@fimbul-works/vec-color/dist/gamut.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 { labToRGB, rgbToLAB } from "./lab";
import { Vec3 } from "@fimbul-works/vec";
/**
 * Checks if a color is within the sRGB gamut
 * @param color Color to check
 * @returns Boolean indicating if color is in gamut
 */
export function isInGamut(color) {
    return (color.x >= 0 &&
        color.x <= 1 &&
        color.y >= 0 &&
        color.y <= 1 &&
        color.z >= 0 &&
        color.z <= 1);
}
/**
 * Clips a color to the sRGB gamut
 * Simple but can lose relationships between colors
 * @param color Color to clip
 * @returns Clipped color
 */
export function clipToGamut(color) {
    return new Vec3(Math.min(1, Math.max(0, color.x)), Math.min(1, Math.max(0, color.y)), Math.min(1, Math.max(0, color.z)));
}
/**
 * Compresses out-of-gamut colors while preserving relationships
 * More sophisticated than clipping but more computationally expensive
 * @param color Color to compress
 * @param preserveHue Whether to preserve the color's hue (default: true)
 * @returns Compressed color within gamut
 */
export function compressToGamut(color, preserveHue = true) {
    if (isInGamut(color))
        return color;
    const lab = rgbToLAB(color);
    let compressed;
    if (preserveHue) {
        // Preserve hue by adjusting only lightness and chroma
        const L = lab.x;
        const a = lab.y;
        const b = lab.z;
        const chroma = Math.sqrt(a * a + b * b);
        // Binary search for maximum in-gamut chroma
        let low = 0;
        let high = chroma;
        let bestInGamut = clipToGamut(color);
        for (let i = 0; i < 8; i++) {
            const mid = (low + high) / 2;
            const scale = mid / chroma;
            const testLab = new Vec3(L, a * scale, b * scale);
            const testRgb = labToRGB(testLab);
            if (isInGamut(testRgb)) {
                bestInGamut = testRgb;
                low = mid;
            }
            else {
                high = mid;
            }
        }
        compressed = bestInGamut;
    }
    else {
        // Simple compression in LAB space
        const center = new Vec3(50, 0, 0); // LAB middle gray
        const vector = lab.subtract(center);
        let scale = 1;
        while (!isInGamut((compressed = labToRGB(center.add(vector.scale(scale))))) &&
            scale > 0) {
            scale *= 0.9;
        }
    }
    return compressed;
}
/**
 * Projects an out-of-gamut color back into gamut while preserving lightness
 * Useful for maintaining perceived brightness while ensuring displayable colors
 * @param color Color to project
 * @returns Projected in-gamut color
 */
export function projectToGamut(color) {
    if (isInGamut(color))
        return color;
    const lab = rgbToLAB(color);
    const L = lab.x;
    let result = clipToGamut(color);
    let resultLab = rgbToLAB(result);
    // Adjust result to maintain original lightness
    const lightnessDiff = L - resultLab.x;
    if (Math.abs(lightnessDiff) > 0.01) {
        resultLab = new Vec3(L, resultLab.y, resultLab.z);
        result = clipToGamut(labToRGB(resultLab));
    }
    return result;
}