A facial recognition system is a computer application to automatically identify or verify a person from a digital image or a frame from a video source.

But despite decades of research into the technology, experts say they have still to overcome some problems with facial identification.

Zheng Nanning, a top artificial intelligence scientist and member of the Chinese Academy of Engineering, said, "A cutting-edge study is looking at facial identification in an uncontrolled environment, for example, outdoor applications, using time-elapsed photos, and recognition from large crowds."