function aTraiter(obj, prefixe)
{
 return obj.id != null &&
		obj.id.indexOf(prefixe) == 0;
}

function traiterCollection(collection, filtre, traiterElem)
{
 var n = collection.length;
 for(var i = 0; i < n ; i++)
  if(filtre == "" || aTraiter(collection[i], filtre))
	traiterElem(collection[i]);
}
		
function ChangerSource()
 {
	var temp = this.src;
	this.src = this.remp.src;
	this.remp.src = temp;
 }
 
 function Charger(img)
 {
  img.remp = new Image();
  img.remp.src = img.title;
  img.title = img.alt;
  img.onmouseover = img.onmouseout = ChangerSource;
 } 
 
 function précharger()
 {
   traiterCollection(document.images, "is_", Charger);
 } 
 
 function inverserDisplay(idimg)
 {
  if(document.images[idimg].style.display  == "none")
	document.images[idimg].style.display = "inline";
  else
	document.images[idimg].style.display = "none";  
 }