGBA(img.At(xf+1, yf+1)), toRGBA(img.At(xf+2, yf+1))}
col[2] = cubicInterp(x, &row)
row = [4]RGBA{toRGBA(img.At(xf-1, yf+2)), toRGBA(img.At(xf, yf+2)), toRGBA(img.At(xf+1, yf+2)), toRGBA(img.At(xf+2, yf+2))}
col[3] = cubicInterp(x, &row)
c := cubicInterp(y, &col) c := cubicInterp(y, &col)
return color.RGBA64{c[0], c[1], c[2], c[3]} return color.RGBA64{c[0], c[1], c[2], c[3]}
@ -124,18 +120,10 @@ func Lanczos3(x, y float32, img image.Image) color.RGBA64 {
var row [6]RGBA var row [6]RGBA
var col [6]RGBA var col [6]RGBA
row = [6]RGBA{toRGBA(img.At(xf-2, yf-2)), toRGBA(img.At(xf-1, yf-2)), toRGBA(img.At(xf, yf-2)), toRGBA(img.At(xf+1, yf-2)), toRGBA(img.At(xf+2, yf-2)), toRGBA(img.At(xf+3, yf-2))} for i := 0; i < 6; i++ {
col[0] = lanczos_x(x, &row) row = [6]RGBA{toRGBA(img.At(xf-2, yf+i-2)), toRGBA(img.At(xf-1, yf+i-2)), toRGBA(img.At(xf, yf+i-2)), toRGBA(img.At(xf+1, yf+i-2)), toRGBA(img.At(xf+2, yf+i-2)), toRGBA(img.At(xf+3, yf+i-2))}
row = [6]RGBA{toRGBA(img.At(xf-2, yf-1)), toRGBA(img.At(xf-1, yf-1)), toRGBA(img.At(xf, yf-1)), toRGBA(img.At(xf+1, yf-1)), toRGBA(img.At(xf+2, yf-1)), toRGBA(img.At(xf+3, yf-1))} col[i] = lanczos_x(x, &row)
col[1] = lanczos_x(x, &row) }
row = [6]RGBA{toRGBA(img.At(xf-2, yf)), toRGBA(img.At(xf-1, yf)), toRGBA(img.At(xf, yf)), toRGBA(img.At(xf+1, yf)), toRGBA(img.At(xf+2, yf)), toRGBA(img.At(xf+3, yf))}
col[2] = lanczos_x(x, &row)
row = [6]RGBA{toRGBA(img.At(xf-2, yf+1)), toRGBA(img.At(xf-1, yf+1)), toRGBA(img.At(xf, yf+1)), toRGBA(img.At(xf+1, yf+1)), toRGBA(img.At(xf+2, yf+1)), toRGBA(img.At(xf+3, yf+1))}
col[3] = lanczos_x(x, &row)
row = [6]RGBA{toRGBA(img.At(xf-2, yf+2)), toRGBA(img.At(xf-1, yf+2)), toRGBA(img.At(xf, yf+2)), toRGBA(img.At(xf+1, yf+2)), toRGBA(img.At(xf+2, yf+2)), toRGBA(img.At(xf+3, yf+2))}
col[4] = lanczos_x(x, &row)
row = [6]RGBA{toRGBA(img.At(xf-2, yf+3)), toRGBA(img.At(xf-1, yf+3)), toRGBA(img.At(xf, yf+3)), toRGBA(img.At(xf+1, yf+3)), toRGBA(img.At(xf+2, yf+3)), toRGBA(img.At(xf+3, yf+3))}
col[5] = lanczos_x(x, &row)
c := lanczos_x(y, &col) c := lanczos_x(y, &col)
return color.RGBA64{c[0], c[1], c[2], c[3]} return color.RGBA64{c[0], c[1], c[2], c[3]}

51
resize.go
View File

@ -25,6 +25,7 @@ THIS SOFTWARE.
package resize package resize
import ( import (
"errors"
"image" "image"
"image/color" "image/color"
"runtime" "runtime"
@ -46,28 +47,21 @@ func (t *Trans2) Eval(x, y float32) (u, v float32) {
} }
// Calculate scaling factors using old and new image dimensions. // Calculate scaling factors using old and new image dimensions.
func calcFactors(w, h int, wo, ho float32) (sx, sy float32) { func calcFactors(width, height int, oldWidth, oldHeight float32) (scaleX, scaleY float32) {
if w <= 0 { if width == -1 {
w = -1 if height == -1 {
} scaleX = 1.0
if h <= 0 { scaleY = 1.0
h = -1
}
if w == -1 {
if h == -1 {
sx = 1.0
sy = 1.0
} else { } else {
sy = ho / float32(h) scaleY = oldHeight / float32(height)
sx = sy scaleX = scaleY
} }
} else { } else {
sx = wo / float32(w) scaleX = oldWidth / float32(width)
if h == -1 { if height == -1 {
sy = sx scaleY = scaleX
} else { } else {
sy = ho / float32(h) scaleY = oldHeight / float32(height)
} }
} }
return return
@ -82,15 +76,19 @@ type InterpolationFunction func(float32, float32, image.Image) color.RGBA64
// If one of the parameters w or h is set to -1, its size will be calculated so that // If one of the parameters w or h is set to -1, its size will be calculated so that
// the aspect ratio is that of the originating image. // the aspect ratio is that of the originating image.
// The resizing algorithm uses channels for parallel computation. // The resizing algorithm uses channels for parallel computation.
func Resize(w int, h int, img image.Image, interp InterpolationFunction) image.Image { func Resize(width, height int, img image.Image, interp InterpolationFunction) (out image.Image, err error) {
b_old := img.Bounds() if width < -1 || height < -1 {
w_old := float32(b_old.Dx()) err = errors.New("Wrong width/height argument")
h_old := float32(b_old.Dy()) return
}
oldBounds := img.Bounds()
oldWidth := float32(oldBounds.Dx())
oldHeight := float32(oldBounds.Dy())
scaleX, scaleY := calcFactors(w, h, w_old, h_old) scaleX, scaleY := calcFactors(width, height, oldWidth, oldHeight)
t := Trans2{scaleX, 0, float32(b_old.Min.X), 0, scaleY, float32(b_old.Min.Y)} t := Trans2{scaleX, 0, float32(oldBounds.Min.X), 0, scaleY, float32(oldBounds.Min.Y)}
m := image.NewRGBA64(image.Rect(0, 0, int(w_old/scaleX), int(h_old/scaleY))) m := image.NewRGBA64(image.Rect(0, 0, int(oldWidth/scaleX), int(oldHeight/scaleY)))
b := m.Bounds() b := m.Bounds()
c := make(chan int, NCPU) c := make(chan int, NCPU)
@ -110,6 +108,7 @@ func Resize(w int, h int, img image.Image, interp InterpolationFunction) image.I
for i := 0; i < NCPU; i++ { for i := 0; i < NCPU; i++ {
<-c <-c
} }
out = m
return m return
} }

20
resize_test.go
View File

@ -11,30 +11,30 @@ var img = image.NewGray16(image.Rect(0, 0, 3, 3))
func Test_Nearest(t *testing.T) { func Test_Nearest(t *testing.T) {
img.Set(1, 1, color.White) img.Set(1, 1, color.White)
m := Resize(6, -1, img, NearestNeighbor) m, err := Resize(6, -1, img, NearestNeighbor)
if m.At(2, 2) != m.At(3, 3) { if err != nil || m.At(2, 2) != m.At(3, 3) {
t.Fail() t.Fail()
} }
} }
func Test_Param1(t *testing.T) { func Test_Param1(t *testing.T) {
m := Resize(-1, -1, img, NearestNeighbor) m, err := Resize(-1, -1, img, NearestNeighbor)
if m.Bounds() != img.Bounds() { if err != nil || m.Bounds() != img.Bounds() {
t.Fail() t.Fail()
} }
} }
func Test_Param2(t *testing.T) { func Test_Param2(t *testing.T) {
m := Resize(-100, -1, img, NearestNeighbor) _, err := Resize(-100, -1, img, NearestNeighbor)
if m.Bounds() != img.Bounds() { if err == nil {
t.Fail() t.Fail()
} }
} }
func Test_Param3(t *testing.T) { func Test_Param3(t *testing.T) {
m := Resize(0, -1, img, NearestNeighbor) m, err := Resize(0, -1, img, NearestNeighbor)
if m.Bounds() != img.Bounds() { if err != nil || m.Bounds() != image.Rect(0, 0, 0, 0) {
t.Fail() t.Fail()
} }
} }
@ -42,8 +42,8 @@ func Test_Param3(t *testing.T) {
func Test_ZeroImg(t *testing.T) { func Test_ZeroImg(t *testing.T) {
zeroImg := image.NewGray16(image.Rect(0, 0, 0, 0)) zeroImg := image.NewGray16(image.Rect(0, 0, 0, 0))
m := Resize(-1, -1, zeroImg, NearestNeighbor) m, err := Resize(-1, -1, zeroImg, NearestNeighbor)
if m.Bounds() != zeroImg.Bounds() { if err != nil || m.Bounds() != zeroImg.Bounds() {
t.Fail() t.Fail()
} }
} }