function popup_image(img_name, img_width, img_height) {
var left = (screen.width - img_width)/2;
var top = (screen.height - img_height)/2;
win = window.open("","win","width=" + img_width + ",height=" + img_height + ",left=" + left + ",top=" + top + ",scrollbars=auto");
win.document.open();
win.document.write('Detailansicht');
win.document.write('');
win.document.write('');
win.document.close();
win.focus();
}