if (document.images) {

img1on = new Image();
img1on.src = "img/tnav/gmbh_h.jpg";
img1off = new Image();
img1off.src = "img/tnav/gmbh.jpg";

img2on = new Image();
img2on.src = "img/tnav/digiprint_h.jpg";
img2off = new Image();
img2off.src = "img/tnav/digiprint.jpg";

img3on = new Image();
img3on.src = "img/tnav/printline_h.jpg";
img3off = new Image();
img3off.src = "img/tnav/printline.jpg";

img4on = new Image();
img4on.src = "img/tnav/printet_h.jpg";
img4off = new Image();
img4off.src = "img/tnav/printet.jpg";

img5on = new Image();
img5on.src = "img/tnav/etipro_h.jpg";
img5off = new Image();
img5off.src = "img/tnav/etipro.jpg";

img6on = new Image();
img6on.src = "img/tnav/artpack_h.jpg";
img6off = new Image();
img6off.src = "img/tnav/artpack.jpg";
}

function imgOn(imgName) {
if (document.images) {
document[imgName].src = eval(imgName + "on.src");}
}
function imgOff(imgName) {
if (document.images) {
document[imgName].src = eval(imgName + "off.src");}
}