<html>
<head><title></title>
</head>
<body >
<div id = "div_background" style="background-image:url(b_4502E7D7BB561F83.jpg)">
test
</div>
<script language="javascript" type="text/javascript">
alert( document.getElementById("div_background").style.backgroundImage.replace("url(","").replace(")",""));
</script>
</body>
</html>