import { GainMapMetadata } from '../../../core/types';
/**
 * Extracts ISO 21496-1 gain map metadata from a JPEG file
 *
 * Looks for APP2 segments carrying the ISO 21496-1 namespace, skipping
 * the version-only segment stored in the primary image.
 *
 * `0xFF 0xE2` cannot appear inside entropy-coded data, so a byte scan is safe.
 *
 * @category Decoding Functions
 * @group Decoding Functions
 * @param input an `Uint8Array` containing an encoded JPEG file
 * @returns the parsed metadata or `undefined` if no supported ISO 21496-1 metadata is found
 */
export declare const extractISO: (input: Uint8Array) => GainMapMetadata | undefined;