Optimized Nearest-Neighbor function - 2x faster
This commit is contained in:
Charlie Vieth
parent
80b3fc2b3f
commit
427b8d133e
29
filters.go
29
filters.go
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@ -89,8 +89,9 @@ func createWeights8(dy, minx, filterLength int, blur, scale float64, kernel func
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for y := 0; y < dy; y++ {
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interpX := scale*(float64(y)+0.5) + float64(minx)
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start[y] = int(interpX) - filterLength/2 + 1
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interpX -= float64(start[y])
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for i := 0; i < filterLength; i++ {
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in := (interpX - float64(start[y]) - float64(i)) * filterFactor
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in := (interpX - float64(i)) * filterFactor
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coeffs[y*filterLength+i] = int16(kernel(in) * 256)
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}
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}
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@ -108,11 +109,35 @@ func createWeights16(dy, minx, filterLength int, blur, scale float64, kernel fun
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for y := 0; y < dy; y++ {
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interpX := scale*(float64(y)+0.5) + float64(minx)
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start[y] = int(interpX) - filterLength/2 + 1
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interpX -= float64(start[y])
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for i := 0; i < filterLength; i++ {
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in := (interpX - float64(start[y]) - float64(i)) * filterFactor
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in := (interpX - float64(i)) * filterFactor
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coeffs[y*filterLength+i] = int32(kernel(in) * 65536)
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}
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}
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return coeffs, start, filterLength
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}
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func createWeightsNearest(dy, minx, filterLength int, blur, scale float64) ([]bool, []int, int) {
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filterLength = filterLength * int(math.Max(math.Ceil(blur*scale), 1))
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filterFactor := math.Min(1./(blur*scale), 1)
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coeffs := make([]bool, dy*filterLength)
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start := make([]int, dy)
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for y := 0; y < dy; y++ {
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interpX := scale*(float64(y)+0.5) + float64(minx)
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start[y] = int(interpX) - filterLength/2 + 1
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interpX -= float64(start[y])
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for i := 0; i < filterLength; i++ {
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in := (interpX - float64(i)) * filterFactor
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if in >= -0.5 && in < 0.5 {
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coeffs[y*filterLength+i] = true
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} else {
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coeffs[y*filterLength+i] = false
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}
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}
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}
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return coeffs, start, filterLength
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}
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228
nearest.go
Normal file
228
nearest.go
Normal file
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@ -0,0 +1,228 @@
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package resize
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import "image"
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func floatToUint8(x float32) uint8 {
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// Nearest-neighbor values are always
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// positive no need to check lower-bound.
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if x > 0xfe {
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return 0xff
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}
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return uint8(x)
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}
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func floatToUint16(x float32) uint16 {
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if x > 0xfffe {
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return 0xffff
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}
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return uint16(x)
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}
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func nearestGeneric(in image.Image, out *image.RGBA64, scale float64, coeffs []bool, offset []int, filterLength int) {
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oldBounds := in.Bounds()
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newBounds := out.Bounds()
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for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
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for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
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var rgba [4]float32
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var sum float32
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start := offset[y]
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ci := (y - newBounds.Min.Y) * filterLength
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for i := 0; i < filterLength; i++ {
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if coeffs[ci+i] {
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xi := start + i
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switch {
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case uint(xi) < uint(oldBounds.Max.X):
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break
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case xi >= oldBounds.Max.X:
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xi = oldBounds.Min.X
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default:
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xi = oldBounds.Max.X - 1
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}
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r, g, b, a := in.At(xi, x).RGBA()
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rgba[0] += float32(r)
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rgba[1] += float32(g)
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rgba[2] += float32(b)
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rgba[3] += float32(a)
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sum++
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}
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}
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offset := (y-newBounds.Min.Y)*out.Stride + (x-newBounds.Min.X)*8
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value := floatToUint16(rgba[0] / sum)
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out.Pix[offset+0] = uint8(value >> 8)
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out.Pix[offset+1] = uint8(value)
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value = floatToUint16(rgba[1] / sum)
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out.Pix[offset+2] = uint8(value >> 8)
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out.Pix[offset+3] = uint8(value)
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value = floatToUint16(rgba[2] / sum)
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out.Pix[offset+4] = uint8(value >> 8)
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out.Pix[offset+5] = uint8(value)
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value = floatToUint16(rgba[3] / sum)
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out.Pix[offset+6] = uint8(value >> 8)
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out.Pix[offset+7] = uint8(value)
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}
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}
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}
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func nearestRGBA(in *image.RGBA, out *image.RGBA, scale float64, coeffs []bool, offset []int, filterLength int) {
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oldBounds := in.Bounds()
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newBounds := out.Bounds()
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minX := oldBounds.Min.X * 4
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maxX := (oldBounds.Max.X - oldBounds.Min.X - 1) * 4
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for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
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row := in.Pix[(x-oldBounds.Min.Y)*in.Stride:]
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for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
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var rgba [4]float32
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var sum float32
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start := offset[y]
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ci := (y - newBounds.Min.Y) * filterLength
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for i := 0; i < filterLength; i++ {
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if coeffs[ci+i] {
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xi := start + i
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switch {
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case uint(xi) < uint(oldBounds.Max.X):
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xi *= 4
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case xi >= oldBounds.Max.X:
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xi = maxX
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default:
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xi = minX
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}
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rgba[0] += float32(row[xi+0])
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rgba[1] += float32(row[xi+1])
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rgba[2] += float32(row[xi+2])
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rgba[3] += float32(row[xi+3])
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sum++
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}
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}
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xo := (y-newBounds.Min.Y)*out.Stride + (x-newBounds.Min.X)*4
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out.Pix[xo+0] = floatToUint8(rgba[0] / sum)
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out.Pix[xo+1] = floatToUint8(rgba[1] / sum)
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out.Pix[xo+2] = floatToUint8(rgba[2] / sum)
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out.Pix[xo+3] = floatToUint8(rgba[3] / sum)
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}
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}
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}
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func nearestRGBA64(in *image.RGBA64, out *image.RGBA64, scale float64, coeffs []bool, offset []int, filterLength int) {
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oldBounds := in.Bounds()
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newBounds := out.Bounds()
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minX := oldBounds.Min.X * 8
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maxX := (oldBounds.Max.X - oldBounds.Min.X - 1) * 8
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for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
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row := in.Pix[(x-oldBounds.Min.Y)*in.Stride:]
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for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
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var rgba [4]float32
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var sum float32
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start := offset[y]
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ci := (y - newBounds.Min.Y) * filterLength
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for i := 0; i < filterLength; i++ {
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if coeffs[ci+i] {
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xi := start + i
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switch {
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case uint(xi) < uint(oldBounds.Max.X):
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xi *= 8
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case xi >= oldBounds.Max.X:
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xi = maxX
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default:
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xi = minX
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}
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rgba[0] += float32(uint16(row[xi+0])<<8 | uint16(row[xi+1]))
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rgba[1] += float32(uint16(row[xi+2])<<8 | uint16(row[xi+3]))
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rgba[2] += float32(uint16(row[xi+4])<<8 | uint16(row[xi+5]))
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rgba[3] += float32(uint16(row[xi+6])<<8 | uint16(row[xi+7]))
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sum++
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}
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}
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xo := (y-newBounds.Min.Y)*out.Stride + (x-newBounds.Min.X)*8
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value := floatToUint16(rgba[0] / sum)
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out.Pix[xo+0] = uint8(value >> 8)
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out.Pix[xo+1] = uint8(value)
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value = floatToUint16(rgba[1] / sum)
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out.Pix[xo+2] = uint8(value >> 8)
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out.Pix[xo+3] = uint8(value)
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value = floatToUint16(rgba[2] / sum)
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out.Pix[xo+4] = uint8(value >> 8)
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out.Pix[xo+5] = uint8(value)
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value = floatToUint16(rgba[3] / sum)
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out.Pix[xo+6] = uint8(value >> 8)
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out.Pix[xo+7] = uint8(value)
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}
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}
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}
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func nearestGray(in *image.Gray, out *image.Gray, scale float64, coeffs []bool, offset []int, filterLength int) {
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oldBounds := in.Bounds()
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newBounds := out.Bounds()
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minX := oldBounds.Min.X
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maxX := (oldBounds.Max.X - oldBounds.Min.X - 1)
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for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
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row := in.Pix[(x-oldBounds.Min.Y)*in.Stride:]
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for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
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var gray float32
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var sum float32
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start := offset[y]
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ci := (y - newBounds.Min.Y) * filterLength
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for i := 0; i < filterLength; i++ {
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if coeffs[ci+i] {
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xi := start + i
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switch {
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case uint(xi) < uint(oldBounds.Max.X):
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break
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case xi >= oldBounds.Max.X:
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xi = maxX
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default:
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xi = minX
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}
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gray += float32(row[xi])
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sum++
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}
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}
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offset := (y-newBounds.Min.Y)*out.Stride + (x - newBounds.Min.X)
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out.Pix[offset] = floatToUint8(gray / sum)
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}
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}
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}
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func nearestGray16(in *image.Gray16, out *image.Gray16, scale float64, coeffs []bool, offset []int, filterLength int) {
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oldBounds := in.Bounds()
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newBounds := out.Bounds()
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minX := oldBounds.Min.X * 2
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maxX := (oldBounds.Max.X - oldBounds.Min.X - 1) * 2
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for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
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row := in.Pix[(x-oldBounds.Min.Y)*in.Stride:]
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for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
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var gray float32
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var sum float32
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start := offset[y]
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ci := (y - newBounds.Min.Y) * filterLength
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for i := 0; i < filterLength; i++ {
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if coeffs[ci+i] {
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xi := start + i
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switch {
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case uint(xi) < uint(oldBounds.Max.X):
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xi *= 2
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case xi >= oldBounds.Max.X:
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xi = maxX
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default:
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xi = minX
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}
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gray += float32(uint16(row[xi+0])<<8 | uint16(row[xi+1]))
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sum++
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}
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}
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offset := (y-newBounds.Min.Y)*out.Stride + (x-newBounds.Min.X)*2
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value := floatToUint16(gray / sum)
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out.Pix[offset+0] = uint8(value >> 8)
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out.Pix[offset+1] = uint8(value)
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}
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}
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}
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41
nearest_test.go
Normal file
41
nearest_test.go
Normal file
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@ -0,0 +1,41 @@
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package resize
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import "testing"
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func Test_FloatToUint8(t *testing.T) {
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var testData = []struct {
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in float32
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expected uint8
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}{
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{0, 0},
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{255, 255},
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{128, 128},
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{1, 1},
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{256, 255},
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}
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for _, test := range testData {
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actual := floatToUint8(test.in)
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if actual != test.expected {
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t.Fail()
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}
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}
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}
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func Test_FloatToUint16(t *testing.T) {
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var testData = []struct {
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in float32
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expected uint16
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}{
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{0, 0},
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{65535, 65535},
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{128, 128},
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{1, 1},
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{65536, 65535},
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}
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for _, test := range testData {
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actual := floatToUint16(test.in)
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if actual != test.expected {
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t.Fail()
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}
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}
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}
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249
resize.go
249
resize.go
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@ -33,36 +33,41 @@ import (
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// An InterpolationFunction provides the parameters that describe an
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// interpolation kernel. It returns the number of samples to take
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// and the kernel function to use for sampling.
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type InterpolationFunction func() (int, func(float64) float64)
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type InterpolationFunction int
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// InterpolationFunction constants
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const (
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// Nearest-neighbor interpolation
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func NearestNeighbor() (int, func(float64) float64) {
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NearestNeighbor InterpolationFunction = iota
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// Bilinear interpolation
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Bilinear
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// Bicubic interpolation (with cubic hermite spline)
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Bicubic
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// Mitchell-Netravali interpolation
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MitchellNetravali
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// Lanczos interpolation (a=2)
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Lanczos2
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// Lanczos interpolation (a=3)
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Lanczos3
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)
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// kernal, returns an InterpolationFunctions taps and kernel.
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func (i InterpolationFunction) kernel() (int, func(float64) float64) {
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switch i {
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case Bilinear:
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return 2, linear
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case Bicubic:
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return 4, cubic
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case MitchellNetravali:
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return 4, mitchellnetravali
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case Lanczos2:
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return 4, lanczos2
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case Lanczos3:
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return 6, lanczos3
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default:
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// Default to NearestNeighbor.
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return 2, nearest
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}
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// Bilinear interpolation
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func Bilinear() (int, func(float64) float64) {
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return 2, linear
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}
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// Bicubic interpolation (with cubic hermite spline)
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func Bicubic() (int, func(float64) float64) {
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return 4, cubic
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}
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// Mitchell-Netravali interpolation
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func MitchellNetravali() (int, func(float64) float64) {
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return 4, mitchellnetravali
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}
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// Lanczos interpolation (a=2)
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func Lanczos2() (int, func(float64) float64) {
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return 4, lanczos2
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}
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// Lanczos interpolation (a=3)
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func Lanczos3() (int, func(float64) float64) {
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return 6, lanczos3
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}
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// values <1 will sharpen the image
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@ -81,8 +86,11 @@ func Resize(width, height uint, img image.Image, interp InterpolationFunction) i
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if height == 0 {
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height = uint(0.7 + float64(img.Bounds().Dy())/scaleY)
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}
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if interp == NearestNeighbor {
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return resizeNearest(width, height, scaleX, scaleY, img, interp)
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}
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taps, kernel := interp()
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taps, kernel := interp.kernel()
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cpus := runtime.NumCPU()
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wg := sync.WaitGroup{}
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@ -269,6 +277,193 @@ func Resize(width, height uint, img image.Image, interp InterpolationFunction) i
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}
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}
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func resizeNearest(width, height uint, scaleX, scaleY float64, img image.Image, interp InterpolationFunction) image.Image {
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taps, _ := interp.kernel()
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cpus := runtime.NumCPU()
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wg := sync.WaitGroup{}
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switch input := img.(type) {
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case *image.RGBA:
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// 8-bit precision
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temp := image.NewRGBA(image.Rect(0, 0, input.Bounds().Dy(), int(width)))
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result := image.NewRGBA(image.Rect(0, 0, int(width), int(height)))
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// horizontal filter, results in transposed temporary image
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coeffs, offset, filterLength := createWeightsNearest(temp.Bounds().Dy(), input.Bounds().Min.X, taps, blur, scaleX)
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wg.Add(cpus)
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for i := 0; i < cpus; i++ {
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slice := makeSlice(temp, i, cpus).(*image.RGBA)
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go func() {
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defer wg.Done()
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nearestRGBA(input, slice, scaleX, coeffs, offset, filterLength)
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}()
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}
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wg.Wait()
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// horizontal filter on transposed image, result is not transposed
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coeffs, offset, filterLength = createWeightsNearest(result.Bounds().Dy(), temp.Bounds().Min.X, taps, blur, scaleY)
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wg.Add(cpus)
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for i := 0; i < cpus; i++ {
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slice := makeSlice(result, i, cpus).(*image.RGBA)
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go func() {
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defer wg.Done()
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nearestRGBA(temp, slice, scaleY, coeffs, offset, filterLength)
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}()
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}
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wg.Wait()
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return result
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case *image.YCbCr:
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// 8-bit precision
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// accessing the YCbCr arrays in a tight loop is slow.
|
||||
// converting the image before filtering will improve performance.
|
||||
inputAsRGBA := convertYCbCrToRGBA(input)
|
||||
temp := image.NewRGBA(image.Rect(0, 0, input.Bounds().Dy(), int(width)))
|
||||
result := image.NewRGBA(image.Rect(0, 0, int(width), int(height)))
|
||||
|
||||
// horizontal filter, results in transposed temporary image
|
||||
coeffs, offset, filterLength := createWeightsNearest(temp.Bounds().Dy(), input.Bounds().Min.X, taps, blur, scaleX)
|
||||
wg.Add(cpus)
|
||||
for i := 0; i < cpus; i++ {
|
||||
slice := makeSlice(temp, i, cpus).(*image.RGBA)
|
||||
go func() {
|
||||
defer wg.Done()
|
||||
nearestRGBA(inputAsRGBA, slice, scaleX, coeffs, offset, filterLength)
|
||||
}()
|
||||
}
|
||||
wg.Wait()
|
||||
|
||||
// horizontal filter on transposed image, result is not transposed
|
||||
coeffs, offset, filterLength = createWeightsNearest(result.Bounds().Dy(), temp.Bounds().Min.X, taps, blur, scaleY)
|
||||
wg.Add(cpus)
|
||||
for i := 0; i < cpus; i++ {
|
||||
slice := makeSlice(result, i, cpus).(*image.RGBA)
|
||||
go func() {
|
||||
defer wg.Done()
|
||||
nearestRGBA(temp, slice, scaleY, coeffs, offset, filterLength)
|
||||
}()
|
||||
}
|
||||
wg.Wait()
|
||||
return result
|
||||
case *image.RGBA64:
|
||||
// 16-bit precision
|
||||
temp := image.NewRGBA64(image.Rect(0, 0, input.Bounds().Dy(), int(width)))
|
||||
result := image.NewRGBA64(image.Rect(0, 0, int(width), int(height)))
|
||||
|
||||
// horizontal filter, results in transposed temporary image
|
||||
coeffs, offset, filterLength := createWeightsNearest(temp.Bounds().Dy(), input.Bounds().Min.X, taps, blur, scaleX)
|
||||
wg.Add(cpus)
|
||||
for i := 0; i < cpus; i++ {
|
||||
slice := makeSlice(temp, i, cpus).(*image.RGBA64)
|
||||
go func() {
|
||||
defer wg.Done()
|
||||
nearestRGBA64(input, slice, scaleX, coeffs, offset, filterLength)
|
||||
}()
|
||||
}
|
||||
wg.Wait()
|
||||
|
||||
// horizontal filter on transposed image, result is not transposed
|
||||
coeffs, offset, filterLength = createWeightsNearest(result.Bounds().Dy(), temp.Bounds().Min.X, taps, blur, scaleY)
|
||||
wg.Add(cpus)
|
||||
for i := 0; i < cpus; i++ {
|
||||
slice := makeSlice(result, i, cpus).(*image.RGBA64)
|
||||
go func() {
|
||||
defer wg.Done()
|
||||
nearestGeneric(temp, slice, scaleY, coeffs, offset, filterLength)
|
||||
}()
|
||||
}
|
||||
wg.Wait()
|
||||
return result
|
||||
case *image.Gray:
|
||||
// 8-bit precision
|
||||
temp := image.NewGray(image.Rect(0, 0, input.Bounds().Dy(), int(width)))
|
||||
result := image.NewGray(image.Rect(0, 0, int(width), int(height)))
|
||||
|
||||
// horizontal filter, results in transposed temporary image
|
||||
coeffs, offset, filterLength := createWeightsNearest(temp.Bounds().Dy(), input.Bounds().Min.X, taps, blur, scaleX)
|
||||
wg.Add(cpus)
|
||||
for i := 0; i < cpus; i++ {
|
||||
slice := makeSlice(temp, i, cpus).(*image.Gray)
|
||||
go func() {
|
||||
defer wg.Done()
|
||||
nearestGray(input, slice, scaleX, coeffs, offset, filterLength)
|
||||
}()
|
||||
}
|
||||
wg.Wait()
|
||||
|
||||
// horizontal filter on transposed image, result is not transposed
|
||||
coeffs, offset, filterLength = createWeightsNearest(result.Bounds().Dy(), temp.Bounds().Min.X, taps, blur, scaleY)
|
||||
wg.Add(cpus)
|
||||
for i := 0; i < cpus; i++ {
|
||||
slice := makeSlice(result, i, cpus).(*image.Gray)
|
||||
go func() {
|
||||
defer wg.Done()
|
||||
nearestGray(temp, slice, scaleY, coeffs, offset, filterLength)
|
||||
}()
|
||||
}
|
||||
wg.Wait()
|
||||
return result
|
||||
case *image.Gray16:
|
||||
// 16-bit precision
|
||||
temp := image.NewGray16(image.Rect(0, 0, input.Bounds().Dy(), int(width)))
|
||||
result := image.NewGray16(image.Rect(0, 0, int(width), int(height)))
|
||||
|
||||
// horizontal filter, results in transposed temporary image
|
||||
coeffs, offset, filterLength := createWeightsNearest(temp.Bounds().Dy(), input.Bounds().Min.X, taps, blur, scaleX)
|
||||
wg.Add(cpus)
|
||||
for i := 0; i < cpus; i++ {
|
||||
slice := makeSlice(temp, i, cpus).(*image.Gray16)
|
||||
go func() {
|
||||
defer wg.Done()
|
||||
nearestGray16(input, slice, scaleX, coeffs, offset, filterLength)
|
||||
}()
|
||||
}
|
||||
wg.Wait()
|
||||
|
||||
// horizontal filter on transposed image, result is not transposed
|
||||
coeffs, offset, filterLength = createWeightsNearest(result.Bounds().Dy(), temp.Bounds().Min.X, taps, blur, scaleY)
|
||||
wg.Add(cpus)
|
||||
for i := 0; i < cpus; i++ {
|
||||
slice := makeSlice(result, i, cpus).(*image.Gray16)
|
||||
go func() {
|
||||
defer wg.Done()
|
||||
nearestGray16(temp, slice, scaleY, coeffs, offset, filterLength)
|
||||
}()
|
||||
}
|
||||
wg.Wait()
|
||||
return result
|
||||
default:
|
||||
// 16-bit precision
|
||||
temp := image.NewRGBA64(image.Rect(0, 0, img.Bounds().Dy(), int(width)))
|
||||
result := image.NewRGBA64(image.Rect(0, 0, int(width), int(height)))
|
||||
|
||||
// horizontal filter, results in transposed temporary image
|
||||
coeffs, offset, filterLength := createWeightsNearest(temp.Bounds().Dy(), img.Bounds().Min.X, taps, blur, scaleX)
|
||||
wg.Add(cpus)
|
||||
for i := 0; i < cpus; i++ {
|
||||
slice := makeSlice(temp, i, cpus).(*image.RGBA64)
|
||||
go func() {
|
||||
defer wg.Done()
|
||||
nearestGeneric(img, slice, scaleX, coeffs, offset, filterLength)
|
||||
}()
|
||||
}
|
||||
wg.Wait()
|
||||
|
||||
// horizontal filter on transposed image, result is not transposed
|
||||
coeffs, offset, filterLength = createWeightsNearest(result.Bounds().Dy(), temp.Bounds().Min.X, taps, blur, scaleY)
|
||||
wg.Add(cpus)
|
||||
for i := 0; i < cpus; i++ {
|
||||
slice := makeSlice(result, i, cpus).(*image.RGBA64)
|
||||
go func() {
|
||||
defer wg.Done()
|
||||
nearestRGBA64(temp, slice, scaleY, coeffs, offset, filterLength)
|
||||
}()
|
||||
}
|
||||
wg.Wait()
|
||||
return result
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
// Calculates scaling factors using old and new image dimensions.
|
||||
func calcFactors(width, height uint, oldWidth, oldHeight float64) (scaleX, scaleY float64) {
|
||||
if width == 0 {
|
||||
|
|
|
|||
Loading…
Reference in New Issue
Block a user