Face off

Tagging friends manually in Facebook photographs can be a bore, especially for people who are trigger-happy with their cameras. So the world's most popular social networking site introduced a new feature: a computer programme that can gather information about people's faces and recognise them automatically in new pictures - a useful time-saver.

This is just one use of an increasingly popular technology. Face recognition is now being used for security - to unlock some AndroidA robot that looks like a human being (in science fiction).  phones, for example. Another smartphone app uses face recognition with cameras in clubs and bars to tell potential customers the average age of the people inside - and how many of them are girls. Special face-scanning electronic billboards will be appearing this month in several major cities. They will analyse the faces of passers-by to decide which sort of advert they should be shown, based on age, gender and attention levels.

For business leaders, this sort of approach has a lot of potential. But the rapid development of the technology has campaigners worried. As a recent experiment showed, it is extremely easy, once you plug someone's face into a facial recognition programme, to find out much more about them than their age. Comparing facial data to information online could give you someone's full identity, hobbies, credit rating and perhaps even home address. That information, captured by a camera inside a billboard, could be beamed anywhere.

In principle, campaigners say, we are now getting close to a world were computer programs can use the CCTVShort for closed circuit television. Video camera used to monitor areas for security.  cameras scattered around cities to track all of us wherever we go. It is no surprise then that among the most enthusiastic customers for face recognition programmes are police forces.

A small backlash is already beginning. Officials in Germany are now preparing to take Facebook to court, accusing it of breaking the law by failing to tell users clearly when it began gathering facial recognition information earlier this year.

Are such privacy worries just paranoia? The internet means we all now leave huge trails of data behind us whatever we do online - but that data is not used to harm us. By and large, it makes life better (or at least makes for more interesting adverts). Face recognition is just the same thing transferred to the real world. It could also have really useful applications like identifying criminals or finding lost children.

Face recognition is a step too far, campaigners reply. It could strip us of the anonymity we enjoy in crowds - as part of protests for example. It puts too powerful a tool into the hands of governments and police, a tool that could one day be used to destroy personal freedom.