bouton1 = new Image();
bouton1.src = "img/btnaccov.jpg";

bouton2 = new Image();
bouton2.src = "img/btnartov.jpg";

bouton3 = new Image();
bouton3.src = "img/btnactov.jpg";

bouton4 = new Image();
bouton4.src = "img/btnconov.jpg";