function popup(file)
{	
	var width = 710;
	var height = 540;
	var left = (screen.width - width) / 2;
	var top = (screen.height - height) / 3;
	var windowAttributes = 'width='+width+',height='+height+',left='+left+',top='+top+',scrollbars=no,location=no,toolbar=no, resizable=yes';
	
	var href = 'img/' + file;
	
	window.open(href,'_blank',windowAttributes);
}