var objCount = 0;

    function preload(name, first, second) {

      // preload images and place them in an array

      if (browserOK) {
        pics[objCount] = new Array(3);
        pics[objCount][0] = new Image();
        pics[objCount][0].src = first;
        pics[objCount][1] = new Image();
        pics[objCount][1].src = second;
        pics[objCount][2] = name;
        objCount++;
      }
    }

    function on(name){
      if (browserOK) {
         for (i = 0; i < objCount; i++) {
          if (document.images[pics[i][2]] != null)
            if (name != pics[i][2]) {
              // set back all other pictures
              document.images[pics[i][2]].src = pics[i][0].src;
            } else {
               // show the second image because cursor moves across this image
               document.images[pics[i][2]].src = pics[i][1].src;
            }
        }
      }
    }

    function off(){
      if (browserOK) {
         for (i = 0; i < objCount; i++) {
          // set back all pictures
          if (document.images[pics[i][2]] != null)
            document.images[pics[i][2]].src = pics[i][0].src;
        }
      }
    }

    preload("link1", "all_img/M_Ems_1.gif", "all_img/M_Ems_2.gif");
    preload("link2", "all_img/M_pt_1.gif", "all_img/M_pt_2.gif");
	preload("link3", "all_img/M_Kunstst_1.gif", "all_img/M_Kunstst_2.gif");