Take a bottle of vodka from the shelf, slip it past the checkout without paying and what happens? You've been caught in the frame of a closed- circuit TV camera and stored in a digital image bank linked to the supermarket's checkouts, which connect the unpaid-for vodka to your innocent-looking features.
If the managers don't spot you at the checkout, they may spot you the next time you drop in; they may circulate your picture to all the other stores in the group; they may alert whole shopping centres.
This is not the distant future: it is being introduced now by British retailers to combat what, in the trade, they call shrinkage. On the street it is known as "hoisting". Either way, last year more than pounds 650m worth of goods were stolen from British stores by light-fingered customers.
Figures released by the British Retail Consortium confirm that in a year, 1 million offenders were apprehended and passed on to the police, resulting in 140,000 prosecutions. Closed Circuit Television (CCTV) surveillance, initially introduced into high-risk security locations such as building societies and unattended car parks, used electronics to strike a blow against the lawless. But now that the clandestine cameras are on almost every corner and in every high-street shop, security experts are worried that they are losing their deterrent effect.
Science, once more, has come up with an answer: smart spy cameras. By using the latest digital technology linked through fibre-optic cables to powerful computers, security men are able to identify shoplifters before they strike.
One national supermarket chain is introducing the cameras now and others are expected to follow over the next 12 months.
"Digital technology can radically change the way CCTV surveillance works," said David Thomas, marketing director for Orbis Security Systems which is installing the technology in supermarkets all over Britain. "We have linked digital imaging to the supermarket's computerised cash tills in a way that will enable security staff to compile a database of shoplifters who can either be prosecuted or excluded from the store."
The cameras are trained on shelves containing the high-value items most frequently stolen. When a customer takes one of these products off the shelf he will automatically trip an invisible beam which switches on the concealed digital TV camera.
Later, the bar code on those same goods trips another electronic mechanism at the cash register and another hidden digital camera films the shopper's face.
A computer is then used to check out the two images. If, for example, a shopper is seen lifting a bottle of vodka but is not filmed paying for the spirits his picture goes on to a database of suspected shoplifters.
"The system is not necessarily intended to apprehend thieves at the cash till," said Mr Thomas. "What we hope to dois identify the regular shoplifters and ultimately identify them as they enter the premises."
In trials the system quickly revealed advantages over the old, operator- controlled video cameras. "We found that security staff tended to concentrate on individuals they considered the most likely offenders - travellers, new age hippies and so on. In fact we found that many of the most habitual shoplifters were wearing pounds 400 business suits or were ordinary housewives and inoffensive-looking little old ladies," said Mr Thomas.
The digital technology stores clear images on to CD disks that can be searched and cross- checked on computers. Once the new system is fully operational a shoplifter who is discovered pilfering from one branch of a chain of shops could be banned from all the other branches which are able to tap into the rogues' gallery database.
This technology is constrained only by the need of a human operator to match the images. But in as little as two years' time, some experts predict that automatic face mapping will be able to identify shoplifters from cameras sited in the store car parks and track them from the minute they leave their vehicles.
Those concerned with civil liberty issues are worried that the technology could be used to identify and exclude not only shoplifters but environmental protesters, sports fans and political demonstrators.
Dr Clive Norris, a criminologist based at the University of Hull, has studied security surveillance: "Once the image recognition systems are perfected they can be linked to any number of databases and it will be possible for a known shoplifter, or social undesirable, not only to be banned from a specific shop but from all the shops in the chain throughout the country."
And what redress is open to the innocent man or woman in a country where there is no law of privacy and no law specifically dealing with CCTV? The systems being introduced into supermarkets will be covered by the terms governing the Data Protection Act of 1984.
"Under the terms of the Act any individual is entitled to gain access to details of images of themselves that are being held. They are also entitled to know whether they are part of a database," said a spokesman for the office of the Data Protection Registrar.
Information on data protection is available from the Registrar's Office, Wycliffe House, Water Lane, Wilmslow, Cheshire SK9 5AF. Fax 01625 524510.Reuse content