/**
 * Determines the extension of a file based on its URI and MIME type.
 *
 * If the MIME type is not provided, it is inferred from the URI.
 *
 * Returns a default `png` extension if the extension is unknown.
 *
 * @param {string} uri - The URI of the image
 * @param {string} mimeType - The MIME type of the image
 */
export declare function getFileExtension(uri: string, mimeType?: string): string;
/**
 * Extracts the base name of a file from its URI.
 *
 * @param {string} filename - The name of the file
 */
export declare function getFileBasename(filename: string): string;