pic1_u = new Image(350,240);   pic1_u.src = "http://www.isoptik.com/isoptikspn/img/computer_k1.jpg";
pic1_a = new Image(350,240);   pic1_a.src = "http://www.isoptik.com/isoptikspn/img/computer_k2.jpg";
pic2_u = new Image(350,289);   pic2_u.src = "http://www.isoptik.com/isoptikspn/img/bosweg_k1.jpg";
pic2_a = new Image(350,289);   pic2_a.src = "http://www.isoptik.com/isoptikspn/img/bosweg_k2.jpg";
pic3_u = new Image(350,289);   pic3_u.src = "http://www.isoptik.com/isoptikspn/img/kinderen_k1.jpg";
pic3_a = new Image(350,289);   pic3_a.src = "http://www.isoptik.com/isoptikspn/img/kinderen_k2.jpg";
pic4_u = new Image(350,110);   pic4_u.src = "http://www.isoptik.com/isoptikspn/img/chart_k1.jpg";
pic4_a = new Image(350,110);   pic4_a.src = "http://www.isoptik.com/isoptikspn/img/chart_k2.jpg";
pic5_u = new Image(350,198);   pic5_u.src = "http://www.isoptik.com/isoptikspn/img/tv_k1.jpg";
pic5_a = new Image(350,198);   pic5_a.src = "http://www.isoptik.com/isoptikspn/img/tv_k2.jpg";

function img_on(nam) {
  imgoff = eval(nam + "_a.src")
  document.getElementById(nam).src = imgoff
  }

function img_off(nam) {
  imgoff = eval(nam + "_u.src")
  document.getElementById(nam).src = imgoff
  }