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

View File

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

View File

@ -25,6 +25,7 @@ THIS SOFTWARE.
package resize
import (
"errors"
"image"
"image/color"
"runtime"
@ -46,28 +47,21 @@ func (t *Trans2) Eval(x, y float32) (u, v float32) {
}
// Calculate scaling factors using old and new image dimensions.
func calcFactors(w, h int, wo, ho float32) (sx, sy float32) {
if w <= 0 {
w = -1
}
if h <= 0 {
h = -1
}
if w == -1 {
if h == -1 {
sx = 1.0
sy = 1.0
func calcFactors(width, height int, oldWidth, oldHeight float32) (scaleX, scaleY float32) {
if width == -1 {
if height == -1 {
scaleX = 1.0
scaleY = 1.0
} else {
sy = ho / float32(h)
sx = sy
scaleY = oldHeight / float32(height)
scaleX = scaleY
}
} else {
sx = wo / float32(w)
if h == -1 {
sy = sx
scaleX = oldWidth / float32(width)
if height == -1 {
scaleY = scaleX
} else {
sy = ho / float32(h)
scaleY = oldHeight / float32(height)
}
}
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
// the aspect ratio is that of the originating image.
// The resizing algorithm uses channels for parallel computation.
func Resize(w int, h int, img image.Image, interp InterpolationFunction) image.Image {
b_old := img.Bounds()
w_old := float32(b_old.Dx())
h_old := float32(b_old.Dy())
func Resize(width, height int, img image.Image, interp InterpolationFunction) (out image.Image, err error) {
if width < -1 || height < -1 {
err = errors.New("Wrong width/height argument")
return
}
oldBounds := img.Bounds()
oldWidth := float32(oldBounds.Dx())
oldHeight := float32(oldBounds.Dy())
scaleX, scaleY := calcFactors(w, h, w_old, h_old)
t := Trans2{scaleX, 0, float32(b_old.Min.X), 0, scaleY, float32(b_old.Min.Y)}
scaleX, scaleY := calcFactors(width, height, oldWidth, oldHeight)
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()
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++ {
<-c
}
out = m
return m
return
}

View File

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