function randomImage() {
	//random image
	var imagesArr = new Array();
	imagesArr[0] = "home.jpg";
	imagesArr[1] = "home_2.jpg";
	
	//replace header with random image
	var rootDir = "images/large_images/";
	var imageIndex = Math.floor( Math.random()*imagesArr.length );
	document.getElementById("headerImage").src = rootDir + imagesArr[imageIndex];
}