function activate(id){
var	img = 'img_' + id;
	imgElement = document.getElementById(img);
	if (imgElement){
		if (imgElement.className == 'hidden'){
			imgElement.className = 'visible';
			}else{
			imgElement.className = 'hidden';
			}
		}
		}
	
function deactivate(id){
var	img = 'img_' + id;
	imgElement = document.getElementById(img);
	if (imgElement){
		if (imgElement.className == 'visible'){
			imgElement.className = 'hidden';
			}else{
			imgElement.className = 'visible';
			}
		}
	}