function imgswap() {
	if (document.getElementById && document.getElementsByTagName && document.createTextNode) {
		var tmbs = document.getElementById('tmb_pics');
		var as = tmbs.getElementsByTagName('a');
		for (var i = 0; i < as.length; i++) {
			as[i].onclick = function() {
				bb = this.getAttribute("id");
				alt= this.firstChild.getAttribute("alt");
				show(this);
				return false;
			}
		}			
	}
}

function show(s) {
	var mainimg = document.getElementById('main_pic');
	mainimg.innerHTML = "<img src=\"images/fullimg"+bb+".jpg\" alt=\""+alt+"\" />";
}
window.onload = imgswap;