Normal1 = new Image();
Normal1.src = "../img/navigation/sitzen-button.png";     /* erste Standard-Grafik */
Highlight1 = new Image();
Highlight1.src = "../img/navigation/sitzen-button-on.png"; /* erste Highlight-Grafik */

Normal2 = new Image();
Normal2.src = "../img/navigation/essen-button.png";     /* zweite Standard-Grafik */
Highlight2 = new Image();
Highlight2.src = "../img/navigation/essen-button-on.png"; /* zweite Highlight-Grafik */

Normal3 = new Image();
Normal3.src = "../img/navigation/trinken-button.png";     /* dritte Standard-Grafik */
Highlight3 = new Image();
Highlight3.src = "../img/navigation/trinken-button-on.png"; /* dritte Highlight-Grafik */

Normal4 = new Image();
Normal4.src = "../img/navigation/schlafen-button.png";     /* dritte Standard-Grafik */
Highlight4 = new Image();
Highlight4.src = "../img/navigation/schlafen-button-on.png"; /* dritte Highlight-Grafik */

function Bildwechsel (Bildnr, Bildobjekt) {
  window.document.images[Bildnr].src = Bildobjekt.src;
}