if (document.images) {

 homeon = new Image ();
 homeon.src = "images/home-on.png";
 homeoff = new Image ();
 homeoff.src = "images/home-off.png";
 
 programon = new Image ();
 programon.src = "images/program-on.png";
 programoff = new Image ();
 programoff.src = "images/program-off.png"; 
 
 referenceson = new Image ();
 referenceson.src = "images/references-on.png";
 referencesoff = new Image ();
 referencesoff.src = "images/references-off.png"; 

 testimonialson = new Image ();
 testimonialson.src = "images/testimonials-on.png";
 testimonialsoff = new Image ();
 testimonialsoff.src = "images/testimonials-off.png";
 
 newspaperson = new Image ();
 newspaperson.src = "images/newspapers-on.png";
 newspapersoff = new Image ();
 newspapersoff.src = "images/newspapers-off.png"; 
  }
function turnOn(imageName) {
     if (document.images)  {
           document[imageName].src = eval(imageName + "on.src");
         }
     }
function turnOff(imageName) {
     if (document.images) {
           document[imageName].src = eval(imageName + "off.src");
        }
    }