function alternarImg(nombre,ruta){
   var obj = new Object();
   obj = nombre;
   obj.src = ruta;
}
function activaCapa(capa){
   if(document.getElementById){
      var obj = document.getElementById(capa);
 	  obj.style.visibility="visible";
  }else if(document.layers){
 	 document.layers[capa].visibility="show";
  }else if (document.all){
 	 document.all[capa].style.visibility="visible"; 
  }
}

function desactivaCapa(capa){
   var obj = document.getElementById(capa);
   obj.style.visibility="hidden";
}