aw/go-resize
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Added MitchellNetravali, changed Lanczos a bit

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This commit is contained in:
jst 2012-09-19 19:32:00 +02:00
parent c980eecff5
commit d0b2b9bc39
2 changed files with 26 additions and 7 deletions
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26
filters.go
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@ -115,16 +115,30 @@ func Bicubic(img image.Image) Filter {
}, make([]rgba16, 4), make([]rgba16, 4)}
}
func MitchellNetravali(img image.Image) Filter {
return &filterModel{img, 4, func(x float32) (y float32) {
absX := float32(math.Abs(float64(x)))
if absX <= 1 {
y = absX*absX*(7*absX-12) + 16.0/3
} else {
y = -(absX - 2) * (absX - 2) / 3 * (7*absX - 8)
}
return
}, make([]rgba16, 4), make([]rgba16, 4)}
}
func lanczosKernel(a uint) func(float32) float32 {
return func(x float32) float32 {
return float32(Sinc(float64(x))) * float32(Sinc(float64(x/float32(a))))
}
}
// Lanczos interpolation (a=2).
func Lanczos2(img image.Image) Filter {
return &filterModel{img, 4, func(x float32) float32 {
return float32(Sinc(float64(x))) * float32(Sinc(float64((x)/float32(2))))
}, make([]rgba16, 4), make([]rgba16, 4)}
return &filterModel{img, 4, lanczosKernel(2), make([]rgba16, 4), make([]rgba16, 4)}
}
// Lanczos interpolation (a=3).
func Lanczos3(img image.Image) Filter {
return &filterModel{img, 6, func(x float32) float32 {
return float32(Sinc(float64(x))) * float32(Sinc(float64((x)/float32(3))))
}, make([]rgba16, 6), make([]rgba16, 6)}
return &filterModel{img, 6, lanczosKernel(3), make([]rgba16, 6), make([]rgba16, 6)}
}

7
resize_test.go
View File

@ -3,12 +3,14 @@ package resize
import (
"image"
"image/color"
"runtime"
"testing"
)
var img = image.NewGray16(image.Rect(0, 0, 3, 3))
func init() {
runtime.GOMAXPROCS(runtime.NumCPU())
img.Set(1, 1, color.White)
}
@ -43,6 +45,9 @@ func Test_ZeroImg(t *testing.T) {
}
func Benchmark_BigResize(b *testing.B) {
m := Resize(1000, 1000, img, Lanczos3)
var m image.Image
for i := 0; i < b.N; i++ {
m = Resize(1000, 1000, img, Lanczos3)
}
m.At(0, 0)
}