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| import { ColorHSL } from "./colorHSL";
import { ColorHSV } from "./colorHSV";
import { ColorLAB } from "./colorLAB";
import { ColorLCH } from "./colorLCH";
import { ColorRGBA64 } from "./colorRGBA64";
import { ColorXYZ } from "./colorXYZ";
import { degreesToRadians, radiansToDegrees } from "./mathUtils";
// All hue values are in degrees rather than radians or normalized
// All conversions use the D65 2 degree white point for XYZ
// Info on conversions and constants used can be found in the following:
// https://en.wikipedia.org/wiki/CIELAB_color_space
// https://en.wikipedia.org/wiki/Illuminant_D65
// https://ninedegreesbelow.com/photography/xyz-rgb.html
// http://user.engineering.uiowa.edu/~aip/Misc/ColorFAQ.html
// https://web.stanford.edu/~sujason/ColorBalancing/adaptation.html
// http://brucelindbloom.com/index.html
// The alpha channel of the input is ignored
export function rgbToLuminance(rgb: ColorRGBA64): number {
function luminanceHelper(i: number): number {
if (i <= 0.03928) {
return i / 12.92;
}
return Math.pow((i + 0.055) / 1.055, 2.4);
}
const r: number = luminanceHelper(rgb.r);
const g: number = luminanceHelper(rgb.g);
const b: number = luminanceHelper(rgb.b);
return r * 0.2126 + g * 0.7152 + b * 0.0722;
}
// The alpha channel of the input is ignored
export function contrastRatio(a: ColorRGBA64, b: ColorRGBA64): number {
const luminanceA: number = rgbToLuminance(a);
const luminanceB: number = rgbToLuminance(b);
if (luminanceA > luminanceB) {
return (luminanceA + 0.05) / (luminanceB + 0.05);
}
return (luminanceB + 0.05) / (luminanceA + 0.05);
}
// The alpha channel of the input is ignored
export function rgbToHSL(rgb: ColorRGBA64): ColorHSL {
const max: number = Math.max(rgb.r, rgb.g, rgb.b);
const min: number = Math.min(rgb.r, rgb.g, rgb.b);
const delta: number = max - min;
let hue: number = 0;
if (delta !== 0) {
if (max === rgb.r) {
hue = 60 * (((rgb.g - rgb.b) / delta) % 6);
} else if (max === rgb.g) {
hue = 60 * ((rgb.b - rgb.r) / delta + 2);
} else {
hue = 60 * ((rgb.r - rgb.g) / delta + 4);
}
}
if (hue < 0) {
hue += 360;
}
const lum: number = (max + min) / 2;
let sat: number = 0;
if (delta !== 0) {
sat = delta / (1 - Math.abs(2 * lum - 1));
}
return new ColorHSL(hue, sat, lum);
}
export function hslToRGB(hsl: ColorHSL, alpha: number = 1): ColorRGBA64 {
const c: number = (1 - Math.abs(2 * hsl.l - 1)) * hsl.s;
const x: number = c * (1 - Math.abs(((hsl.h / 60) % 2) - 1));
const m: number = hsl.l - c / 2;
let r: number = 0;
let g: number = 0;
let b: number = 0;
if (hsl.h < 60) {
r = c;
g = x;
b = 0;
} else if (hsl.h < 120) {
r = x;
g = c;
b = 0;
} else if (hsl.h < 180) {
r = 0;
g = c;
b = x;
} else if (hsl.h < 240) {
r = 0;
g = x;
b = c;
} else if (hsl.h < 300) {
r = x;
g = 0;
b = c;
} else Eif (hsl.h < 360) {
r = c;
g = 0;
b = x;
}
return new ColorRGBA64(r + m, g + m, b + m, alpha);
}
// The alpha channel of the input is ignored
export function rgbToHSV(rgb: ColorRGBA64): ColorHSV {
const max: number = Math.max(rgb.r, rgb.g, rgb.b);
const min: number = Math.min(rgb.r, rgb.g, rgb.b);
const delta: number = max - min;
let hue: number = 0;
if (delta !== 0) {
if (max === rgb.r) {
hue = 60 * (((rgb.g - rgb.b) / delta) % 6);
} else if (max === rgb.g) {
hue = 60 * ((rgb.b - rgb.r) / delta + 2);
} else {
hue = 60 * ((rgb.r - rgb.g) / delta + 4);
}
}
if (hue < 0) {
hue += 360;
}
let sat: number = 0;
if (max !== 0) {
sat = delta / max;
}
return new ColorHSV(hue, sat, max);
}
export function hsvToRGB(hsv: ColorHSV, alpha: number = 1): ColorRGBA64 {
const c: number = hsv.s * hsv.v;
const x: number = c * (1 - Math.abs(((hsv.h / 60) % 2) - 1));
const m: number = hsv.v - c;
let r: number = 0;
let g: number = 0;
let b: number = 0;
if (hsv.h < 60) {
r = c;
g = x;
b = 0;
} else if (hsv.h < 120) {
r = x;
g = c;
b = 0;
} else if (hsv.h < 180) {
r = 0;
g = c;
b = x;
} else if (hsv.h < 240) {
r = 0;
g = x;
b = c;
} else if (hsv.h < 300) {
r = x;
g = 0;
b = c;
} else Eif (hsv.h < 360) {
r = c;
g = 0;
b = x;
}
return new ColorRGBA64(r + m, g + m, b + m, alpha);
}
export function lchToLAB(lch: ColorLCH): ColorLAB {
let a: number = 0;
let b: number = 0;
if (lch.h !== 0) {
a = Math.cos(degreesToRadians(lch.h)) * lch.c;
b = Math.sin(degreesToRadians(lch.h)) * lch.c;
}
return new ColorLAB(lch.l, a, b);
}
// The discontinuity in the C parameter at 0 means that floating point errors will often result in values near 0 giving unpredictable results.
// EG: 0.0000001 gives a very different result than -0.0000001
// More info about the atan2 function: https://en.wikipedia.org/wiki/Atan2
export function labToLCH(lab: ColorLAB): ColorLCH {
let h: number = 0;
if (lab.b !== 0 || lab.a !== 0) {
h = radiansToDegrees(Math.atan2(lab.b, lab.a));
}
if (h < 0) {
h += 360;
}
const c: number = Math.sqrt(lab.a * lab.a + lab.b * lab.b);
return new ColorLCH(lab.l, c, h);
}
export function labToXYZ(lab: ColorLAB): ColorXYZ {
const fy: number = (lab.l + 16) / 116;
const fx: number = fy + lab.a / 500;
const fz: number = fy - lab.b / 200;
const xcubed: number = Math.pow(fx, 3);
const ycubed: number = Math.pow(fy, 3);
const zcubed: number = Math.pow(fz, 3);
let x: number = 0;
if (xcubed > ColorLAB.epsilon) {
x = xcubed;
} else {
x = (116 * fx - 16) / ColorLAB.kappa;
}
let y: number = 0;
if (lab.l > ColorLAB.epsilon * ColorLAB.kappa) {
y = ycubed;
} else {
y = lab.l / ColorLAB.kappa;
}
let z: number = 0;
if (zcubed > ColorLAB.epsilon) {
z = zcubed;
} else {
z = (116 * fz - 16) / ColorLAB.kappa;
}
x = ColorXYZ.whitePoint.x * x;
y = ColorXYZ.whitePoint.y * y;
z = ColorXYZ.whitePoint.z * z;
return new ColorXYZ(x, y, z);
}
export function xyzToLAB(xyz: ColorXYZ): ColorLAB {
function xyzToLABHelper(i: number): number {
if (i > ColorLAB.epsilon) {
return Math.pow(i, 1 / 3);
}
return (ColorLAB.kappa * i + 16) / 116;
}
const x: number = xyzToLABHelper(xyz.x / ColorXYZ.whitePoint.x);
const y: number = xyzToLABHelper(xyz.y / ColorXYZ.whitePoint.y);
const z: number = xyzToLABHelper(xyz.z / ColorXYZ.whitePoint.z);
const l: number = 116 * y - 16;
const a: number = 500 * (x - y);
const b: number = 200 * (y - z);
return new ColorLAB(l, a, b);
}
// The alpha channel of the input is ignored
export function rgbToXYZ(rgb: ColorRGBA64): ColorXYZ {
function rgbToXYZHelper(i: number): number {
if (i <= 0.04045) {
return i / 12.92;
}
return Math.pow((i + 0.055) / 1.055, 2.4);
}
const r: number = rgbToXYZHelper(rgb.r);
const g: number = rgbToXYZHelper(rgb.g);
const b: number = rgbToXYZHelper(rgb.b);
const x: number = r * 0.4124564 + g * 0.3575761 + b * 0.1804375;
const y: number = r * 0.2126729 + g * 0.7151522 + b * 0.072175;
const z: number = r * 0.0193339 + g * 0.119192 + b * 0.9503041;
return new ColorXYZ(x, y, z);
}
// Note that the xyz color space is signifigantly larger than sRGB. As such, this can return colors rgb values greater than 1 or less than 0
export function xyzToRGB(xyz: ColorXYZ, alpha: number = 1): ColorRGBA64 {
function xyzToRGBHelper(i: number): number {
if (i <= 0.0031308) {
return i * 12.92;
}
return 1.055 * Math.pow(i, 1 / 2.4) - 0.055;
}
const r: number = xyzToRGBHelper(
xyz.x * 3.2404542 - xyz.y * 1.5371385 - xyz.z * 0.4985314
);
const g: number = xyzToRGBHelper(
xyz.x * -0.969266 + xyz.y * 1.8760108 + xyz.z * 0.041556
);
const b: number = xyzToRGBHelper(
xyz.x * 0.0556434 - xyz.y * 0.2040259 + xyz.z * 1.0572252
);
return new ColorRGBA64(r, g, b, alpha);
}
// The alpha channel of the input is ignored
export function rgbToLAB(rgb: ColorRGBA64): ColorLAB {
return xyzToLAB(rgbToXYZ(rgb));
}
// Note that the xyz color space (which the conversion from LAB uses) is signifigantly larger than sRGB. As such, this can return colors rgb values greater than 1 or less than 0
export function labToRGB(lab: ColorLAB, alpha: number = 1): ColorRGBA64 {
return xyzToRGB(labToXYZ(lab), alpha);
}
// The alpha channel of the input is ignored
export function rgbToLCH(rgb: ColorRGBA64): ColorLCH {
return labToLCH(rgbToLAB(rgb));
}
export function lchToRGB(lch: ColorLCH, alpha: number = 1): ColorRGBA64 {
return labToRGB(lchToLAB(lch), alpha);
}
export function temperatureToRGB(tempKelvin: number, alpha: number = 1): ColorRGBA64 {
// The constants I could find assumed a decimal range of [0,255] for each channel. Just going to put a /255.0 at the end
let r: number = 0;
let g: number = 0;
let b: number = 0;
if (tempKelvin <= 1000) {
tempKelvin = 1000;
} else if (tempKelvin >= 40000) {
tempKelvin = 40000;
}
if (tempKelvin < 6600.0) {
r = 255.0;
g = tempKelvin / 100.0 - 2.0;
g =
-155.25485562709179 -
0.44596950469579133 * g +
104.49216199393888 * Math.log(g);
} else {
r = tempKelvin / 100.0 - 55.0;
r = 351.97690566805693 + 0.114206453784165 * r - 40.25366309332127 * Math.log(r);
g = tempKelvin / 100.0 - 50.0;
g = 325.4494125711974 + 0.07943456536662342 * g - 28.0852963507957 * Math.log(g);
}
if (tempKelvin >= 6600.0) {
b = 255.0;
} else if (tempKelvin < 2000.0) {
b = 0.0;
} else {
b = tempKelvin / 100.0 - 10;
b =
-254.76935184120902 +
0.8274096064007395 * b +
115.67994401066147 * Math.log(b);
}
return new ColorRGBA64(r / 255, g / 255, b / 255, alpha);
}
// The alpha channel of the input is ignored
export function rgbToTemperature(rgb: ColorRGBA64): number {
let t: number = 0;
let min: number = 1000;
let max: number = 40000;
while (max - min > 0.4) {
t = (max + min) / 2.0;
const testColor: ColorRGBA64 = temperatureToRGB(t);
if (testColor.b / testColor.r >= rgb.b / rgb.r) {
max = t;
} else {
min = t;
}
}
return Math.round(t);
}
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