$(document).ready(function() {
	$('.ro').hover(function() {
		//over
		var newImage = $(this).attr('src').replace(/^(.*?)(\.(?:gif|jpg|png))$/, "$1_o$2");
		$(this).attr('src', newImage);
	 },
	function() {
		//out
		var newImage = $(this).attr('src').replace('_o.', '.');
		$(this).attr('src', newImage);
	 })
});