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sharpen.go
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/
sharpen.go
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package imaging
import (
"image"
)
// Sharpen produces a sharpened version of the image.
// Sigma parameter must be positive and indicates how much the image will be sharpened.
//
// Usage example:
//
// dstImage := imaging.Sharpen(srcImage, 3.5)
//
func Sharpen(img image.Image, sigma float64) *image.NRGBA {
if sigma <= 0 {
// sigma parameter must be positive!
return Clone(img)
}
src := toNRGBA(img)
blurred := Blur(img, sigma, 3)
width := src.Bounds().Max.X
height := src.Bounds().Max.Y
dst := image.NewNRGBA(image.Rect(0, 0, width, height))
parallel(height, func(partStart, partEnd int) {
for y := partStart; y < partEnd; y++ {
for x := 0; x < width; x++ {
i := y*src.Stride + x*4
for j := 0; j < 4; j++ {
k := i + j
val := int(src.Pix[k]) + (int(src.Pix[k]) - int(blurred.Pix[k]))
if val < 0 {
val = 0
} else if val > 255 {
val = 255
}
dst.Pix[k] = uint8(val)
}
}
}
})
return dst
}