function open_centered_popup(image, width, height) {
	x = (640 - width)/2;
	y = (480 - height)/2;
	if (screen) {
		y = (screen.height - height)/2;
		x = (screen.width - width)/2;
	}
	window.open('zoom.php?img='+image,'n3xt_portfolio_zoom','width='+width+',height='+height+',screenX='+x+',screenY='+y+',top='+y+',left='+x+',scrollbars=no,resizable=no');
}