1 files changed, 200 insertions, 0 deletions
diff --git a/vendor/github.com/disintegration/imaging/adjust.go b/vendor/github.com/disintegration/imaging/adjust.go
new file mode 100644
index 000000000..9b1b83a4f
--- /dev/null
+++ b/vendor/github.com/disintegration/imaging/adjust.go
@@ -0,0 +1,200 @@
+package imaging
+
+import (
+	"image"
+	"image/color"
+	"math"
+)
+
+// 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 := toNRGBA(img)
+	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
+				j := y*dst.Stride + x*4
+
+				r := src.Pix[i+0]
+				g := src.Pix[i+1]
+				b := src.Pix[i+2]
+				a := src.Pix[i+3]
+
+				c := fn(color.NRGBA{r, g, b, a})
+
+				dst.Pix[j+0] = c.R
+				dst.Pix[j+1] = c.G
+				dst.Pix[j+2] = c.B
+				dst.Pix[j+3] = c.A
+			}
+		}
+	})
+
+	return dst
+}
+
+// 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)
+	}
+
+	fn := func(c color.NRGBA) color.NRGBA {
+		return color.NRGBA{lut[c.R], lut[c.G], lut[c.B], c.A}
+	}
+
+	return AdjustFunc(img, fn)
+}
+
+func sigmoid(a, b, x float64) float64 {
+	return 1 / (1 + math.Exp(b*(a-x)))
+}
+
+// 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)
+		}
+	}
+
+	fn := func(c color.NRGBA) color.NRGBA {
+		return color.NRGBA{lut[c.R], lut[c.G], lut[c.B], c.A}
+	}
+
+	return AdjustFunc(img, fn)
+}
+
+// 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 grey 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++ {
+		if 0 <= v && v <= 1 {
+			lut[i] = clamp((0.5 + (float64(i)/255.0-0.5)*v) * 255.0)
+		} else if 1 < v && v < 2 {
+			lut[i] = clamp((0.5 + (float64(i)/255.0-0.5)*(1/(2.0-v))) * 255.0)
+		} else {
+			lut[i] = uint8(float64(i)/255.0+0.5) * 255
+		}
+	}
+
+	fn := func(c color.NRGBA) color.NRGBA {
+		return color.NRGBA{lut[c.R], lut[c.G], lut[c.B], c.A}
+	}
+
+	return AdjustFunc(img, fn)
+}
+
+// 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)
+	}
+
+	fn := func(c color.NRGBA) color.NRGBA {
+		return color.NRGBA{lut[c.R], lut[c.G], lut[c.B], c.A}
+	}
+
+	return AdjustFunc(img, fn)
+}
+
+// Grayscale produces grayscale version of the image.
+func Grayscale(img image.Image) *image.NRGBA {
+	fn := func(c color.NRGBA) color.NRGBA {
+		f := 0.299*float64(c.R) + 0.587*float64(c.G) + 0.114*float64(c.B)
+		y := uint8(f + 0.5)
+		return color.NRGBA{y, y, y, c.A}
+	}
+	return AdjustFunc(img, fn)
+}
+
+// Invert produces inverted (negated) version of the image.
+func Invert(img image.Image) *image.NRGBA {
+	fn := func(c color.NRGBA) color.NRGBA {
+		return color.NRGBA{255 - c.R, 255 - c.G, 255 - c.B, c.A}
+	}
+	return AdjustFunc(img, fn)
+}