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authorWim <wim@42.be>2020-12-31 14:48:12 +0100
committerGitHub <noreply@github.com>2020-12-31 14:48:12 +0100
commit4f20ebead36876a88391bf033d1de3e4cf0228da (patch)
tree70b6fd79c6a5e00c958c29a7bd3926f074e76ba6 /vendor/github.com/disintegration/imaging/effects.go
parenta9f89dbc645aafc68daa9fc8d589f55104b535c7 (diff)
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Update vendor for next release (#1343)
Diffstat (limited to 'vendor/github.com/disintegration/imaging/effects.go')
-rw-r--r--vendor/github.com/disintegration/imaging/effects.go169
1 files changed, 169 insertions, 0 deletions
diff --git a/vendor/github.com/disintegration/imaging/effects.go b/vendor/github.com/disintegration/imaging/effects.go
new file mode 100644
index 00000000..47316b70
--- /dev/null
+++ b/vendor/github.com/disintegration/imaging/effects.go
@@ -0,0 +1,169 @@
+package imaging
+
+import (
+ "image"
+ "math"
+)
+
+func gaussianBlurKernel(x, sigma float64) float64 {
+ return math.Exp(-(x*x)/(2*sigma*sigma)) / (sigma * math.Sqrt(2*math.Pi))
+}
+
+// Blur produces a blurred version of the image using a Gaussian function.
+// Sigma parameter must be positive and indicates how much the image will be blurred.
+//
+// Example:
+//
+// dstImage := imaging.Blur(srcImage, 3.5)
+//
+func Blur(img image.Image, sigma float64) *image.NRGBA {
+ if sigma <= 0 {
+ return Clone(img)
+ }
+
+ radius := int(math.Ceil(sigma * 3.0))
+ kernel := make([]float64, radius+1)
+
+ for i := 0; i <= radius; i++ {
+ kernel[i] = gaussianBlurKernel(float64(i), sigma)
+ }
+
+ return blurVertical(blurHorizontal(img, kernel), kernel)
+}
+
+func blurHorizontal(img image.Image, kernel []float64) *image.NRGBA {
+ src := newScanner(img)
+ dst := image.NewNRGBA(image.Rect(0, 0, src.w, src.h))
+ radius := len(kernel) - 1
+
+ parallel(0, src.h, func(ys <-chan int) {
+ scanLine := make([]uint8, src.w*4)
+ scanLineF := make([]float64, len(scanLine))
+ for y := range ys {
+ src.scan(0, y, src.w, y+1, scanLine)
+ for i, v := range scanLine {
+ scanLineF[i] = float64(v)
+ }
+ for x := 0; x < src.w; x++ {
+ min := x - radius
+ if min < 0 {
+ min = 0
+ }
+ max := x + radius
+ if max > src.w-1 {
+ max = src.w - 1
+ }
+ var r, g, b, a, wsum float64
+ for ix := min; ix <= max; ix++ {
+ i := ix * 4
+ weight := kernel[absint(x-ix)]
+ wsum += weight
+ s := scanLineF[i : i+4 : i+4]
+ wa := s[3] * weight
+ r += s[0] * wa
+ g += s[1] * wa
+ b += s[2] * wa
+ a += wa
+ }
+ if a != 0 {
+ aInv := 1 / a
+ j := y*dst.Stride + x*4
+ d := dst.Pix[j : j+4 : j+4]
+ d[0] = clamp(r * aInv)
+ d[1] = clamp(g * aInv)
+ d[2] = clamp(b * aInv)
+ d[3] = clamp(a / wsum)
+ }
+ }
+ }
+ })
+
+ return dst
+}
+
+func blurVertical(img image.Image, kernel []float64) *image.NRGBA {
+ src := newScanner(img)
+ dst := image.NewNRGBA(image.Rect(0, 0, src.w, src.h))
+ radius := len(kernel) - 1
+
+ parallel(0, src.w, func(xs <-chan int) {
+ scanLine := make([]uint8, src.h*4)
+ scanLineF := make([]float64, len(scanLine))
+ for x := range xs {
+ src.scan(x, 0, x+1, src.h, scanLine)
+ for i, v := range scanLine {
+ scanLineF[i] = float64(v)
+ }
+ for y := 0; y < src.h; y++ {
+ min := y - radius
+ if min < 0 {
+ min = 0
+ }
+ max := y + radius
+ if max > src.h-1 {
+ max = src.h - 1
+ }
+ var r, g, b, a, wsum float64
+ for iy := min; iy <= max; iy++ {
+ i := iy * 4
+ weight := kernel[absint(y-iy)]
+ wsum += weight
+ s := scanLineF[i : i+4 : i+4]
+ wa := s[3] * weight
+ r += s[0] * wa
+ g += s[1] * wa
+ b += s[2] * wa
+ a += wa
+ }
+ if a != 0 {
+ aInv := 1 / a
+ j := y*dst.Stride + x*4
+ d := dst.Pix[j : j+4 : j+4]
+ d[0] = clamp(r * aInv)
+ d[1] = clamp(g * aInv)
+ d[2] = clamp(b * aInv)
+ d[3] = clamp(a / wsum)
+ }
+ }
+ }
+ })
+
+ return dst
+}
+
+// Sharpen produces a sharpened version of the image.
+// Sigma parameter must be positive and indicates how much the image will be sharpened.
+//
+// Example:
+//
+// dstImage := imaging.Sharpen(srcImage, 3.5)
+//
+func Sharpen(img image.Image, sigma float64) *image.NRGBA {
+ if sigma <= 0 {
+ return Clone(img)
+ }
+
+ src := newScanner(img)
+ dst := image.NewNRGBA(image.Rect(0, 0, src.w, src.h))
+ blurred := Blur(img, sigma)
+
+ parallel(0, src.h, func(ys <-chan int) {
+ scanLine := make([]uint8, src.w*4)
+ for y := range ys {
+ src.scan(0, y, src.w, y+1, scanLine)
+ j := y * dst.Stride
+ for i := 0; i < src.w*4; i++ {
+ val := int(scanLine[i])<<1 - int(blurred.Pix[j])
+ if val < 0 {
+ val = 0
+ } else if val > 0xff {
+ val = 0xff
+ }
+ dst.Pix[j] = uint8(val)
+ j++
+ }
+ }
+ })
+
+ return dst
+}