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