$(document).ready(function(){
 
	$(".roll").hover(
	function() {
		curr = $(this).find("img").attr("src");
		over = curr.replace(/_up\./, '_over.');
		$(this).find("img").attr({ src: over});
	},
	function() {
		$(this).find("img").attr({ src: curr});
	}
	)
	
	$(".roll").find("img").each(function(i) {
		temp = this.src;
		pre = temp.replace(/_up\./, '_over.');
		preload_image_object = new Image();
		preload_image_object.src = pre;
	})
 
});