[an error occurred while processing this directive]
BBC News
watch One-Minute World News
Last Updated: Monday, 26 March 2007, 16:30 GMT 17:30 UK
CCTV: The truth, the whole truth?
Mark Shields
CCTV could show the killer, says senior Jamaica investigator
The argument used to be that the camera never lies.

But The BBC News website's Joe Campbell writes that when it comes to evidence that will stand up in court, even industry experts now say the 4.2 million cameras in the UK do not give the whole picture.

Jamaican detectives seeking the killer of Pakistan cricket coach Bob Woolmer are facing problems all too familiar to their British counterparts.

CCTV has come to be seen as a magic bullet, but its effectiveness can be undermined by everything from the age of the equipment, through the positioning of the cameras, to something as simple as the number of times the tapes recording the pictures have been re-used.

Anyone who ever owned a VCR knows how a tape used to record a favourite soap week in, week out, would result in well-known actors becoming increasingly less identifiable as the picture quality declined with each successive recording.

"Fragile" recordings

It is this problem that seems to be uppermost in the mind of the man heading the Woolmer inquiry, Deputy police commissioner Mark Shields, as his team studies CCTV images from outside the hotel room where the killing took place.

They have begun converting the tapes, which were described as being in a "fragile" state, into a digital format.

"It's critically important because it may give us an image of the killer or killers of Bob Woolmer," he said.

It's important we do it right and that's the reason I've got the officers to take their time and examine the tapes and come up with some analysis."

Everyone expects far too much out of CCTV
Peter Fry, CCTV User Group

CCTV cameras may be far more commonplace in Britain, but many in small businesses such as corner shops and petrol stations still rely on similar analogue tape, according to industry insiders.

Peter Fry, Director of the CCTV User Group, which represents more than 500 organisations using the cameras from hospitals to councils, says: "Everyone expects far too much out of CCTV."

One of the organisation's members, who works for a major police force in England, gives the figure of 80% of the images he is asked to examine as being "totally useless" when it comes to relying on them as evidence.

The problem is that a single tape is often used to record the pictures from multiple cameras - producing an image that is a fraction of the size of the actual TV screen.

Even with digital systems, where the individual feeds can be separated off, some recorders store too little information for the picture to be blown up to a useable size before the image disappears into a mass of dots - a problem all too familiar to anyone who has ever tried to zoom in on a picture on their computer screen.

Poor quality images

"Much of the equipment being sold was never intended for such commercial use and comes from home entertainment manufacturers looking for new markets," says Peter Fry.

"Also the material cannot be downloaded to another format such as DVD and that means the police have to remove the entire hard-drive as evidence."

Digital technology has meant a huge leap in the number of images that can be stored. But that in itself has become a problem.

Officers investigating the 7/7 London bombings went to seize material from one local authority to be confronted by a stack of DVDs 16 feet high, according to one insider.

July 7 bombers on CCTV
The July 7 bombings produced a mountain of CCTV images

The inquiry also highlighted the poor quality of images from many systems and the Home Office and Association of Chief Police Officers have been looking at how to address the problem.

A report, due out shortly, is expected to lay down new industry standards for those using cameras.

Wrong identification

Even when high quality images exist, and more importantly are located by detectives who have studied hundreds of hours of CCTV, questions remain about how useful they are at actually identifying suspects.

Academic research has shown that when people were given a still picture of somebody and asked to pick them out of a series of CCTV stills, they picked the wrong person or could not find them at all in 30% of cases - and that was when the two pictures were taken in identical lighting conditions with the subject displaying a similar facial expression.

Better quality images from newer digital systems have the potential to make CCTV more useful in court, according to Michael Bromby of the Centre for Forensic Statistics at Glasgow Caledonian University.

But he also sounds a warning.

"If you get a DVD and stick it on your telly then it can do all sorts of things to the person's face before it decodes the signal properly and that's where you're working with a limited number of broadcast standards.

"You have to accept that the camera and computer are doing something to compress and store the image which can alter it.

And that matters where somebody is saying this is or isn't the person, when you look at the ratio of the distance between their eyes or from their nose to the chin," he explains.

Right place

Before the lawyers and experts can even begin those arguments though, the camera has to capture an image.

Annie Freeman
Pensioner Annie Freeman's hat threatened to thwart CCTV

The case of Annie Freeman, an 87 year old pensioner ordered to remove her hat when she popped into a pub in Aldershot so as not to hide her face from CCTV cameras, shows how it does not take hi-tech tricks like those used by crooks in the film Ocean's 11 - to foil the security systems.

More often though, it comes down to the cameras simply not being in the ideal place - as police in Jamaica may now be finding.

Dr Andrew Adams of the University of Reading cites the case of a colleague who is working on cameras designed to spot potential terrorists, who had his car broken into on campus.

"Within 20 minutes he went to security staff with a description of some youths he'd seen hanging around the car park, only to find that despite all the signs warning of CCTV surveillance, not one had been pointing in the right direction to catch the suspects."

Woolmer police study hotel tapes
25 Mar 07 |  Americas
Woman, 87, removes hat for CCTV
22 Feb 07 |  Dorset

The BBC is not responsible for the content of external internet sites

Has China's housing bubble burst?
How the world's oldest clove tree defied an empire
Why Royal Ballet principal Sergei Polunin quit


Americas Africa Europe Middle East South Asia Asia Pacific