imgOn = function(imgId) {
	var theimage = document.getElementById(imgId);
	var imgType = /(\.gif|\.jpg|\.png)/;
	theimage.src=theimage.src.replace(imgType, "_on$1");
}

imgOff = function(imgId) {
	var theimage = document.getElementById(imgId);
	var imgType = /(_on)(\.gif|\.jpg|\.png)/;
	theimage.src=theimage.src.replace(imgType, "$2");
}