var window_handle = null;
function open_image(href)
{
  if (!window.open)
    return true;

  if (typeof href == "undefined")
    return true;

  if (href == null)
    return true;

  if (href == "")
    return true;

  if (window_handle != null)
    if (!window_handle.closed)
      window_handle.close();

  window_handle = window.open(href,"photo","height=390,width=520,menubar=0,status=0,scrollbars,resizable,toolbar");
  return false;
}