. Professor Acquisti says social networks like Facebook and LinkedIn represent some of the world's largest databases of identities. He sees increasing threats to privacy in facial recognition software and cloud computing -- the ability to store huge amounts of information in data centers. "The convergence of all these technologies -- face recognition, social networks, cloud computing -- and all these advances in ... data mining are creating this world where you can blend together online and offline data. You can start from an anonymous face and end up with sensitive inferences about that person." Recognition systems measure things like the size and position of a nose, the distance between the eyes and the shape of cheekbones. The software compares lots of images to try to identify the person. Facial recognition programs are used in police and security operations. But the software is increasingly popular in other uses, including social media sites.For the study, the Carnegie Mellon team used software from Pittsburg Pattern Recognition, or PittPat. Google bought that company last month. The software can recognize faces in photos and videos.