if (document.images) {
            img1on = new Image(); 
            img1on.src = "/pictures/tema/tema1b.jpg";
			img2on = new Image(); 
            img2on.src = "/pictures/tema/tema2b.jpg";
			img3on = new Image(); 
            img3on.src = "/pictures/tema/tema3b.jpg";
			img4on = new Image(); 
            img4on.src = "/pictures/tema/tema4b.jpg";
								                        			
			img1off = new Image(); 
            img1off.src = "/pictures/tema/tema1a.jpg";
			img2off = new Image(); 
            img2off.src = "/pictures/tema/tema2a.jpg";
			img3off = new Image(); 
            img3off.src = "/pictures/tema/tema3a.jpg";
			img4off = new Image(); 
            img4off.src = "/pictures/tema/tema4a.jpg";
			
			}
			
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");
        }
}