function switch_img (element) {
  if (element.className=="")
    {
      element.className="active";
      element.src=str_replace("_0","_active_0",element.src);
    }
  else
    {
      element.className="";
      element.src=str_replace("_active_0","_0",element.src);
    }
}
function str_replace(search, replace, subject) {
return subject.split(search).join(replace);
}