function afficher_img(next)
    {
        img = "entete";
        fadeOut(img,100);
    
        document.getElementById(img).src = next;
        //document.getElementById(img).style.display = 'block';
        
        // affichage fondu
        fadeIn(img,0);
    }
    
    function setOpacity(obj, opacity)
    {
      opacity = (opacity == 100)?99.999:opacity;
      // IE/Win
      obj.style.filter = "alpha(opacity:"+opacity+")";
      // Safari<1.2, Konqueror
      obj.style.KHTMLOpacity = opacity/100;
      // Older Mozilla and Firefox
      obj.style.MozOpacity = opacity/100;
      // Safari 1.2, newer Firefox and Mozilla, CSS3
      obj.style.opacity = opacity/100;
    }
    
    function fadeIn(objId,opacity)
    {
      var duree = 50; /* variable duree affichage */
      if (document.getElementById) {
        obj = document.getElementById(objId);
        if (opacity <= 100) {
          setOpacity(obj, opacity);
          opacity += 10;
          window.setTimeout("fadeIn('"+objId+"',"+opacity+")", duree);
        }
      }
    }
    
    function fadeOut(objId,opacity)
    {
      var duree = 50; /* variable duree affichage */
      if (document.getElementById)
      {
        obj = document.getElementById(objId);
        if (opacity >= 0)
        {
          setOpacity(obj, opacity);
          opacity -= 10;
          window.setTimeout("fadeOut('"+objId+"',"+opacity+")", duree);
        }
      }
    }
    
    function verif_contact()
    {
      if ((document.getElementById("nom").value == "") || (document.getElementById("prenom").value == "") || (document.getElementById("email").value == "") || (document.getElementById("tel").value == "") || (document.getElementById("commentaires").value == ""))
    	{
        alert('Veuillez remplir tout les champs! Merci.');
      }
    	else
      {
        adresse = document.getElementById("email").value;
    	  var place = adresse.indexOf("@",1);
    	  var point = adresse.indexOf(".",place+1);
    	  if ((place > -1)&&(adresse.length >2)&&(point > 1))
    		{
    		  return(true);
    		}
    	  else
    		{
    		  alert('Entrez une adresse e-mail valide! Merci.');
    		  return(false);
    		}
    	}
    }        

  function aff_noir(gd_img)
  {
    document.getElementById("fd_noir").style.display="block";
    document.getElementById("img_fd_noir").src=gd_img;
  }