aw/go-resize
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Casting float to int has the same properties as math.Floor

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This commit is contained in:
jst 2012-09-04 22:51:19 +02:00
parent d93161631c
commit 524fd851ea
1 changed files with 9 additions and 10 deletions
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19
filters.go
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@ -19,7 +19,6 @@ package resize
import ( import (
"image" "image"
"image/color" "image/color"
"math"
) )
// color.RGBA64 as array // color.RGBA64 as array
@ -44,14 +43,14 @@ func clampToUint16(x float32) (y uint16) {
// Nearest-neighbor interpolation. // Nearest-neighbor interpolation.
// Approximates a value by returning the value of the nearest point. // Approximates a value by returning the value of the nearest point.
func NearestNeighbor(x, y float32, img image.Image) color.RGBA64 { func NearestNeighbor(x, y float32, img image.Image) color.RGBA64 {
xn, yn := int(x), int(y) xn, yn := int(float32(int(x))+0.5), int(float32(int(y))+0.5)
c := toRGBA(img.At(xn, yn)) c := toRGBA(img.At(xn, yn))
return color.RGBA64{c[0], c[1], c[2], c[3]} return color.RGBA64{c[0], c[1], c[2], c[3]}
} }
// Linear interpolation. // Linear interpolation.
func linearInterp(x float32, p *[2]RGBA) (c RGBA) { func linearInterp(x float32, p *[2]RGBA) (c RGBA) {
x -= float32(math.Floor(float64(x))) x -= float32(int(x))
for i := range c { for i := range c {
c[i] = clampToUint16(float32(p[0][i])*(1.0-x) + x*float32(p[1][i])) c[i] = clampToUint16(float32(p[0][i])*(1.0-x) + x*float32(p[1][i]))
} }
@ -60,7 +59,7 @@ func linearInterp(x float32, p *[2]RGBA) (c RGBA) {
// Bilinear interpolation. // Bilinear interpolation.
func Bilinear(x, y float32, img image.Image) color.RGBA64 { func Bilinear(x, y float32, img image.Image) color.RGBA64 {
xf, yf := int(math.Floor(float64(x))), int(math.Floor(float64(y))) xf, yf := int(x), int(y)
var row [2]RGBA var row [2]RGBA
var col [2]RGBA var col [2]RGBA
@ -75,7 +74,7 @@ func Bilinear(x, y float32, img image.Image) color.RGBA64 {
// cubic interpolation // cubic interpolation
func cubicInterp(x float32, p *[4]RGBA) (c RGBA) { func cubicInterp(x float32, p *[4]RGBA) (c RGBA) {
x -= float32(math.Floor(float64(x))) x -= float32(int(x))
for i := range c { for i := range c {
c[i] = clampToUint16(float32(p[1][i]) + 0.5*x*(float32(p[2][i])-float32(p[0][i])+x*(2.0*float32(p[0][i])-5.0*float32(p[1][i])+4.0*float32(p[2][i])-float32(p[3][i])+x*(3.0*(float32(p[1][i])-float32(p[2][i]))+float32(p[3][i])-float32(p[0][i]))))) c[i] = clampToUint16(float32(p[1][i]) + 0.5*x*(float32(p[2][i])-float32(p[0][i])+x*(2.0*float32(p[0][i])-5.0*float32(p[1][i])+4.0*float32(p[2][i])-float32(p[3][i])+x*(3.0*(float32(p[1][i])-float32(p[2][i]))+float32(p[3][i])-float32(p[0][i])))))
} }
@ -84,7 +83,7 @@ func cubicInterp(x float32, p *[4]RGBA) (c RGBA) {
// Bicubic interpolation. // Bicubic interpolation.
func Bicubic(x, y float32, img image.Image) color.RGBA64 { func Bicubic(x, y float32, img image.Image) color.RGBA64 {
xf, yf := int(math.Floor(float64(x))), int(math.Floor(float64(y))) xf, yf := int(x), int(y)
var row [4]RGBA var row [4]RGBA
var col [4]RGBA var col [4]RGBA
@ -99,7 +98,7 @@ func Bicubic(x, y float32, img image.Image) color.RGBA64 {
// 1-d convolution with windowed sinc for a=2. // 1-d convolution with windowed sinc for a=2.
func lanczos2_x(x float32, p *[4]RGBA) (c RGBA) { func lanczos2_x(x float32, p *[4]RGBA) (c RGBA) {
x -= float32(math.Floor(float64(x))) x -= float32(int(x))
var kernel float32 var kernel float32
var sum float32 = 0 // for kernel normalization var sum float32 = 0 // for kernel normalization
@ -120,7 +119,7 @@ func lanczos2_x(x float32, p *[4]RGBA) (c RGBA) {
// Lanczos interpolation (a=2). // Lanczos interpolation (a=2).
func Lanczos2(x, y float32, img image.Image) color.RGBA64 { func Lanczos2(x, y float32, img image.Image) color.RGBA64 {
xf, yf := int(math.Floor(float64(x))), int(math.Floor(float64(y))) xf, yf := int(x), int(y)
var row [4]RGBA var row [4]RGBA
var col [4]RGBA var col [4]RGBA
@ -135,7 +134,7 @@ func Lanczos2(x, y float32, img image.Image) color.RGBA64 {
// 1-d convolution with windowed sinc for a=3. // 1-d convolution with windowed sinc for a=3.
func lanczos3_x(x float32, p *[6]RGBA) (c RGBA) { func lanczos3_x(x float32, p *[6]RGBA) (c RGBA) {
x -= float32(math.Floor(float64(x))) x -= float32(int(x))
var kernel float32 var kernel float32
var sum float32 = 0 // for kernel normalization var sum float32 = 0 // for kernel normalization
@ -156,7 +155,7 @@ func lanczos3_x(x float32, p *[6]RGBA) (c RGBA) {
// Lanczos interpolation (a=3). // Lanczos interpolation (a=3).
func Lanczos3(x, y float32, img image.Image) color.RGBA64 { func Lanczos3(x, y float32, img image.Image) color.RGBA64 {
xf, yf := int(math.Floor(float64(x))), int(math.Floor(float64(y))) xf, yf := int(x), int(y)
var row [6]RGBA var row [6]RGBA
var col [6]RGBA var col [6]RGBA