jQuery(document).ready(function(){

			function switchImages(){
				var randomnumber=Math.floor(Math.random()*21)+1;
				$("#image_background").fadeTo(1500, 0.01, function(){
					$("#image_background").css("background-image","url(/images/jpegs/image"+randomnumber+".jpg)");
					});
				$("#image_background").fadeTo(1500,1);
			}

			switchImages();
			var img_interval = setInterval(switchImages,20000);

		});