Add color spaces for Luv, LCHuv, HSLuv and HPLuv.

get/modules.json

@@ -153,6 +153,33 @@
 			"id": "acescg",
 			"url": "https://en.wikipedia.org/wiki/Academy_Color_Encoding_System",
 			"description": "Scene-referred Academy Color Encoding System, using the wide gamut but physically realizable AP1 primaries and linear-light encoding. Used for physical rendering."
+		},
+		{
+			"name": "Luv",
+			"id": "luv",
+			"url": "https://en.wikipedia.org/wiki/CIELUV",
+			"description": ""
+		},
+		{
+			"name": "LCHuv",
+			"id": "lchuv",
+			"dependencies": ["luv"],
+			"url": "https://en.wikipedia.org/wiki/CIELUV",
+			"description": "The polar (Hue, Chroma) form of CIE Luv."
+		},
+		{
+			"name": "HSLuv",
+			"id": "hsluv",
+			"dependencies": ["lchuv"],
+			"url": "https://www.hsluv.org/comparison/",
+			"description": "The HSLuv color space is a perceptually uniform adaptation of the traditional HSL (Hue, Saturation, Lightness) color model. Engineered upon the foundations of the CIELUV color space, HSLuv ensures that colors that appear equally spaced in its representation also present consistent perceptual differences to the human observer. This results in a color space where changes in hue, saturation, or lightness produce predictable and coherent visual outcomes, addressing inconsistencies and unpredictable color shifts often found in standard HSL."
+		},
+		{
+			"name": "HPLuv",
+			"id": "hpluv",
+			"dependencies": ["lchuv"],
+			"url": "https://www.hsluv.org/comparison/",
+			"description": "The HPLuv color space emphasizes perceptual uniformity specifically in its lightness component. HPLuv ensures that changes in lightness are consistently perceived by the human eye, regardless of the hue or saturation of the color. The resulting palette is a subset of sRGB and the colors are mainly pastel."
 		}
 	],
 	"optional": [

src/parse.js

@@ -4,6 +4,56 @@ import ColorSpace from "./space.js";
 
 const noneTypes = new Set(["<number>", "<percentage>", "<angle>"]);
 
+/**
+ * Validates the coordinates of a color against a format's coord grammar and
+ * maps the coordinates to the range or refRange of the coordinates.
+ * @param {ColorSpace} space - Colorspace the coords are in
+ * @param {object} format - the format object to validate against
+ * @param {string} name - the name of the color function. e.g. "oklab" or "color"
+ * @returns {object[]} - an array of type metadata for each coordinate
+ */
+function coerceCoords (space, format, name, coords) {
+	let types = Object.entries(space.coords).map(([id, coordMeta], i) => {
+		let coordGrammar = format.coordGrammar[i];
+		let arg = coords[i];
+		let providedType = arg?.type;
+
+		// Find grammar alternative that matches the provided type
+		// Non-strict equals is intentional because we are comparing w/ string objects
+		let type;
+		if (arg.none) {
+			type = coordGrammar.find(c => noneTypes.has(c));
+		}
+		else {
+			type = coordGrammar.find(c => c == providedType);
+		}
+
+		// Check that each coord conforms to its grammar
+		if (!type) {
+			// Type does not exist in the grammar, throw
+			let coordName = coordMeta.name || id;
+			throw new TypeError(`${providedType ?? arg.raw} not allowed for ${coordName} in ${name}()`);
+		}
+
+		let fromRange = type.range;
+
+		if (providedType === "<percentage>") {
+			fromRange ||= [0, 1];
+		}
+
+		let toRange = coordMeta.range || coordMeta.refRange;
+
+		if (fromRange && toRange) {
+			coords[i] = util.mapRange(fromRange, toRange, coords[i]);
+		}
+
+		return type;
+	});
+
+	return types;
+}
+
+
 /**
  * Convert a CSS Color string to a color object
  * @param {string} str
@@ -24,7 +74,6 @@ export default function parse (str, {meta} = {}) {
 	if (env.parsed) {
 		// Is a functional syntax
 		let name = env.parsed.name;
-
 		if (name === "color") {
 			// color() function
 			let id = env.parsed.args.shift();
@@ -40,8 +89,14 @@ export default function parse (str, {meta} = {}) {
 						// If less <number>s or <percentage>s are provided than parameters that the colorspace takes, the missing parameters default to 0. (This is particularly convenient for multichannel printers where the additional inks are spot colors or varnishes that most colors on the page won’t use.)
 						const coords = Object.keys(space.coords).map((_, i) => env.parsed.args[i] || 0);
 
+						let types;
+
+						if (colorSpec.coordGrammar) {
+							types = coerceCoords(space, colorSpec, "color", coords);
+						}
+
 						if (meta) {
-							meta.formatId = "color";
+							Object.assign(meta, {formatId: "color", types});
 						}
 
 						return {spaceId: space.id, coords, alpha};
@@ -74,46 +129,10 @@ export default function parse (str, {meta} = {}) {
 					}
 
 					let coords = env.parsed.args;
-
 					let types;
 
 					if (format.coordGrammar) {
-						types = Object.entries(space.coords).map(([id, coordMeta], i) => {
-							let coordGrammar = format.coordGrammar[i];
-							let arg = coords[i];
-							let providedType = arg?.type;
-
-							// Find grammar alternative that matches the provided type
-							// Non-strict equals is intentional because we are comparing w/ string objects
-							let type;
-							if (arg.none) {
-								type = coordGrammar.find(c => noneTypes.has(c));
-							}
-							else {
-								type = coordGrammar.find(c => c == providedType);
-							}
-
-							// Check that each coord conforms to its grammar
-							if (!type) {
-								// Type does not exist in the grammar, throw
-								let coordName = coordMeta.name || id;
-								throw new TypeError(`${providedType ?? arg.raw} not allowed for ${coordName} in ${name}()`);
-							}
-
-							let fromRange = type.range;
-
-							if (providedType === "<percentage>") {
-								fromRange ||= [0, 1];
-							}
-
-							let toRange = coordMeta.range || coordMeta.refRange;
-
-							if (fromRange && toRange) {
-								coords[i] = util.mapRange(fromRange, toRange, coords[i]);
-							}
-
-							return type;
-						});
+						types = coerceCoords(space, format, name, coords);
 					}
 
 					if (meta) {
@@ -160,4 +179,4 @@ export default function parse (str, {meta} = {}) {
 
 	// If we're here, we couldn't parse
 	throw new TypeError(`Could not parse ${str} as a color. Missing a plugin?`);
-}
+}

src/space.js

@@ -19,6 +19,15 @@ export default class ColorSpace {
 			this.toBase = options.toBase;
 		}
 
+		if (options.gamutCheck)	{
+			if (options.gamutCheck === "self") {
+				this.gamutCheck = this;
+			}
+			else {
+				this.gamutCheck = ColorSpace.get(options.gamutCheck);
+			}
+		}
+
 		// Coordinate metadata
 
 		let coords = options.coords ?? this.base.coords;
@@ -68,8 +77,17 @@ export default class ColorSpace {
 	}
 
 	inGamut (coords, {epsilon = ε} = {}) {
-		if (this.isPolar) {
+		// If the gamutCheck space is specified and not ourself then
+		// use the gamutCheck space to check if the coords are in gamut
+		if (this.gamutCheck && !this.equals(this.gamutCheck)) {
+			coords = this.to(this.gamutCheck, coords);
+			return this.gamutCheck.inGamut(coords, {epsilon});
+		}
+
+		if (this.isPolar && !this.equals(this.gamutCheck)) {
 			// Do not check gamut through polar coordinates
+			// unless this space is the gamutCheck space
+
 			coords = this.toBase(coords);
 
 			return this.base.inGamut(coords, {epsilon});

src/spaces/hpluv.js

@@ -0,0 +1,129 @@
+/*
+Adapted from: https://github.com/hsluv/hsluv-javascript/blob/14b49e6cf9a9137916096b8487a5372626b57ba4/src/hsluv.ts
+
+Copyright (c) 2012-2022 Alexei Boronine
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+*/
+
+import ColorSpace from "../space.js";
+import LCHuv from "./lchuv.js";
+import {fromXYZ_M} from "./srgb-linear.js";
+import {calculateBoundingLines} from "./hsluv.js";
+
+const ε = 216/24389;  // 6^3/29^3 == (24/116)^3
+const κ = 24389/27;   // 29^3/3^3
+
+const m_r0 = fromXYZ_M[0][0];
+const m_r1 = fromXYZ_M[0][1];
+const m_r2 = fromXYZ_M[0][2];
+const m_g0 = fromXYZ_M[1][0];
+const m_g1 = fromXYZ_M[1][1];
+const m_g2 = fromXYZ_M[1][2];
+const m_b0 = fromXYZ_M[2][0];
+const m_b1 = fromXYZ_M[2][1];
+const m_b2 = fromXYZ_M[2][2];
+
+function distanceFromOrigin (slope, intercept) {
+	return Math.abs(intercept) / Math.sqrt(Math.pow(slope, 2) + 1);
+}
+
+function calcMaxChromaHpluv (lines) {
+	let r0 = distanceFromOrigin(lines.r0s, lines.r0i);
+	let r1 = distanceFromOrigin(lines.r1s, lines.r1i);
+	let g0 = distanceFromOrigin(lines.g0s, lines.g0i);
+	let g1 = distanceFromOrigin(lines.g1s, lines.g1i);
+	let b0 = distanceFromOrigin(lines.b0s, lines.b0i);
+	let b1 = distanceFromOrigin(lines.b1s, lines.b1i);
+
+	return Math.min(r0, r1, g0, g1, b0, b1);
+}
+
+export default new ColorSpace({
+	id: "hpluv",
+	name: "HPLuv",
+	coords: {
+		h: {
+			refRange: [0, 360],
+			type: "angle",
+			name: "Hue"
+		},
+		s: {
+			range: [0, 100],
+			name: "Saturation"
+		},
+		l: {
+			range: [0, 100],
+			name: "Lightness"
+		}
+	},
+
+	base: LCHuv,
+	gamutCheck: "self",
+
+	// Convert LCHuv to HPLuv
+	fromBase (lch) {
+		let [L, c, h] = lch;
+		let s, l;
+
+        if (L > 99.9999999) {
+            s = 0;
+            l = 100;
+        }
+		else if (L < 0.00000001) {
+            s = 0;
+            l = 0;
+        }
+		else {
+            let lines = calculateBoundingLines(L);
+            let max = calcMaxChromaHpluv(lines);
+            s = c / max * 100;
+            l = L;
+        }
+		return [h, s, l];
+	},
+
+	// Convert HPLuv to LCHuv
+	toBase (hsl) {
+		let [h, s, l] = hsl;
+		let L, c;
+        if (l > 99.9999999) {
+            L = 100;
+            c = 0;
+        }
+		else if (l < 0.00000001) {
+            L = 0;
+            c = 0;
+        }
+		else {
+            L = l;
+			let lines = calculateBoundingLines(L);
+			let max = calcMaxChromaHpluv(lines, h);
+			c = max / 100 * s;
+        }
+		return [L, c, h];
+	},
+
+	formats: {
+		color: {
+			id: "--hpluv",
+			coords: ["<number> | <angle>", "<percentage> | <number>", "<percentage> | <number>"]
+		}
+	},
+});