diff options
Diffstat (limited to 'Godeps/_workspace/src/github.com/nfnt/resize/filters.go')
| -rw-r--r-- | Godeps/_workspace/src/github.com/nfnt/resize/filters.go | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/Godeps/_workspace/src/github.com/nfnt/resize/filters.go b/Godeps/_workspace/src/github.com/nfnt/resize/filters.go new file mode 100644 index 000000000..4ce04e389 --- /dev/null +++ b/Godeps/_workspace/src/github.com/nfnt/resize/filters.go @@ -0,0 +1,143 @@ +/* +Copyright (c) 2012, Jan Schlicht <jan.schlicht@gmail.com> + +Permission to use, copy, modify, and/or distribute this software for any purpose +with or without fee is hereby granted, provided that the above copyright notice +and this permission notice appear in all copies. + +THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH +REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND +FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, +INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS +OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER +TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF +THIS SOFTWARE. +*/ + +package resize + +import ( + "math" +) + +func nearest(in float64) float64 { + if in >= -0.5 && in < 0.5 { + return 1 + } + return 0 +} + +func linear(in float64) float64 { + in = math.Abs(in) + if in <= 1 { + return 1 - in + } + return 0 +} + +func cubic(in float64) float64 { + in = math.Abs(in) + if in <= 1 { + return in*in*(1.5*in-2.5) + 1.0 + } + if in <= 2 { + return in*(in*(2.5-0.5*in)-4.0) + 2.0 + } + return 0 +} + +func mitchellnetravali(in float64) float64 { + in = math.Abs(in) + if in <= 1 { + return (7.0*in*in*in - 12.0*in*in + 5.33333333333) * 0.16666666666 + } + if in <= 2 { + return (-2.33333333333*in*in*in + 12.0*in*in - 20.0*in + 10.6666666667) * 0.16666666666 + } + return 0 +} + +func sinc(x float64) float64 { + x = math.Abs(x) * math.Pi + if x >= 1.220703e-4 { + return math.Sin(x) / x + } + return 1 +} + +func lanczos2(in float64) float64 { + if in > -2 && in < 2 { + return sinc(in) * sinc(in*0.5) + } + return 0 +} + +func lanczos3(in float64) float64 { + if in > -3 && in < 3 { + return sinc(in) * sinc(in*0.3333333333333333) + } + return 0 +} + +// range [-256,256] +func createWeights8(dy, filterLength int, blur, scale float64, kernel func(float64) float64) ([]int16, []int, int) { + filterLength = filterLength * int(math.Max(math.Ceil(blur*scale), 1)) + filterFactor := math.Min(1./(blur*scale), 1) + + coeffs := make([]int16, dy*filterLength) + start := make([]int, dy) + for y := 0; y < dy; y++ { + interpX := scale*(float64(y)+0.5) - 0.5 + start[y] = int(interpX) - filterLength/2 + 1 + interpX -= float64(start[y]) + for i := 0; i < filterLength; i++ { + in := (interpX - float64(i)) * filterFactor + coeffs[y*filterLength+i] = int16(kernel(in) * 256) + } + } + + return coeffs, start, filterLength +} + +// range [-65536,65536] +func createWeights16(dy, filterLength int, blur, scale float64, kernel func(float64) float64) ([]int32, []int, int) { + filterLength = filterLength * int(math.Max(math.Ceil(blur*scale), 1)) + filterFactor := math.Min(1./(blur*scale), 1) + + coeffs := make([]int32, dy*filterLength) + start := make([]int, dy) + for y := 0; y < dy; y++ { + interpX := scale*(float64(y)+0.5) - 0.5 + start[y] = int(interpX) - filterLength/2 + 1 + interpX -= float64(start[y]) + for i := 0; i < filterLength; i++ { + in := (interpX - float64(i)) * filterFactor + coeffs[y*filterLength+i] = int32(kernel(in) * 65536) + } + } + + return coeffs, start, filterLength +} + +func createWeightsNearest(dy, filterLength int, blur, scale float64) ([]bool, []int, int) { + filterLength = filterLength * int(math.Max(math.Ceil(blur*scale), 1)) + filterFactor := math.Min(1./(blur*scale), 1) + + coeffs := make([]bool, dy*filterLength) + start := make([]int, dy) + for y := 0; y < dy; y++ { + interpX := scale*(float64(y)+0.5) - 0.5 + start[y] = int(interpX) - filterLength/2 + 1 + interpX -= float64(start[y]) + for i := 0; i < filterLength; i++ { + in := (interpX - float64(i)) * filterFactor + if in >= -0.5 && in < 0.5 { + coeffs[y*filterLength+i] = true + } else { + coeffs[y*filterLength+i] = false + } + } + } + + return coeffs, start, filterLength +} |