export declare function isGifAnimated(buffer: Buffer): boolean;
export declare function isWebPAnimated(buffer: Buffer): boolean;
export declare function isImageAnimated(buffer: Buffer, contentType: string): boolean;
/**
 * Inspects the first few bytes of a buffer to determine if
 * it matches the "magic number" of known file signatures.
 * https://en.wikipedia.org/wiki/List_of_file_signatures
 * also see https://github.com/vercel/next.js/blob/fabab8cf05da106410d97d818adf2f6b4742d614/packages/next/src/server/image-optimizer.ts
 * Why rewrite this when it's already done, Am I right?
 */
export declare function detectContentType(buffer: Buffer): "image/gif" | "image/webp" | "image/jpeg" | "image/png" | "image/svg+xml" | "image/avif" | "image/ico" | null;