function change_back_img(page)
{
	var back_div = document.getElementById("mainPage");
	var img = "";
	switch (page){
		case "index":
			img = "front_image.jpg";
			break;
		case "about":
			img = "basepic_aboutus.png";			
			break;
		case "viewproduct":
			img = "";
			break;
	}
	back_div.style.backgroundImage = "url(images/"+ img +")";
}

function tellFilename()
{
	montage=window.location.href.split("/");
	simple=montage.length-1;
	return montage[simple];
}