In the following image you will see two normal item frames with maps and two item frames with maps, but it’s empty:
To make an Map Item Frame, press [RClick], [LT] or [ZL] to reveal it, then, put it on the item frame.
To make a Large Item Frame (empty), you will need to be really quick. You will have to reveal the map and in the last 0,5 seconds before the map is trully revealed, place it at the item frame.