var current_photo = '1';
var interval;
function swapphoto(new_photo, auto)
 {    
  if(!auto)
   {
         clearInterval(interval);
   }
    document.getElementById("photo_" + current_photo).style.display="none";
    document.getElementById("photo_" + current_photo + "_on").style.display="none";
    document.getElementById("photo_" + current_photo + "_off").style.display="";
    current_photo = new_photo;
    document.getElementById("photo_" + new_photo).style.display="";
    document.getElementById("photo_" + new_photo + "_on").style.display="";
    document.getElementById("photo_" + new_photo + "_off").style.display="none"; 
}

   function autoSwap()
  {
        var count = parseInt(current_photo) + 1;
       if(count == 5) 
       {
            count = 1;
       }
       swapphoto(count.toString());
       interval = setInterval('autoSwap()');
   }