if(document.images) {
  
	var bookon = new Image();  
	var bookoff = new Image();
	var memoiron = new Image();
	var memoiroff = new Image();
	var songon = new Image();
	var songoff = new Image();
	
	bookoff.src = "images/sf_book_off.gif"
	bookon.src = "images/sf_book_on.gif"
	memoiroff.src = "images/sf_memoir_off.gif"
	memoiron.src = "images/sf_memoir_on.gif"
	songoff.src = "images/sf_song_off.gif"
	songon.src = "images/sf_song_on.gif"
}


function off(imgName) {
	if(document.images) {
	document[imgName].src = eval(imgName + 'off.src');
	}
}

function on(imgName) {
	if(document.images) {
	document[imgName].src = eval(imgName + 'on.src');
	}
}