'Harry Potter' has 3-D on the brain

The wizardry behind the 3-D scenes in the IMAX version of Harry Potter and the Order of the Phoenix is not really magic, despite appearances. It's just a little neuroscience.

Opening today on more than 100 IMAX theater screens nationwide, this edition of the film offers the same story but in the larger IMAX format and with a leap-out-of-the-screen 3-D climax in the final 20 minutes.

"Harry Potter is about magic, Hogwarts, Quidditch. It is a big experience," says IMAX Corp. chief Greg Foster. "We look for movies about something you dream about doing."

This is the first Potter film to get the IMAX 3-D treatment, although it's just the ending that's actually 3-D. Last year's Superman Returns was the most recent Hollywood film to go IMAX with selected scenes in 3-D.

Working for weeks with the two-dimensional film, also opening today, IMAX producers have converted the conclusion to a 3-D version by using image-enhancing tricks and a great deal of computer power, says producer Lorne Orleans of IMAX Corp.

Three-dimensional film effects rely on a basic trick of neurobiology. Our eyes each have a slightly different view of the world, and it is only in the brain that the two images are welded to create depth perception. The trick to turning a two-dimensional screen image into a three-dimensional one is to simultaneously show viewers two slightly offset views of the same scene and let the brain do the rest.

"In effect, we are delivering separate right and left eye images and tricking your brain into putting them together," Orleans says. That is why 3-D movie viewers need 3-D glasses — and why you need them for this film, too — which are either polarized or electronically controlled to allow light from one view into your left eye and light from the other view into the right eye.

"Face it," Orleans says. "Take off the glasses and all you see are two overlapping pictures on a flat screen."

Scientists call this trick of depth perception "stereopsis," first described by the British researcher Charles Wheatstone in 1838. Filmmakers dabbled with the idea almost from the start, but the golden era came in the 1950s with films such as Vincent Price's classic horror flick House of Wax.

Old-fashioned matinee 3-D movies required filmmakers to shoot films with two separate camera lenses to create left-and-right view films. But for Order of the Phoenix, IMAX producers used computer algorithms to turn the original 2-D film into a 3-D version. The computers create a virtual second perspective, which serves as the film's offset lens view.

Hundreds of computers ground away for two months on the translation, Foster says, creating a virtual Harry Potter world much like the imaginary worlds created in three-dimensional computer games. (Marketers today will give away movie tickets within the online game Second Life.)

IMAX films are shot on film frames 10 times larger than conventional films, which is why they can be shown on huge screens, up to eight stories tall. The added clarity of the film, and the curved screens they are shown upon, adds to the 3-D effect, Foster says.

"We think 3-D works for blockbuster movies," he says. "It is not a panacea. Nobody wants to see My Dinner With André in 3-D."

Source : Dan Vergano, USA TODAY