Move over Mickey, here comes the microprocessor

Animation is the simplest form of film-making. All it takes is a pencil and paper. But with a million or more drawings in a cartoon feature film, each of which then has to be painted by hand, it is hard work. Now, however, the pencil has turned electronic and computers are beginning to take over toontown.

Steven Spielberg is the latest of Hollywood's big names to move into computerised animation at his new studio, DreamWorks, which is working on its first cartoon feature, Prince of Egypt.

The system he chose is British, Animo, from Cambridge Animation, and it can run on an ordinary PC.

Now, if the animation skills are there, anyone can produce their own cartoon in their spare time. For Michel Gagne, the highly skilled head of special effects at Warner Brothers, it is not surprising that his dazzling short film Prelude To Eden should be wonderful. What is surprising is that it was created on his home PC, a 60MHz Pentium.

Others using Animo include the British Oscar-winning cartoonists Snowden Fine, Warner Brothers and the makers of many television series, such as The Animals of Farthing Wood, Mr Men and Fantom Cat. It is also being used by games software companies.

Even with the help of a computer, animation requires great skill. Artists still do all the drawings on paper, then scan them in and do the animation, composition and painting in the computer. It is possible to draw the keyframes on paper, turn them into vectorised models in the computer and have it automatically generate the in-between shots. But telling the computer what to do can take as long as doing it yourself. Most animators prefer to do the creative work by hand and leave the drudgery to the computer.

Where computers score is in instantly creating special effects - usually these have to be produced in a dedicated lab - and in their ability to do incredible multi-plane shots, which even the best camera could never achieve.

Because acetate, on which cartoons are traditionally drawn, has a slight green tinge, it is only possible to shoot through about seven layers before it becomes too green, whereas computers can cope with infinite layers.

These systems are not cheap. The basic Animo Studio costs pounds 10,000 for the software, plus pounds 8,000 upwards for a fully equipped PC. Alternatives such as Animo's main rival, Toonz, from Softimage, part of the Microsoft empire, cost about the same. There are also several impressive systems produced in France, where the government has injected millions into their development.

There is another option, 3D, as used in Disney's Toy Story, the first feature film completely generated using a computer. It is better suited to computerisation because once the animator has built a model of a character in the computer, it can be moved as if it were solid. But the results in cartoons are mixed.

Animators at Cambridge Animation say the future will be some sort of hybrid 2D/3D system. They are working on one themselves, although the first hybrid system is likely to come from Newtek. It is best known for its pounds 400 LightWave 3D animation system, which produced the space scenes in Babylon 5 and the latest Star Trek spin-offs.

Newtek is now developing tools to allow LightWave to produce images with a 2D animation look. Being a development of a 3D platform should also make it easier for users to change camera angles, as the camera already moves in 3D. The software will produce contour lines automatically, so that they look as if they were drawn in 2D by an artist.