(Информация о версии неизвестна, возможно, только в SVN)
Imagick::__toString — Returns the image as a string.
Returns the current image as string. This will only return a single image; it should not be used for Imagick objects that contain multiple images e.g. an animated GIF or PDF with multiple pages.
У этой функции нет параметров.
Returns the string content on success or an empty string on failure.