import { Color } from "three";
//#region src/color/distance.d.ts
/**
 * Perceptual distance between two colors in OKLAB space.
 * Euclidean distance in a perceptually uniform space.
 * Range: 0 (identical) to ~1.4 (maximum).
 */
declare function deltaEOklab(a: Color, b: Color): number;
/**
 * WCAG 2.1 relative luminance from a Three.js Color.
 * Rec. 709 coefficients applied directly — components are already working-space linear (the three.js default).
 */
declare function relativeLuminance(color: Color): number;
/**
 * WCAG 2.1 contrast ratio between two colors.
 * Returns 1 (identical) to 21 (max, black/white).
 */
declare function contrastRatio(a: Color, b: Color): number;
/**
 * Check WCAG 2.1 conformance level for a foreground/background pair.
 *
 * - AAA: contrast >= 7:1 (enhanced, normal text)
 * - AA: contrast >= 4.5:1 (minimum, normal text)
 * - AA-large: contrast >= 3:1 (minimum, large text / UI components)
 * - fail: contrast < 3:1
 */
declare function wcagLevel(foreground: Color, background: Color): 'AAA' | 'AA' | 'AA-large' | 'fail';
//#endregion
export { contrastRatio, deltaEOklab, relativeLuminance, wcagLevel };
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