Demotix, the photo agency created to distribute and sell newsworthy images from members of the public, has been bought by image giant Corbis. London-based Demotix, which has smartphone apps to make it easier to submit images, has a community of around 6,500 freelancers and semi-pro photographers and videographers submitting work. By contrast, Seattle-based Corbis’s collection of 100 million images tends to come from professionals and it more tightly curated.