016a61cd31
This is a complete rewrite! The tight scaling loop needs data locality for optimal performance. The old version used lots of pointer redirections to access image data which was bad for data locality. By providing the complete loop for each image type, this problem is solved. Unfortunately this increases code duplication but the result should be worth it: I could measure a ~6x speed-up for certain test cases!
117 lines
3.0 KiB
Go
117 lines
3.0 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, minx, filterLength int, blur, scale float64, kernel func(float64) float64) ([]int16, 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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for y := 0; y < dy; y++ {
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interpX := scale*(float64(y)+0.5) + float64(minx)
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start := int(interpX) - filterLength/2 + 1
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for i := 0; i < filterLength; i++ {
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in := (interpX - float64(start) - 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, filterLength
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}
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// range [-65536,65536]
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func createWeights16(dy, minx, filterLength int, blur, scale float64, kernel func(float64) float64) ([]int32, 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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for y := 0; y < dy; y++ {
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interpX := scale*(float64(y)+0.5) + float64(minx)
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start := int(interpX) - filterLength/2 + 1
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for i := 0; i < filterLength; i++ {
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in := (interpX - float64(start) - 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, filterLength
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}
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