//preload der Images
function loadPicturesOnStart() {
        if(document.images){
                document.pictureArray = new Array();
                var i;
                var j = document.pictureArray.length;
                var names = loadPicturesOnStart.arguments;
                for(i = 0; i < names.length; i++) {
                        document.pictureArray[j]=new Image;
                        document.pictureArray[j].src= names[i];
                        j++;
                }
        }
}

function swapPictures(pictureName, einaus) {
         if (einaus) {
             document.images[pictureName].src = "img/" + pictureName + "_m.jpg";
         } else {
             document.images[pictureName].src = "img/" + pictureName + "_u.jpg";
         }
}