请教joomla中文章里的参数是怎样获取的？

请问joomla中文章里的参数是怎样获取的？？？
images字段中的数据是：
{"image_intro":"images\/image1.jpg","float_intro":"","image_intro_alt":"","image_intro_caption":"","image_fulltext":"","float_fulltext":"","image_fulltext_alt":"","image_fulltext_caption":""}

$db = & JFactory::getDBO();

$query="SELECT * FROM #__content ORDER BY publish_up DESC LIMIT 0,7";

$db->setQuery($query);

$rows = $db->loadObjectList();

foreach($rows as $row){

    echo $row->images . '
';   //这样只能显示整个字段的内容

}

我想只输出images字段中image_intro里的内容（也就是images/image1.jpg），应该怎么写？？？
谢谢！！！
------解决方案--------------------
$json = json_decode($row->images);
echo $json->image_intro;