var base = "images/";
if (document.images) {
        img1on = new Image();   img1on.src = base + "home_on.gif";
        img2on = new Image();   img2on.src = base + "corporate_on.gif";
        img3on = new Image();   img3on.src = base + "product_on.gif";  
        img4on = new Image();   img4on.src = base + "photo_on.gif";
        img5on = new Image();   img5on.src = base + "contact_on.gif";
        img6on = new Image();   img6on.src = base + "about_on.gif";

        // Inactive images
        img1off = new Image();   img1off.src = base + "home_off.gif";
        img2off = new Image();   img2off.src = base + "corporate_off.gif";
        img3off = new Image();   img3off.src = base + "product_off.gif";  
        img4off = new Image();   img4off.src = base + "photo_off.gif";
        img5off = new Image();   img5off.src = base + "contact_off.gif";
        img6off = new Image();   img6off.src = base + "about_off.gif";
        }
        
        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");        
            }
    }