mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-12-05 10:02:47 +00:00
254 lines
7.2 KiB
Go
254 lines
7.2 KiB
Go
|
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
|
||
|
}
|