gtsocial-umbx

adjust.go (7414B)

---

 package imaging
 
 import (
 	"image"
 	"image/color"
 	"math"
 )
 
 // Grayscale produces a grayscale version of the image.
 func Grayscale(img image.Image) *image.NRGBA {
 	src := newScanner(img)
 	dst := image.NewNRGBA(image.Rect(0, 0, src.w, src.h))
 	parallel(0, src.h, func(ys <-chan int) {
 		for y := range ys {
 			i := y * dst.Stride
 			src.scan(0, y, src.w, y+1, dst.Pix[i:i+src.w*4])
 			for x := 0; x < src.w; x++ {
 				d := dst.Pix[i : i+3 : i+3]
 				r := d[0]
 				g := d[1]
 				b := d[2]
 				f := 0.299*float64(r) + 0.587*float64(g) + 0.114*float64(b)
 				y := uint8(f + 0.5)
 				d[0] = y
 				d[1] = y
 				d[2] = y
 				i += 4
 			}
 		}
 	})
 	return dst
 }
 
 // Invert produces an inverted (negated) version of the image.
 func Invert(img image.Image) *image.NRGBA {
 	src := newScanner(img)
 	dst := image.NewNRGBA(image.Rect(0, 0, src.w, src.h))
 	parallel(0, src.h, func(ys <-chan int) {
 		for y := range ys {
 			i := y * dst.Stride
 			src.scan(0, y, src.w, y+1, dst.Pix[i:i+src.w*4])
 			for x := 0; x < src.w; x++ {
 				d := dst.Pix[i : i+3 : i+3]
 				d[0] = 255 - d[0]
 				d[1] = 255 - d[1]
 				d[2] = 255 - d[2]
 				i += 4
 			}
 		}
 	})
 	return dst
 }
 
 // AdjustSaturation changes the saturation of the image using the percentage parameter and returns the adjusted image.
 // The percentage must be in the range (-100, 100).
 // The percentage = 0 gives the original image.
 // The percentage = 100 gives the image with the saturation value doubled for each pixel.
 // The percentage = -100 gives the image with the saturation value zeroed for each pixel (grayscale).
 //
 // Examples:
 //  dstImage = imaging.AdjustSaturation(srcImage, 25) // Increase image saturation by 25%.
 //  dstImage = imaging.AdjustSaturation(srcImage, -10) // Decrease image saturation by 10%.
 //
 func AdjustSaturation(img image.Image, percentage float64) *image.NRGBA {
 	percentage = math.Min(math.Max(percentage, -100), 100)
 	multiplier := 1 + percentage/100
 
 	return AdjustFunc(img, func(c color.NRGBA) color.NRGBA {
 		h, s, l := rgbToHSL(c.R, c.G, c.B)
 		s *= multiplier
 		if s > 1 {
 			s = 1
 		}
 		r, g, b := hslToRGB(h, s, l)
 		return color.NRGBA{r, g, b, c.A}
 	})
 }
 
 // AdjustContrast changes the contrast of the image using the percentage parameter and returns the adjusted image.
 // The percentage must be in range (-100, 100). The percentage = 0 gives the original image.
 // The percentage = -100 gives solid gray image.
 //
 // Examples:
 //
 //	dstImage = imaging.AdjustContrast(srcImage, -10) // Decrease image contrast by 10%.
 //	dstImage = imaging.AdjustContrast(srcImage, 20) // Increase image contrast by 20%.
 //
 func AdjustContrast(img image.Image, percentage float64) *image.NRGBA {
 	percentage = math.Min(math.Max(percentage, -100.0), 100.0)
 	lut := make([]uint8, 256)
 
 	v := (100.0 + percentage) / 100.0
 	for i := 0; i < 256; i++ {
 		switch {
 		case 0 <= v && v <= 1:
 			lut[i] = clamp((0.5 + (float64(i)/255.0-0.5)*v) * 255.0)
 		case 1 < v && v < 2:
 			lut[i] = clamp((0.5 + (float64(i)/255.0-0.5)*(1/(2.0-v))) * 255.0)
 		default:
 			lut[i] = uint8(float64(i)/255.0+0.5) * 255
 		}
 	}
 
 	return adjustLUT(img, lut)
 }
 
 // AdjustBrightness changes the brightness of the image using the percentage parameter and returns the adjusted image.
 // The percentage must be in range (-100, 100). The percentage = 0 gives the original image.
 // The percentage = -100 gives solid black image. The percentage = 100 gives solid white image.
 //
 // Examples:
 //
 //	dstImage = imaging.AdjustBrightness(srcImage, -15) // Decrease image brightness by 15%.
 //	dstImage = imaging.AdjustBrightness(srcImage, 10) // Increase image brightness by 10%.
 //
 func AdjustBrightness(img image.Image, percentage float64) *image.NRGBA {
 	percentage = math.Min(math.Max(percentage, -100.0), 100.0)
 	lut := make([]uint8, 256)
 
 	shift := 255.0 * percentage / 100.0
 	for i := 0; i < 256; i++ {
 		lut[i] = clamp(float64(i) + shift)
 	}
 
 	return adjustLUT(img, lut)
 }
 
 // AdjustGamma performs a gamma correction on the image and returns the adjusted image.
 // Gamma parameter must be positive. Gamma = 1.0 gives the original image.
 // Gamma less than 1.0 darkens the image and gamma greater than 1.0 lightens it.
 //
 // Example:
 //
 //	dstImage = imaging.AdjustGamma(srcImage, 0.7)
 //
 func AdjustGamma(img image.Image, gamma float64) *image.NRGBA {
 	e := 1.0 / math.Max(gamma, 0.0001)
 	lut := make([]uint8, 256)
 
 	for i := 0; i < 256; i++ {
 		lut[i] = clamp(math.Pow(float64(i)/255.0, e) * 255.0)
 	}
 
 	return adjustLUT(img, lut)
 }
 
 // AdjustSigmoid changes the contrast of the image using a sigmoidal function and returns the adjusted image.
 // It's a non-linear contrast change useful for photo adjustments as it preserves highlight and shadow detail.
 // The midpoint parameter is the midpoint of contrast that must be between 0 and 1, typically 0.5.
 // The factor parameter indicates how much to increase or decrease the contrast, typically in range (-10, 10).
 // If the factor parameter is positive the image contrast is increased otherwise the contrast is decreased.
 //
 // Examples:
 //
 //	dstImage = imaging.AdjustSigmoid(srcImage, 0.5, 3.0) // Increase the contrast.
 //	dstImage = imaging.AdjustSigmoid(srcImage, 0.5, -3.0) // Decrease the contrast.
 //
 func AdjustSigmoid(img image.Image, midpoint, factor float64) *image.NRGBA {
 	if factor == 0 {
 		return Clone(img)
 	}
 
 	lut := make([]uint8, 256)
 	a := math.Min(math.Max(midpoint, 0.0), 1.0)
 	b := math.Abs(factor)
 	sig0 := sigmoid(a, b, 0)
 	sig1 := sigmoid(a, b, 1)
 	e := 1.0e-6
 
 	if factor > 0 {
 		for i := 0; i < 256; i++ {
 			x := float64(i) / 255.0
 			sigX := sigmoid(a, b, x)
 			f := (sigX - sig0) / (sig1 - sig0)
 			lut[i] = clamp(f * 255.0)
 		}
 	} else {
 		for i := 0; i < 256; i++ {
 			x := float64(i) / 255.0
 			arg := math.Min(math.Max((sig1-sig0)*x+sig0, e), 1.0-e)
 			f := a - math.Log(1.0/arg-1.0)/b
 			lut[i] = clamp(f * 255.0)
 		}
 	}
 
 	return adjustLUT(img, lut)
 }
 
 func sigmoid(a, b, x float64) float64 {
 	return 1 / (1 + math.Exp(b*(a-x)))
 }
 
 // adjustLUT applies the given lookup table to the colors of the image.
 func adjustLUT(img image.Image, lut []uint8) *image.NRGBA {
 	src := newScanner(img)
 	dst := image.NewNRGBA(image.Rect(0, 0, src.w, src.h))
 	lut = lut[0:256]
 	parallel(0, src.h, func(ys <-chan int) {
 		for y := range ys {
 			i := y * dst.Stride
 			src.scan(0, y, src.w, y+1, dst.Pix[i:i+src.w*4])
 			for x := 0; x < src.w; x++ {
 				d := dst.Pix[i : i+3 : i+3]
 				d[0] = lut[d[0]]
 				d[1] = lut[d[1]]
 				d[2] = lut[d[2]]
 				i += 4
 			}
 		}
 	})
 	return dst
 }
 
 // AdjustFunc applies the fn function to each pixel of the img image and returns the adjusted image.
 //
 // Example:
 //
 //	dstImage = imaging.AdjustFunc(
 //		srcImage,
 //		func(c color.NRGBA) color.NRGBA {
 //			// Shift the red channel by 16.
 //			r := int(c.R) + 16
 //			if r > 255 {
 //				r = 255
 //			}
 //			return color.NRGBA{uint8(r), c.G, c.B, c.A}
 //		}
 //	)
 //
 func AdjustFunc(img image.Image, fn func(c color.NRGBA) color.NRGBA) *image.NRGBA {
 	src := newScanner(img)
 	dst := image.NewNRGBA(image.Rect(0, 0, src.w, src.h))
 	parallel(0, src.h, func(ys <-chan int) {
 		for y := range ys {
 			i := y * dst.Stride
 			src.scan(0, y, src.w, y+1, dst.Pix[i:i+src.w*4])
 			for x := 0; x < src.w; x++ {
 				d := dst.Pix[i : i+4 : i+4]
 				r := d[0]
 				g := d[1]
 				b := d[2]
 				a := d[3]
 				c := fn(color.NRGBA{r, g, b, a})
 				d[0] = c.R
 				d[1] = c.G
 				d[2] = c.B
 				d[3] = c.A
 				i += 4
 			}
 		}
 	})
 	return dst
 }