var newwindow = ''
function popitup(imgControl) {
    var img = imgControl.src;
    var imgSplit1 = img.split("/");
    var imgSplit2 = imgSplit1[imgSplit1.length - 1].split(".");
    var url = 'LargePic.htm?loc=Images/' + imgSplit2[0] + '_popup.' + imgSplit2[1];

    if (newwindow.location && !newwindow.closed) {
        newwindow.location.href = url;
        newwindow.focus();
    }
    else {
        newwindow = window.open(url, 'htmlname', 'status=0,toolbar=0,location=0,menubar=0,directories=0,resizable=0,scrollbars=0,height=600,width=600');
    }
}