Dolby, known for their ubiquitous sound system, is making a bid to challenge RealD in the multiplex for your 3D viewing experience. If you've seen a 3D film recently — Monsters vs. Aliens, Coraline, My Bloody Valentine 3D — you've already experienced the RealD system.
RealD is based on polarized projection of the film that requires a special silver screen. When you take off your glasses at a RealD screening what you see is double image — the right eye and the left eye images projected on the screen at the same time.
In the early history of film all theater screens has a 'silver' coating. This was to help compensate for the dimmer projectors of the time; the silver screen was brighter than a white one. The reason for using a silver screen with 3D projection is that the polarized light striking it will remain polarized as it is reflected back.
This silver screen, along with the digital projectors, is the most expensive part of the installation. Inexpensive polarized glasses — previously with cardboard frames, now molded plastic ones are standard — are distributed to the audience at each showing.
Dolby's new system also uses polarized projection but does not require installation of a silver screen, a major savings for the theater chains. It does, however, use a special multi-coated lens for viewing and these 3D glasses are not cheap. They cost about $25 a pair to produce.
For this to be practical tight control over the distribution and collection of these Dolby glasses is obviously needed.
Here are the Dolby advantages, taken from their web site:
• Delivers realistic color and a sharper, clearer image from every seat in the house
• Extends the capabilities of Dolby Digital Cinema’s established, proven technology
• Ensures compatibility with your existing equipment by using a simple digital
projector filter accessory, easily switching between 2D and 3D
• Maximizes flexibility by using a standard white screen rather than a costly silver screen
• Reduces costs with a one-time investment and no annual licensing fee
If you went to an Imax theater in the 1980s you may recall that you had to wear a helmet-type set of goggles with LCD screens for lenses. These lenses were controlled by a radio signal and alternately went rapidly from opaque to clear, delivering to each eye the correct Left or Right image. This blinking sequence had to be matched precisely to the images being projected.
While the technology behind this was brand-spanking new in the 80s, the concept had been successfully demonstrated back in December 1922 in New York City at the Selwyn Theater using a mechanical system called Teleview.
Two projectors were used along with viewers attached to the seats all of which were synchronized. Alternate frames of left and right eye images are projected and due to the persistence of vision a moving 3D image was perceived by the viewer. The only feature produced using this system was The Man From M.A.R.S. (later re-released as Radio-Mania).
For a fascinating, detailed discussion about the Teleview system please go to Dan Symmes site, here.