When the 3D version of The Hobbit: An Unexpected Journey debuts in movie theaters on December 14, the film will likely wow viewers with its special effects.
But audiences at select theaters will get even more bang for their buck: they’ll be the first to witness a new technology that displays images at a rate of 48 frames per second, twice as fast as the current standard.
The new display rate is sure to look different. Whether audiences will like it is less certain. So far, early reviews have been mixed, according to 3D Focus, a website that tracks changes in 3D-viewing technology.
Some people think the effects look "too real." For others, eyestrain, headaches, nausea and other discomforts are as much of a hazard as they were with the older technologies.
That's because most films that are designed to make images look like they are popping out of the screen work by showing each eye different pictures at different times. That forces the brain to merge conflicting messages -- an obstacle that 3D studios are still working to overcome.
"People really differ," said Marty Banks, a vision scientist at the University of California, Berkeley. "Some people just don't get it and they're fine. Other people are fairly uncomfortable. The industry is really worried about this. They're listening to us scientists and they’re taking our advice."
All movies, whether "2D" or "3D" create the illusion of movement by flashing one still image after another onto the screen at a rate that is fast enough to fool our brains into seeing action. If the sequence of images is presented too slowly, the result is a shaky effect called "judder" that can sometimes look like a double image.
3D technology (which Banks prefers to call stereo-3D or S3D because even "2D" movies look three-dimensional) raises the risk for judder because these films usually show screen shots in an alternating sequence to one eye at a time. First the left eye sees an image, then the right eye sees one, then the left eye sees the next image, and so on.
With the latest generation of 3D glasses, polarizing filters allow each eye to see light coming from just one direction, and screen shots are displayed so that a single lens is targeted at a time. When one eye is stimulated, the other eye is presented with darkness.
It's up to the brain to put everything together into a coherent picture. But with each eye seeing alternating flashes of brightness and darkness, jumpy judder can creep in, causing distraction or discomfort.
To solve that problem, 3D films that are shot at a standard 24 frames per second actually show each eye in sequence three times in a row with flashes of darkness in between. That pattern continues for the entire film. This "triple flashing" allows each eye to see 72 flashes per second, which reduces flicker effects.
For the new Hobbit, director Peter Jackson used new technology to film at 48 frames per second instead of 24. In real life, our visual systems take in information continuously, and some experts speculate that images will need to be captured at more than 100 or even 150 frames per second before a movie looks truly real. But with any increase in frame-rate speed, motion should look smoother and more realistic.
"As you increase the rate of new incoming data, you're getting closer and closer to the real world," Banks said. "At some rate, you will get to the point where you can’t tell the difference."
But first, moviemakers have some technical issues to deal with.
One question, Engle said, is whether the technological limitations of the projectors used by most theaters will require them to use fewer flashes for each eye before switching to the other eye’s image -- a switch that could actually cause new stuttering problems.
Some theaters use a dual-projector set-up that gets around that issue by showing images to both eyes at the same time, and in those cases, Engle said, the results should be spectacular. But theaters that use a single projector to display 3D movies will have some new decisions to make, and audiences might not be universally happy about the final product.
"You have to be careful what you wish for," said Rob Engle, 3D supervisor at a major film studio in Los Angeles, Calif. "If you have to make compromises in order to increase the frame rate by decreasing the flash rate, you start to run into trade-offs."
As higher frame rates lead to more realism, dismay is also cropping up among people who are used to seeing films that look like films rather than television or real life. Similar complaints have emerged whenever filmmaking technology has risen to a new level over the decades.
"Every time we've moved closer to reality by adding sound, adding color or getting rid of scratches, in the end, the audience has accepted it and there's no going back," Banks said. "I think the same is going to be true here.
"In the end, we all want immersion. We want to feel like we're in that scene and closer to reality. I think once people see it, they are going to go, 'Wow. I want that.'"