With more than 100m users and in excess of five billion photos shared, Instagram needs little introduction. Indeed, the apparent omnipresence of the retro-photo-filtering social networking app has led to countless third-party apps being built atop the Facebook-owned company's API.
One such app is Duelpic, which hit the App Store a few weeks ago, letting Instagram users challenge their friends - as well as random users - to a photo contest using their library of pictures. Who decides? You, me...the whole Instagram community