function swapImage(id,bit)
    {
        var imgsrc;
        if(bit==1){            
            imgsrc='images/'+id+'_over.gif';
            document.images[id].src=imgsrc;
         }
         else{
            imgsrc='images/'+id+'.gif';
            document.images[id].src=imgsrc;
         }
    }