/**
 * @public
 */
export interface RelativeLuminance {
    /**
     * A number between 0 and 1, calculated by {@link https://www.w3.org/WAI/GL/wiki/Relative_luminance}
     */
    readonly relativeLuminance: number;
}
/**
 * @internal
 */
export declare function contrast(a: RelativeLuminance, b: RelativeLuminance): number;