function changePicture() {

	switch (document.getElementById("headerPicture").className) {

		case "picture1": document.getElementById("headerPicture").className="picture2"; break;
		case "picture2": document.getElementById("headerPicture").className="picture3"; break;
		case "picture3": document.getElementById("headerPicture").className="picture4"; break;
		case "picture4": document.getElementById("headerPicture").className="picture1"; break;
		default: document.getElementById("headerPicture").className="picture1"; break;

	}

	setTimeout("changePicture();",5000);

}