One thing that comes to mind is JS-less image preview, clicking on an image thumbnail reveals the full preview.
Though that wouldn't have a method of closing the full image afterwards, if you have a few thumbnails and want one full to be open at a time (closing when the next is selected).
Though that wouldn't have a method of closing the full image afterwards, if you have a few thumbnails and want one full to be open at a time (closing when the next is selected).