var theURL=window.location.href;
var theSpot=theURL.indexOf(".jp2");
var newURL=theURL.substring(0,theSpot-4);
var theNumber=theURL.substring(parseInt(theSpot)-4,parseInt(theSpot));
theNumber=parseInt(theNumber)+1;
theNumberStr=("0000" + theNumber).slice(-4);
newURL=newURL+theNumberStr+theURL.substring(theSpot);
window.location.href=newURL;