var refresh = setInterval(function(){
	
	// create a new timestamp
	var timestamp = new Date();
	
	// keep track of the image we're going to work on
	var img = document.getElementById('id_of_your_img');
	
	// make sure the pic. exists before operation
	if(img){
	
		// get the source of the pic. (minus any previous appenditures)
		var src = img.getAttribute('src').replace(/\?time=.+$/i,"");
		
		// set the source of the pic. to the current src + timestamp (querystring)
		img.setAttribute('src',src +"?time="+timestamp.getSeconds());
	}
	
},1000);