aw/go-resize
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Small simplification

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This commit is contained in:
jst 2012-09-16 09:20:11 +02:00
parent c2daecb43a
commit c980eecff5
1 changed files with 9 additions and 11 deletions
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20
filters.go
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@ -25,8 +25,8 @@ import (
// color.RGBA64 as array // color.RGBA64 as array
type rgba16 [4]uint16 type rgba16 [4]uint16
// build RGBA from an arbitrary color // build rgba16 from an arbitrary color
func toRGBA(c color.Color) rgba16 { func toRgba16(c color.Color) rgba16 {
r, g, b, a := c.RGBA() r, g, b, a := c.RGBA()
return rgba16{uint16(r), uint16(g), uint16(b), uint16(a)} return rgba16{uint16(r), uint16(g), uint16(b), uint16(a)}
} }
@ -50,15 +50,12 @@ type filterModel struct {
} }
func (f *filterModel) convolution1d(x float32, p []rgba16) (c rgba16) { func (f *filterModel) convolution1d(x float32, p []rgba16) (c rgba16) {
x -= float32(int(x))
m := float32(f.size/2 - 1)
var k float32 var k float32
var sum float32 = 0 var sum float32 = 0
l := [4]float32{0.0, 0.0, 0.0, 0.0} l := [4]float32{0.0, 0.0, 0.0, 0.0}
for j := range p { for j := range p {
k = f.kernel(x + m - float32(j)) k = f.kernel(x - float32(j))
sum += k sum += k
for i := range c { for i := range c {
l[i] += float32(p[j][i]) * k l[i] += float32(p[j][i]) * k
@ -72,10 +69,12 @@ func (f *filterModel) convolution1d(x float32, p []rgba16) (c rgba16) {
func (f *filterModel) Interpolate(x, y float32) color.RGBA64 { func (f *filterModel) Interpolate(x, y float32) color.RGBA64 {
xf, yf := int(x)-f.size/2+1, int(y)-f.size/2+1 xf, yf := int(x)-f.size/2+1, int(y)-f.size/2+1
x -= float32(xf)
y -= float32(yf)
for i := 0; i < f.size; i++ { for i := 0; i < f.size; i++ {
for j := 0; j < f.size; j++ { for j := 0; j < f.size; j++ {
f.tempRow[j] = toRGBA(f.src.At(xf+j, yf+i)) f.tempRow[j] = toRgba16(f.src.At(xf+j, yf+i))
} }
f.tempCol[i] = f.convolution1d(x, f.tempRow) f.tempCol[i] = f.convolution1d(x, f.tempRow)
} }
@ -84,8 +83,7 @@ func (f *filterModel) Interpolate(x, y float32) color.RGBA64 {
return color.RGBA64{c[0], c[1], c[2], c[3]} return color.RGBA64{c[0], c[1], c[2], c[3]}
} }
// Nearest-neighbor interpolation. // Nearest-neighbor interpolation
// Approximates a value by returning the value of the nearest point.
func NearestNeighbor(img image.Image) Filter { func NearestNeighbor(img image.Image) Filter {
return &filterModel{img, 2, func(x float32) (y float32) { return &filterModel{img, 2, func(x float32) (y float32) {
if x >= -0.5 && x < 0.5 { if x >= -0.5 && x < 0.5 {
@ -97,14 +95,14 @@ func NearestNeighbor(img image.Image) Filter {
}, make([]rgba16, 2), make([]rgba16, 2)} }, make([]rgba16, 2), make([]rgba16, 2)}
} }
// Bicubic interpolation // Bilinear interpolation
func Bilinear(img image.Image) Filter { func Bilinear(img image.Image) Filter {
return &filterModel{img, 2, func(x float32) float32 { return &filterModel{img, 2, func(x float32) float32 {
return 1 - float32(math.Abs(float64(x))) return 1 - float32(math.Abs(float64(x)))
}, make([]rgba16, 2), make([]rgba16, 2)} }, make([]rgba16, 2), make([]rgba16, 2)}
} }
// Bicubic interpolation // Bicubic interpolation (with cubic hermite spline)
func Bicubic(img image.Image) Filter { func Bicubic(img image.Image) Filter {
return &filterModel{img, 4, func(x float32) (y float32) { return &filterModel{img, 4, func(x float32) (y float32) {
absX := float32(math.Abs(float64(x))) absX := float32(math.Abs(float64(x)))