public function save($file = NULL)
    {
        if(is_null($file) && $this->storage)
        {
            $this->storage->save($this);
        }
        elseif(!is_null($file))
        {
            $this->savePicture($file);
        }
        else
        {
            trigger_error('Image file to save is not defined', E_USER_WARNING);
        }
    }