Method isImage

/**
 * Checks if the file is an image
 *
 * @param   string  $fileName  The filename
 *
 * @return  boolean
 *
 * @since   3.2
 */
public static function isImage($fileName)
{
    static $imageTypes = 'xcf|odg|gif|jpg|jpeg|png|bmp|webp';
    return preg_match("/\\.(?:{$imageTypes})\$/i", $fileName);
}