function popup(name, w, h)
{
  window.open("show_img.php?"+name, "foto","tollbar=no,menubar=no,location=no,personalbar=no,scrollbars=no,status=no,resizable=no,width="+w+",height="+h+", top="+((screen.height/2)-(h/2))+",left="+((screen.width/2)-(w/2)));
}