@fimbul-works/vec-color/dist/lab.js

A comprehensive, type-safe color manipulation library for TypeScript that provides a wide range of color space conversions, blending operations, and accessibility utilities.

import { rgbToXYZ, xyzToRGB } from "./xyz";
import { Vec3 } from "@fimbul-works/vec";
// D65 reference white point
const WHITE_POINT_X = 0.95047;
const WHITE_POINT_Y = 1.0;
const WHITE_POINT_Z = 1.08883;
/**
 * Converts XYZ color to CIE LAB color space using D65 illuminant
 * LAB represents all visible colors with L for lightness (0-100), a for green-red, and b for blue-yellow
 * @param xyz - Vec3 containing XYZ values (each channel normalized)
 * @returns Vec3 containing LAB values (l: 0-100, a: -128-127, b: -128-127)
 */
export function xyzToLAB(xyz) {
    const [x, y, z] = xyz;
    const f = (t) => t > (6 / 29) ** 3 ? t ** (1 / 3) : (1 / 3) * (29 / 6) ** 2 * t + 4 / 29;
    return new Vec3(116 * f(y / WHITE_POINT_Y) - 16, 500 * (f(x / WHITE_POINT_X) - f(y / WHITE_POINT_Y)), 200 * (f(y / WHITE_POINT_Y) - f(z / WHITE_POINT_Z)));
}
/**
 * Converts CIE LAB color to XYZ color space using D65 illuminant
 * Transforms perceptually uniform LAB coordinates back to device-independent XYZ
 * @param lab - Vec3 containing LAB values (l: 0-100, a: -128-127, b: -128-127)
 * @returns Vec3 containing XYZ values (each channel normalized)
 */
export function labToXYZ(lab) {
    const [l, a, b] = lab;
    const finv = (t) => t > 6 / 29 ? t ** 3 : 3 * (6 / 29) ** 2 * (t - 4 / 29);
    const fy = (l + 16) / 116;
    const fx = fy + a / 500;
    const fz = fy - b / 200;
    return new Vec3(WHITE_POINT_X * finv(fx), WHITE_POINT_Y * finv(fy), WHITE_POINT_Z * finv(fz));
}
/**
 * Converts RGB color to CIE LAB color space
 * Provides a perceptually uniform color space useful for color difference calculations
 * @param rgb - Vec3 containing RGB values (each channel from 0 to 1)
 * @returns Vec3 containing LAB values (l: 0-100, a: -128-127, b: -128-127)
 */
export function rgbToLAB(rgb) {
    return xyzToLAB(rgbToXYZ(rgb));
}
/**
 * Converts CIE LAB color to RGB color space
 * Transforms perceptually uniform color coordinates to display-ready RGB values
 * @param lab - Vec3 containing LAB values (l: 0-100, a: -128-127, b: -128-127)
 * @returns Vec3 containing RGB values (each channel from 0 to 1)
 */
export function labToRGB(lab) {
    return xyzToRGB(labToXYZ(lab));
}