Three-dimensional films, once blamed for making audiences nauseous, are making a comeback and are likely to become the future of cinema thanks to digital technology, Hollywood studio moguls say.

The latest advances have enabled studios to use special effects and state-of-the-art projectors to create 3D films far superior to their predecessors, they said at the 3DX Festival in Singapore this week.

"In the history of film, there have been two great revolutionary events -- the transition from silent movies to synchronised sound that happened in the early 1920s, and the arrival of colour in the 1930s," said Jeffrey Katzenberg, chief executive of DreamWorks Animation, which created the "Shrek" series.

"Now more than seven decades later, the movie industry is entering the third period of revolutionary change with the arrival of 3D," he said in an address to the festival on Wednesday.

Speaking to reporters later, Katzenberg said innovation and technology "have made this the magic moment" for 3D films to make a return.

3D technology enables the viewer to feel part of the movie. Objects, for example, can seem to fly directly toward them.

Film studios are banking on the new, dramatic visual experience to lure moviegoers back to cinemas, which have seen audience numbers fall with the rise of DVDs and other home entertainment formats.

While patrons still need to wear dark glasses to watch 3D films, these now come with advanced lenses and stylish designs.

Digital technology enables clear images and pristine bright colours, giving filmgoers a 3D experience without the headaches or nausea.

Katzenberg said 3D films being made now were a far cry from those in his father's era, which were viewed through "those kind of goofy red and blue cardboard" eyeglasses.

"Let's be honest, the 3D was pretty terrible. The technology was primitive, the film was blurry, people got headaches and actually some of them got nauseous," he said.

"It really wasn't much more than a cheap exploitation gimmick."

Katzenberg showed two clips of DreamWorks' forthcoming 3D animated film "Monsters vs Aliens," which got rave reviews from an audience of directors and film-makers at the festival, which ends on Sunday.

Mark Zoradi, president of Walt Disney Studios Motion Pictures Group, said his company is making "tremendous investments" in 3D films.

It has already released four of them: "Chicken Little," "Meet the Robinsons," "The Nightmare Before Christmas" and the "Hannah Montana" concert film. A fifth, "Bolt," is to hit cinemas soon.

Walt Disney says it has committed to make 17 movies in the next three years, 11 of them animated 3D films and six with live-action 3D.

Greg Foster, president of another studio giant, IMAX, said his firm also sees 3D as the future.

"3D for us internationally continues to be a very growing market," he said.

One key challenge is converting movie theatre screens worldwide to be able to show digital 3D films, the Hollywood executives said.

However, the current financial turmoil had hit the changeover.

"It takes many, many, many billions of dollars to do that and certainly that's been slowed down measurably," Katzenberg said.

In the United States, only about 1,400 out of the 30,000 movie screens have 3D capability, the executives said.

In the rest of the world, only 700 screens can show digital 3D movies.

"We have been very aggressive in trying to talk to every major exhibitor around the world about first, digital, and secondly 3D," Zoradi said.

"In the United States and in other countries we are participating in helping theatre owners convert their theatres to digital, which is the first step and most expensive part of getting 3D."

Despite the challenge of converting screens, Hollywood insists 3D is the future.

Award-winning directors Robert Zemeckis, James Cameron, Steven Spielberg, George Lucas and Peter Jackson are all involved in 3D projects, according to Katzenberg.

"They all see 3D as the next great frontier. They are the best and they attract the best... In the next few years they will be making some of the best films... all in 3D."