function change_th1(){
	document.getElementById("preview").style.background = "url(Photographs/testimage_fu.jpg)";
	document.getElementById("preview").style.Zindex = "2000";
}
function change_th2(){
	document.getElementById("preview").style.background = "url(Photographs/testimage_fu.jpg)";
	document.getElementById("preview").style.Zindex = "2000";
}

function change_back(){
	document.getElementById("preview").style.Zindex = "-2000";
}

function mypopup(imgurl, width, height) {
	var attributes = "menubar=0, resizeable=0, scrollbars=0, width=";
	width = width + 20;
	height = height + 20;
	attributes = attributes + width;
	attributes = attributes + ", height=";
	attributes = attributes + height;
	
   	mywindow = window.open (imgurl, "",attributes);
}