function jsDoImg(imgname, ext)
{
	var big = 0;
	var z = document.images[imgname].src.lastIndexOf("_tn.")
	if(z >= 0) {
		big = 1;
	}

	var img = '';
	var alt = '';
	if(big) {
		img = imgname+"."+ext;
		alt = "Click to reduce";
	} else {
		img = imgname+"_tn."+ext;
		alt = "Click to enlarge";
	}
	document.images[imgname].src = img;
	document.images[imgname].alt = alt;

	if("undefined" != typeof(jsOnResizeImg)) {
		jsOnResizeImg(imgname, big);
	}

    return false;
}