Instagram said that is adding a new weapon for fighting harassment at the popular mobile app for sharing pictures and videos. The Facebook-owned social network began letting some celebrities and others with accounts that attract torrents of feedback filter those comments by keywords or even turn off the option to comment on particular posts. “Our goal is to make Instagram a friendly, fun and, most importantly, safe place for self-expression,” an Instagram spokesperson said. “As we learn, we look forward to improving the comment experience for our broader community.” If the test goes well, the anti-harassment feature could begin to spread across Instagram in coming weeks. The visually oriented service already allows users to delete comments or use a filter designed to block profanity. Letting users decide which comments to block from their accounts helps take Instagram out of the crosshairs amid complaints about censorship or not doing enough to thwart online harassment. Instagram in June said that its user base has surged to half a billion, adding its latest 100 million in less than a year. More than 80 percent of Instagram users are outside the United States. Instagram, which was acquired by Facebook in 2012, is now seen as a growth engine for Facebook, which has some 1.6 billion users around the world. The social media site has also been ramping up its advertising efforts, which could bring in more revenues for Facebook. According to the research firm eMarketer, Instagram will pull in $1.53 billion in worldwide mobile ad revenue in 2016, a jump of 144 percent over last year.