Q the big clean-up

'Come in Mr Bond. Your latest mission is to take 70km of film, shot over more than 40 years, remove 37 million pieces of dirt, 2,812 metres of scratches and 74,000 hairs, to make it all look as though it was filmed over the past month.'

It sounds like the kind of task even Tom Cruise would find impossible. But it's one MGM wanted accomplished so that it could restore every one of the James Bond films for DVD release before the latest instalment, Casino Royale, hits cinemas in November.

Bond historian John Cork calls the project 'the biggest job on the biggest film franchise ever'. The agents charged with the task were the Californian digital restoration firm DTS Digital.

Formerly known as Lowry, the company's first restoration project was North By Northwest in 2000. It took two people using 12 Apple G4s six months to complete. In the following years, the techniques used became so sophisticated, the Bond job used 600 dual Apple G5s, each with 4Gb of RAM. The whole project took more than 30 months with most of the DTS staff on board.

According to Michael Inchalik of DTS, the Bond mission reaches levels never before achieved. 'Before this job, the original Star Wars trilogy was widely considered as the high watermark in digital restoration,' he says. 'But this job takes things to a totally new level.'

The DTS process has five steps:

Inspection: The firm starts with the original camera negative where possible and inspects every single frame. 'There were 37million of them on the Bond films,' says Inchalik. 'The film is an extremely valuable asset and, before we put it through a transporter for digitising, we had to make sure it would not suffer in any way. We fixed all torn sprocket holes and splices in a traditional filmic way.'

Scanning: Film is scanned using Imagica 4K film scanners - regarded as the 'Cadillac of handling old films'. Each film has some 190,000 images at 45Mb each. To handle capacity, DTS used a 700Tb storage facility (a terabyte is one million million bytes).

Automatic image processing: All images are colour corrected and as many defects removed as possible. 'It's a complicated automatic process,' says Inchalik. 'There are 1,200 processors at work and, when an image has been corrected, the computer is programmed to hold up its hand and ask for another frame to process.' Film grain - the small dots that make up the image and which are inherently large in older films - is the biggest problem, according to Inchalik. 'Take it out and you discover more problems underneath as most of the image detail is hidden under the grain,' he says.

Manual processing: Automatic processing can only correct so many problems and can only do so with images that are panning. 'A computer will look at the immediately previous or following frames and be able to work out what is behind a crack or a hair,' he says. 'But with a stable image, the computer has no information as to what is behind the defect, so a team of graphic artists takes over.' Each frame is again inspected and corrected using proprietary software similar to an advanced version of Photoshop.

Quality control: This is followed by downsampling for films to be put on various formats. New film negatives are also created from stock with a life expectancy of 150 years.

Some archival purists believe the original films should not be compromised in any way but Douglas McFarlane of website UKFilm.TV disagrees. 'It's the same with moving away from any old medium,' he says. 'We have an emotional connection to seeing or hearing a fantastic film or bit of music and it's sometimes not easy to let go. But I'm excited about this restoration. It will be like seeing a totally new set of films.'

But will technological capacity increase again, meaning people who buy one of the new DVDs have to upgrade it again in a few years? 'Scanning the films at 4k means every pixel is only 6microns square,' says Inchalik. 'That is a quarter of the size of the film grain which is the capture medium. We've managed to get every piece of information out of the films possible. Even if we are looking at 16k display screens in 20 years' time, these films could never get to that level of sharpness.'

It seems Bond is back. And this time, he really is better than ever.

The Bond Ultimate Edition DVDs are released on Monday.