To change the title bar of the popup image, edit /catalog/includes/meta_tags.php.

Find the following code and edit to your liking:

  case CONTENT_POPUP_IMAGE:
    define('META_TAG_TITLE', $products['products_name'] . PRIMARY_SECTION . TITLE . $web_site_tagline);
	define('META_TAG_DESCRIPTION', TITLE . PRIMARY_SECTION . $products['products_name'] . SECONDARY_SECTION . WEB_SITE_KEYWORDS);
	define('META_TAG_KEYWORDS', WEB_SITE_KEYWORDS . $products['products_name']);
    break;