Toei Animation, Hitachi and Toei Chemical Industry have jointly developed a technique for digitally colouring black-and-white animated films - a first for the Japanese film industry.

Toei Animation researchers have successfully used the technique to colour part of an episode of Wolf Boy Ken, a 1963 Toei cartoon series.

After cleaning the original film, researchers transferred it frame by frame to a computer. They then separated the background and animated portions of the image on the computer screen and coloured each one.

In addition to reviving classic cartoons for today's audiences, the technique will be useful for preserving quickly deteriorating film stock, Toei officials said. The digitalised images can also be used in the production of 3D films and computer games.

Toei Animation, the largest film studio in Asia, was founded in 1956 to provide local competition to American animation. It produced hundreds of hours of black-and-white cartoons before converting all production to colour in the 1960s.