am.freeze();
			
			// swap button sets
			document.getElementById('pre_take_buttons').style.display = 'none';
			document.getElementById('post_take_buttons').style.display = '';
		}
		
		function cancel_preview() {
			// cancel preview freeze and return to live camera view
			Webcam.unfreeze();
			
			// swap buttons back to first set
			document.getElementById('pre_take_buttons').style.display = '';
			document.getElementById('post_take_buttons').style.display = 'none';
		}
		
		function save_photo() {
		