Technology faces up to a question of identity(2)

The technology's application in civil use, for events such as concerts, means the greater accuracy can be compromised and costs reduced.

"As a result, civil-use facial recognition devices are far cheaper than those used for security, both in terms of hardware and software," Zheng said.

"Generally a new technology is often limited to military or security applications at the initial stage. But as it becomes popular, the price drops."

The price to develop a facial recognition system is low enough for the professor's roll call.

"In March 2011, I was teaching two courses, both related to face-recognition theory," Wei said.

"So I thought, Why not develop a system for the class, so that the students will have an intuitive feeling for the technology?"

Developing such a system took only a month for Wei and four members of a research team. Operating costs are merely renting a server for a roll-call website.

The system can be set up in easy stages. First, the lecturer takes photos of the whole class from different angles. Then the computer analyzes the photos, and "recognizes" the faces. The third step involves students giving details, such as age and class number.