function swap(){

	if((document.getElementById('image_centrale').style.visibility  == "visible") == 1 ){
	document.getElementById('image_centrale').style.visibility = "hidden";
	document.getElementById('petites_images').style.visibility = "visible";
	}else{
	document.getElementById('image_centrale').style.visibility = "visible";
	document.getElementById('petites_images').style.visibility = "hidden";
	}
}
//////////////////////////////////////////////////////
function versCentre(data){
var nom = data.substring(data.lastIndexOf('/')+4);
document.getElementById("image_centrale").src = nom;
swap();
}