Who needs human actors? As digital characters become more real, advances in technology threaten to make actual people obsolete in Hollywood. (arts).

Thanks to digital technology, seeing is no longer believing in movies, even to the tiny degree it once was.

Not-really-there computer-generated characters are popping up more and more. Films this spring will feature a new crop, including the crime-fighting cartoon dog of Scooby-Doo, the swinging stunt double in Spider-Man, and the much-hated Jar Jar Binks in Star Wars: Episode--II Attack of the Clones.

Filmmakers may soon be faced with their own version of the cloning debate. When computer graphics imaging (CGI) becomes detailed enough, and when voice synthesis software becomes smooth enough, the next crop of such characters could look and sound more realistic, maybe even passably human. But is it right to create humans out of pixels?

A new film is expected to confront the issue of cyberstars. Titled Simone and set for release later this year, it's the story of a down-and-out movie producer, played by Al Pacino, who creates a digital replacement when a temperamental actress walks out in the middle of filming. The replacement--named Simone, or Sim(ulation) One--becomes an overnight sensation, requiring Pacino's character to maintain the fiction that she is real--something that will certainly pose a problem at press conferences and awards banquets.

It is telling,, however, that Simone will reportedly be played by an unknown actress rather than a character from digital scratch, though the studio, New Line Cinema, is keeping plans under wraps. Existing technology can present a semi-plausible human figure, like Dr. Aki Ross, the heroine with skin pores and split ends from last year's all-CGI movie Final Fantasy. But it is not yet advanced enough to simulate the indescribable energy that passes from an actor on the screen to a viewer in a movie theater. For the moment, if a filmmaker wants a spectator to identify with a character, it's safer to begin with organic matter than a cloud of numbers.

CARTOON WORLDS VS. REALITY

CGI has so far been at its best when rendering monsters, dinosaurs, and cartoon-like people. The completely digital Shrek was one of the biggest hits of 2001. The more realistically styled Final Fantasy bombed, as the digital humans contributed to the cold, sterile feel of the film.

Maybe the ogre Shrek was more accepted than Dr. Aki Ross because today's CGI processes are nothing more than technologically advanced versions of traditional animation techniques, with the computer replacing the drawing board.

CGI animations have also been successfully used alongside real-life actors, if not necessarily in place of them. Director Steven Spielberg brought modern CGI to its maturity in 1993 with Jurassic Park, as digital dinosaurs attacked people.

Of course, it is one thing to animate a raptor, something else to animate, say, Tom Hanks. The human movie star isn't thrilled with the prospect. "I am very troubled by it," Hanks says. "But it's coming down, man. It's going to happen. And I'm not sure what actors can do about it."

Still, even if the technology existed to create a perfect computer model of Hanks, who would inhabit it and bring it to life? In cartoons, that role would fall to the director or supervising animator; presumably, the same would be true of the synthetic cinema of the future. It would result in something closer to a puppet show, in which all of the performers are manipulated by a single person--the man behind the curtain.

Director George Lucas has shown this way doesn't quite work. Three years ago, in Star Wars: Episode I--The Phantom Menace, he introduced Jar Jar Binks, the first digital actor with a major role in a live-action film. Jar Jar exhibited Lucas's worst instincts for cutesiness and fussiness. The character became abhorred, spawning Web sites such as www.jarjarmustdie.com. Jar Jar's role is reportedly much reduced in this May's Episode II.

Lucas has acknowledged the limits. "I believe that I have used more digital characters than anyone," he says. "But I don't think I would ever use the computer to create a human character. It just doesn't work. You need actors to do that."

HUMANS AS PROGRAMS

There are more aspects to a screen persona--or to any human presence--than a look. Software will never generate star quality--the combination of gestures, impulses, and details that bring a sense of life to a character. Says visual-effects expert Andre Bustanoby of one such attempt, "The problem with human faces is that you get just a little bit off, and it immediately becomes very disturbing."

But technology is progressing rapidly. New speech generation software could replicate human voices to go along with improved digital bodies.

In the end, we will likely come to accept cyberstars as one of the countless illusions that make up a movie. Films function because of our willing suspension of disbelief; artificial actors are no different. They come to life only if we really, really want to believe in them.

With reporting by RICK LYMAN of the Times.