Added OKLCH color space

LCH.go

@@ -0,0 +1,56 @@
+package color
+
+import (
+	"math"
+)
+
+// LCH represents a color using lightness, chroma and hue (oklch).
+func LCH(lightness Value, chroma Value, hue Value) Color {
+	hue *= math.Pi / 180.0
+	a := chroma * math.Cos(hue)
+	b := chroma * math.Sin(hue)
+
+	r, g, b := labToRGB(lightness, a, b)
+
+	r = gammaCorrection(r)
+	g = gammaCorrection(g)
+	b = gammaCorrection(b)
+
+	return Color{r, g, b}
+}
+
+// LAB to linear sRGB
+// Source: https://bottosson.github.io/posts/oklab/
+func labToRGB(lightness Value, a Value, b Value) (Value, Value, Value) {
+	l := lightness + 0.3963377773761749*a + 0.21580375730991364*b
+	m := lightness - 0.10556134581565857*a - 0.0638541728258133*b
+	s := lightness - 0.08948418498039246*a - 1.2914855480194092*b
+
+	l = l * l * l
+	m = m * m * m
+	s = s * s * s
+
+	red := 4.0767416621*l - 3.3077115913*m + 0.2309699292*s
+	green := -1.2684380046*l + 2.6097574011*m - 0.3413193965*s
+	blue := -0.0041960863*l - 0.7034186147*m + 1.7076147010*s
+
+	return red, green, blue
+}
+
+// Gamma correction
+// Source: IEC 61966-2-2
+func gammaCorrection(x Value) Value {
+	if x < 0 {
+		return 0
+	}
+
+	if x <= 0.0031308 {
+		return 12.92 * x
+	}
+
+	if x < 1.0 {
+		return 1.055*math.Pow(x, 1/2.4) - 0.055
+	}
+
+	return 1.0
+}