function imageRefresh() {
  var pbsrcUrl = document.getElementById('productphoto').getAttribute('src');
  var urlSplit = pbsrcUrl.lastIndexOf('/') + 1;
  var urlStart = pbsrcUrl.substring(0,urlSplit);
  var urlEnd = pbsrcUrl.substring(urlSplit, 500);
  pbsrcUrl = urlStart + 'large-' +urlEnd;
  document.getElementById('productphoto').setAttribute('pbsrc',pbsrcUrl);
}