144 lines
3.7 KiB
Go
144 lines
3.7 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 (
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"math"
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)
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func nearest(in float64) float64 {
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if in >= -0.5 && in < 0.5 {
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return 1
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}
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return 0
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}
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func linear(in float64) float64 {
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in = math.Abs(in)
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if in <= 1 {
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return 1 - in
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}
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return 0
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}
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func cubic(in float64) float64 {
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in = math.Abs(in)
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if in <= 1 {
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return in*in*(1.5*in-2.5) + 1.0
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}
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if in <= 2 {
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return in*(in*(2.5-0.5*in)-4.0) + 2.0
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}
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return 0
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}
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func mitchellnetravali(in float64) float64 {
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in = math.Abs(in)
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if in <= 1 {
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return (7.0*in*in*in - 12.0*in*in + 5.33333333333) * 0.16666666666
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}
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if in <= 2 {
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return (-2.33333333333*in*in*in + 12.0*in*in - 20.0*in + 10.6666666667) * 0.16666666666
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}
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return 0
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}
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func sinc(x float64) float64 {
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x = math.Abs(x) * math.Pi
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if x >= 1.220703e-4 {
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return math.Sin(x) / x
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}
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return 1
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}
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func lanczos2(in float64) float64 {
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if in > -2 && in < 2 {
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return sinc(in) * sinc(in*0.5)
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}
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return 0
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}
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func lanczos3(in float64) float64 {
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if in > -3 && in < 3 {
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return sinc(in) * sinc(in*0.3333333333333333)
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}
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return 0
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}
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// range [-256,256]
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func createWeights8(dy, filterLength int, blur, scale float64, kernel func(float64) float64) ([]int16, []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([]int16, 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) - 0.5
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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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coeffs[y*filterLength+i] = int16(kernel(in) * 256)
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}
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}
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return coeffs, start, filterLength
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}
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// range [-65536,65536]
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func createWeights16(dy, filterLength int, blur, scale float64, kernel func(float64) float64) ([]int32, []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([]int32, 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) - 0.5
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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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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, 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) - 0.5
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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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