function switchLayers(image,name) {
                                 var elem = document.getElementById(name);
                                 //alert(name + ": " + elem);                            
                                 if( elem.style.display == "none" || elem.style.display == "") {
                                     elem.style.display = "block";
                                     image.src = ""; 
                                                                 
                                 } else {
                                     elem.style.display = "none";
                                     image.src = '';
                                 }
}