code: function (fn) {
  
  		var writeBuffer = new streamBuffers.WritableStreamBuffer({
  			initialSize: (100 * 1024), incrementAmount: (10 * 1024)
  		});
  
  		fn = fn || function () {};
  
  		this._image.pack().pipe(writeBuffer).once('close', function () {
  			this._image.removeListener('error', fn);
  			fn(undefined, writeBuffer.getContents());
  		}.bind(this)).once('error', function (err) {
  			this._image.removeListener('close', fn);
  			fn(err);
  		}.bind(this));
  	}
docs: Writes the image to a buffer
  
  @method toBlob
  @param {function} fn Callback