public function getDataUri()
    {
        if (empty($this->image)) {
            $this->create();
        }

        ob_start();
        call_user_func('image'.$this->image_type, $this->image);
        $contents = ob_get_clean();

        return 'data:image/'.$this->image_type.';base64,'.base64_encode($contents);
    }