var alreadyRun = false;
function randomimage() {
   	if (alreadyRun) { return; }
   	alreadyRun = true;
        var p = 6;  // Set the number of images to be randomized
	var whichImage = Math.round(Math.random()*(p-1));
	document.getElementById('banner-wrapper').style.backgroundImage="url(http://www.iml.uts.edu.au/images/css/splash-main-graphic" + (whichImage+1) + ".jpg)";
}