891127d8d1
The alpha pre-multiplication was applied to an aggregate value an not to the color value. This could cause wrong colors for images with an alpha channel. Fixes #47.
439 lines
12 KiB
Go
439 lines
12 KiB
Go
/*
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Copyright (c) 2012, Jan Schlicht <jan.schlicht@gmail.com>
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Permission to use, copy, modify, and/or distribute this software for any purpose
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with or without fee is hereby granted, provided that the above copyright notice
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and this permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
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REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
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FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
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INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
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OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
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TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
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THIS SOFTWARE.
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*/
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package resize
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import "image"
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// Keep value in [0,255] range.
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func clampUint8(in int32) uint8 {
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// casting a negative int to an uint will result in an overflown
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// large uint. this behavior will be exploited here and in other functions
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// to achieve a higher performance.
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if uint32(in) < 256 {
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return uint8(in)
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}
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if in > 255 {
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return 255
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}
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return 0
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}
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// Keep value in [0,65535] range.
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func clampUint16(in int64) uint16 {
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if uint64(in) < 65536 {
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return uint16(in)
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}
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if in > 65535 {
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return 65535
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}
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return 0
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}
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func resizeGeneric(in image.Image, out *image.RGBA64, scale float64, coeffs []int32, offset []int, filterLength int) {
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newBounds := out.Bounds()
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maxX := in.Bounds().Dx() - 1
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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]int64
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var sum int64
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start := offset[y]
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ci := y * filterLength
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for i := 0; i < filterLength; i++ {
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coeff := coeffs[ci+i]
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if coeff != 0 {
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xi := start + i
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switch {
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case xi < 0:
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xi = 0
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case xi >= maxX:
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xi = maxX
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}
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r, g, b, a := in.At(xi+in.Bounds().Min.X, x+in.Bounds().Min.Y).RGBA()
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rgba[0] += int64(coeff) * int64(r)
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rgba[1] += int64(coeff) * int64(g)
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rgba[2] += int64(coeff) * int64(b)
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rgba[3] += int64(coeff) * int64(a)
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sum += int64(coeff)
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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 := clampUint16(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 = clampUint16(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 = clampUint16(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 = clampUint16(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 resizeRGBA(in *image.RGBA, out *image.RGBA, scale float64, coeffs []int16, offset []int, filterLength int) {
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newBounds := out.Bounds()
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maxX := in.Bounds().Dx() - 1
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for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
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row := in.Pix[x*in.Stride:]
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for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
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var rgba [4]int32
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var sum int32
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start := offset[y]
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ci := y * filterLength
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for i := 0; i < filterLength; i++ {
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coeff := coeffs[ci+i]
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if coeff != 0 {
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xi := start + i
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switch {
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case uint(xi) < uint(maxX):
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xi *= 4
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case xi >= maxX:
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xi = 4 * maxX
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default:
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xi = 0
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}
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rgba[0] += int32(coeff) * int32(row[xi+0])
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rgba[1] += int32(coeff) * int32(row[xi+1])
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rgba[2] += int32(coeff) * int32(row[xi+2])
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rgba[3] += int32(coeff) * int32(row[xi+3])
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sum += int32(coeff)
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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] = clampUint8(rgba[0] / sum)
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out.Pix[xo+1] = clampUint8(rgba[1] / sum)
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out.Pix[xo+2] = clampUint8(rgba[2] / sum)
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out.Pix[xo+3] = clampUint8(rgba[3] / sum)
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}
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}
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}
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func resizeNRGBA(in *image.NRGBA, out *image.RGBA, scale float64, coeffs []int16, offset []int, filterLength int) {
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newBounds := out.Bounds()
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maxX := in.Bounds().Dx() - 1
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for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
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row := in.Pix[x*in.Stride:]
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for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
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var rgba [4]int32
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var sum int32
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start := offset[y]
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ci := y * filterLength
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for i := 0; i < filterLength; i++ {
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coeff := coeffs[ci+i]
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if coeff != 0 {
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xi := start + i
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switch {
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case uint(xi) < uint(maxX):
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xi *= 4
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case xi >= maxX:
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xi = 4 * maxX
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default:
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xi = 0
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}
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// Forward alpha-premultiplication
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a := int32(row[xi+3])
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r := int32(row[xi+0]) * a
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r /= 0xff
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g := int32(row[xi+1]) * a
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g /= 0xff
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b := int32(row[xi+2]) * a
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b /= 0xff
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rgba[0] += int32(coeff) * r
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rgba[1] += int32(coeff) * g
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rgba[2] += int32(coeff) * b
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rgba[3] += int32(coeff) * a
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sum += int32(coeff)
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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] = clampUint8(rgba[0] / sum)
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out.Pix[xo+1] = clampUint8(rgba[1] / sum)
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out.Pix[xo+2] = clampUint8(rgba[2] / sum)
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out.Pix[xo+3] = clampUint8(rgba[3] / sum)
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}
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}
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}
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func resizeRGBA64(in *image.RGBA64, out *image.RGBA64, scale float64, coeffs []int32, offset []int, filterLength int) {
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newBounds := out.Bounds()
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maxX := in.Bounds().Dx() - 1
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for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
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row := in.Pix[x*in.Stride:]
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for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
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var rgba [4]int64
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var sum int64
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start := offset[y]
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ci := y * filterLength
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for i := 0; i < filterLength; i++ {
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coeff := coeffs[ci+i]
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if coeff != 0 {
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xi := start + i
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switch {
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case uint(xi) < uint(maxX):
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xi *= 8
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case xi >= maxX:
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xi = 8 * maxX
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default:
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xi = 0
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}
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rgba[0] += int64(coeff) * (int64(row[xi+0])<<8 | int64(row[xi+1]))
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rgba[1] += int64(coeff) * (int64(row[xi+2])<<8 | int64(row[xi+3]))
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rgba[2] += int64(coeff) * (int64(row[xi+4])<<8 | int64(row[xi+5]))
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rgba[3] += int64(coeff) * (int64(row[xi+6])<<8 | int64(row[xi+7]))
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sum += int64(coeff)
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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 := clampUint16(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 = clampUint16(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 = clampUint16(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 = clampUint16(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 resizeNRGBA64(in *image.NRGBA64, out *image.RGBA64, scale float64, coeffs []int32, offset []int, filterLength int) {
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newBounds := out.Bounds()
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maxX := in.Bounds().Dx() - 1
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for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
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row := in.Pix[x*in.Stride:]
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for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
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var rgba [4]int64
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var sum int64
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start := offset[y]
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ci := y * filterLength
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for i := 0; i < filterLength; i++ {
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coeff := coeffs[ci+i]
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if coeff != 0 {
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xi := start + i
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switch {
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case uint(xi) < uint(maxX):
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xi *= 8
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case xi >= maxX:
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xi = 8 * maxX
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default:
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xi = 0
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}
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// Forward alpha-premultiplication
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a := int64(uint16(row[xi+6])<<8 | uint16(row[xi+7]))
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r := int64(uint16(row[xi+0])<<8|uint16(row[xi+1])) * a
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r /= 0xffff
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g := int64(uint16(row[xi+2])<<8|uint16(row[xi+3])) * a
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g /= 0xffff
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b := int64(uint16(row[xi+4])<<8|uint16(row[xi+5])) * a
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b /= 0xffff
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rgba[0] += int64(coeff) * r
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rgba[1] += int64(coeff) * g
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rgba[2] += int64(coeff) * b
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rgba[3] += int64(coeff) * a
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sum += int64(coeff)
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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 := clampUint16(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 = clampUint16(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 = clampUint16(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 = clampUint16(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 resizeGray(in *image.Gray, out *image.Gray, scale float64, coeffs []int16, offset []int, filterLength int) {
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newBounds := out.Bounds()
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maxX := in.Bounds().Dx() - 1
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for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
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row := in.Pix[(x-newBounds.Min.X)*in.Stride:]
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for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
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var gray int32
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var sum int32
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start := offset[y]
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ci := y * filterLength
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for i := 0; i < filterLength; i++ {
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coeff := coeffs[ci+i]
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if coeff != 0 {
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xi := start + i
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switch {
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case xi < 0:
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xi = 0
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case xi >= maxX:
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xi = maxX
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}
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gray += int32(coeff) * int32(row[xi])
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sum += int32(coeff)
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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] = clampUint8(gray / sum)
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}
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}
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}
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func resizeGray16(in *image.Gray16, out *image.Gray16, scale float64, coeffs []int32, offset []int, filterLength int) {
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newBounds := out.Bounds()
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maxX := in.Bounds().Dx() - 1
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for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
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row := in.Pix[x*in.Stride:]
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for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
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var gray int64
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var sum int64
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start := offset[y]
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ci := y * filterLength
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for i := 0; i < filterLength; i++ {
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coeff := coeffs[ci+i]
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if coeff != 0 {
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xi := start + i
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switch {
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case uint(xi) < uint(maxX):
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xi *= 2
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case xi >= maxX:
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xi = 2 * maxX
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default:
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xi = 0
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}
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gray += int64(coeff) * int64(uint16(row[xi+0])<<8|uint16(row[xi+1]))
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sum += int64(coeff)
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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 := clampUint16(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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func resizeYCbCr(in *ycc, out *ycc, scale float64, coeffs []int16, offset []int, filterLength int) {
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newBounds := out.Bounds()
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maxX := in.Bounds().Dx() - 1
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for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
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row := in.Pix[x*in.Stride:]
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for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
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var p [3]int32
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var sum int32
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start := offset[y]
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ci := y * filterLength
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for i := 0; i < filterLength; i++ {
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coeff := coeffs[ci+i]
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if coeff != 0 {
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xi := start + i
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switch {
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case uint(xi) < uint(maxX):
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xi *= 3
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case xi >= maxX:
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xi = 3 * maxX
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default:
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xi = 0
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}
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p[0] += int32(coeff) * int32(row[xi+0])
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p[1] += int32(coeff) * int32(row[xi+1])
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p[2] += int32(coeff) * int32(row[xi+2])
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sum += int32(coeff)
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}
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}
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xo := (y-newBounds.Min.Y)*out.Stride + (x-newBounds.Min.X)*3
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out.Pix[xo+0] = clampUint8(p[0] / sum)
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out.Pix[xo+1] = clampUint8(p[1] / sum)
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out.Pix[xo+2] = clampUint8(p[2] / sum)
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}
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}
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}
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func nearestYCbCr(in *ycc, out *ycc, scale float64, coeffs []bool, offset []int, filterLength int) {
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newBounds := out.Bounds()
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maxX := in.Bounds().Dx() - 1
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for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
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row := in.Pix[x*in.Stride:]
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for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
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var p [3]float32
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var sum float32
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start := offset[y]
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ci := 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(maxX):
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xi *= 3
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case xi >= maxX:
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xi = 3 * maxX
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default:
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xi = 0
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}
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p[0] += float32(row[xi+0])
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p[1] += float32(row[xi+1])
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p[2] += float32(row[xi+2])
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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)*3
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out.Pix[xo+0] = floatToUint8(p[0] / sum)
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out.Pix[xo+1] = floatToUint8(p[1] / sum)
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out.Pix[xo+2] = floatToUint8(p[2] / sum)
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}
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}
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}
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