function MM_preloadImages() { //v3.0
  var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
    var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
    if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}}
}
<!--rotazione immagini-->
number_of_pictures="6";
var sctr="0";
var halt="0";
var isn=new Array();
for (i="0";i<number_of_pictures;i++){
 isn[i]=new Image();
}
isn[0].src="img/img1.jpg";
isn[1].src="img/img2.jpg";
isn[2].src="img/img3.jpg";
isn[3].src="img/img4.jpg";
isn[4].src="img/img5.jpg";
isn[5].src="img/img6.jpg";
function rotateIt(){
 if (halt!=1){
  sctr++;
  if (sctr>number_of_pictures-1){
   sctr=0;
   }
  document.picture.src=isn[sctr].src;
  setTimeout("rotateIt()","9000");
  }
 }
function dispIt(){
 parent.window.status=durl[sctr];
 }