Belfast may be a city with a troubled past, but according to a new iPhone app using technology that can analyse people's faces in Instagram photos, it's the UK's happiest.

Bournemouth, Derby, Exeter and Lincoln complete the rest of the top five.

The study, which used new "geo-parsing" technology to find patterns in over 100 million public images on Instagram, shows that among cities in the UK, Belfast leads the way with the highest “smile score,” a value based on the average size of smiles in photos.

Jetpac City Guides is the new app behind the study, and it works by curating Instagram's big data to help travellers find local sights, bars and cool places to hang out.

It examines every pixel of more than 100 million photos, encompassing more than 5,000 cities.

Talking about analysing the pictures on Instagram, CEO Pete Ward said when looking at the smile on a person's face: "We want to know if people are having a good time at this cafe, and smiles are a good sign that they are. (When) we do spot a small smile, it gets a score of about 20 on our 0 to 100 scale."

Do you agree with the results?

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Earlier on HuffPost:

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  • David Brooks

    New York Times columnist David Brooks got an unlikely start to his career as a writer, author and political commentator. He began writing a humor column for the school paper in his junior year at the University of Chicago. During his senior year, when he learned that author William F. Buckley was visiting the campus, Brooks sent the author a parody of his memoir, <em>Overdrive</em>, <a href="http://nymag.com/news/media/67010/index4.html" target="_blank">New York magazine reports</a>. Brooks added a note that read: “Some would say I’m envious of Mr. Buckley. But if truth be known, I just want a job and have a peculiar way of asking. So how about it, Billy? Can you spare a dime?” Buckley announced during his lecture in Chicago the next week, "David Brooks, if you’re in the audience, I’d like to give you a job." Unfortunately, Brooks wasn't there -- he had been selected to participate in a debate tournament in California that day -- but he quickly launched a successful career in journalism after college nonetheless.

  • Sally Field

    Sally Field may be an Oscar-winning actress, but she still had to fight to land a role she knew was meant for her, playing Mary Todd Lincoln, Abraham Lincoln's wife, in the 2012 film, "Lincoln." The actress fought hard to convince director Steven Spielberg (who originally <a href="http://www.youtube.com/watch?v=JVizVfzSqEI" target="_blank">said</a> he knew she was "not right") and leading man Daniel Day-Lewis that she was the one for the part. Following an initial screen test -- after which Spielberg refused her for the role -- Field convinced Day-Lewis to fly to Los Angeles from Ireland for the day to improv with her in full costume for Spielberg. She nailed it -- and the rest is history. "To actually become Mary, I had to demand that they didn't walk away," <a href="http://www.youtube.com/watch?v=5uBqUM6RfjQ" target="_blank">Field told Good Morning America</a>.

  • Anderson Cooper

    Anderson Cooper <a href="http://www.biography.com/people/anderson-cooper-20851303" target="_blank">began his media career</a> as a fact-checker for Channel One, which produces news shows to be broadcast in schools. But the ambitious Cooper -- who had just received his degree in political science from Yale -- got bored with the position pretty quickly. Rather than resigning himself to the daily grind, Cooper took his video camera to Southeast Asia, where he filmed scenes of strife in Myanmar and then parts of Africa. The stunt quickly earned him the position of chief international correspondent for Channel One, and ultimately caught the attention of ABC News, where he landed his first job as an anchor.

  • Michael Lewis

    Best-selling author and business journalist Michael Lewis has made a career out of uncovering the dark secrets of Wall Street. But he wasn't always getting bylines on cover stories for Vanity Fair and The New York Times -- Lewis was still in the London banking world when he started writing articles satirizing it. His first piece for The New Republic ("It was basically just making fun of British bankers," Lewis said) was a PR nightmare for his firm Salomon Brothers. But it didn't stop him: Lewis continued writing articles using his mother's name, Diana Bleeker, as a pseudonym. Soon enough, "Diana Bleeker" got a contract with Business Magazine -- meaning Lewis could leave his job to pursue his passion. "It became clear I could make a living -- if not as fancy a living -- as a writer," <a href="http://www.publishersweekly.com/pw/print/19991018/32870-michael-lewis-seeking-the-soul-of-silicon-valley.html" target="_blank">Lewis told Publishers Weekly</a>, "and so I quit."

  • Amy Tan

    Before Amy Tan was a bestselling author, she ran a technical-writing business with a partner, focusing largely on account management. Feeling stifled and unfulfilled in her position, Tan shared with her partner that she wanted to do more writing, <a href="http://www.rd.com/advice/work-career/how-famous-people-achieved-their-dreams/" target="_blank">Reader's Digest reported</a>. But he told her to keep doing what she was "most good at" -- chasing down contractors and collecting bills, her least favorite part of the job -- and that writing was her weakest skill. She fought back repeatedly, and when her partner refused to acknowledge her skill, Tan ultimately quit. She took on a heavy load of freelance assignments, and went on to write a handful of best-selling novels.

  • Debbie Wasserman Schultz

    As a recent college graduate, aspiring politician Debbie Wasserman Schultz helped Florida congressman Peter Deutsch successfully run for the U.S. House of Representatives -- and then got his blessing to go after his seat in the Florida House of Representatives. Wasserman Schultz went from neighborhood to neighborhood, personally knocking on the doors of more than 25,000 people in her home state of Florida to win the seat. She became the youngest female legislator in the state's history at just 26 years old, <a href="http://www.businessinsider.com/what-successful-people-did-in-their-20s-2013-3?op=1#ixzz2c3H9zRay" target="_blank">Business Insider reports</a>.

  • Chris Putnam

    Facebook founder and CEO Mark Zuckerberg lives by the maxim "Fortune favors the bold" -- and perhaps none of his employees at Facebook personify that idea more than Chris Putnam. In 2005, the young tech whiz <a href="http://www.businessinsider.com/how-i-attacked-facebook-with-a-virus-and-got-a-job--at-facebook-2011-2" target="_blank">hacked the site </a>and wrote a computer virus to make user profiles look like MySpace pages. The hack lasted less than a day, but it caught the attention of COO Dustin Moskovitz, with whom Putnam developed a relationship via Facebook message and AIM. Soon afterwards, Putnam received an offer from Facebook, dropped out of college in Georgia, and moved to Silicon Valley to join the team. With Facebook's founding ethos of risk-taking, it's not surprising that the company decided to hire Putnam. As Zuckerberg <a href="http://www.cbsnews.com/8301-505125_162-28248860/facebooks-mark-zuckerberg-insights-for-entrepreneurs/" target="_blank">once said</a>, "The biggest risk is not taking any risk. In a world that changing really quickly, the only strategy that is guaranteed to fail is not taking risks."