mirror of
https://github.com/nxshock/colorcrop.git
synced 2025-07-02 00:23:44 +05:00
77 lines
1.7 KiB
Go
77 lines
1.7 KiB
Go
package colorcrop
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import (
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"image/color"
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"math"
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)
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// colorToXYZ returns CIE XYZ representation of color.
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// https://en.wikipedia.org/wiki/Color_model#CIE_XYZ_color_space
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func colorToXYZ(color color.Color) (x, y, z float64) {
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r, g, b, _ := color.RGBA()
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varR := float64(r>>8) / 255
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varG := float64(g>>8) / 255
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varB := float64(b>>8) / 255
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if varR > 0.04045 {
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varR = math.Pow((varR+0.055)/1.055, 2.4)
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} else {
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varR = varR / 12.92
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}
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if varG > 0.04045 {
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varG = math.Pow((varG+0.055)/1.055, 2.4)
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} else {
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varG = varG / 12.92
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}
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if varB > 0.04045 {
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varB = math.Pow((varB+0.055)/1.055, 2.4)
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} else {
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varB = varB / 12.92
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}
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x = varR*41.24 + varG*35.76 + varB*18.05
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y = varR*21.26 + varG*71.52 + varB*7.22
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z = varR*1.93 + varG*11.92 + varB*95.05
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return x, y, z
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}
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// xyztoLAB converts CIE XYZ color space to CIE LAB color space
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// https://en.wikipedia.org/wiki/Lab_color_space#CIELAB-CIEXYZ_conversions
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func xyztoLAB(x, y, z float64) (l, a, b float64) {
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refX, refY, refZ := 95.047, 100.000, 108.883 // Daylight, sRGB, Adobe-RGB, Observer D65, 2°
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varX := x / refX
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varY := y / refY
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varZ := z / refZ
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if varX > 0.008856 {
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varX = math.Pow(varX, (1.0 / 3.0))
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} else {
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varX = (7.787 * varX) + (16.0 / 116.0)
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}
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if varY > 0.008856 {
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varY = math.Pow(varY, (1.0 / 3.0))
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} else {
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varY = (7.787 * varY) + (16.0 / 116.0)
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}
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if varZ > 0.008856 {
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varZ = math.Pow(varZ, (1.0 / 3.0))
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} else {
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varZ = (7.787 * varZ) + (16.0 / 116.0)
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}
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l = (116 * varY) - 16
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a = 500 * (varX - varY)
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b = 200 * (varY - varZ)
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return l, a, b
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}
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// colorToLAB returns LAB representation of any color (without aplha)
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// https://en.wikipedia.org/wiki/Lab_color_space
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func colorToLAB(color color.Color) (l, a, b float64) {
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return xyztoLAB(colorToXYZ(color))
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}
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