Stereoscopic 3-D is not a perfect technology. Set aside the findings of experts indicating that somewhere between 2% and 12% of the population have difficulty viewing stereoscopic images. The mechanics of directing the left eye to see only the projected left-eye image, and directing the right eye to see only the projected right-eye image, has its own set of tradeoffs.
Three distinctly different classes of technology have been introduced to facilitate the stereoscopic function in cinemas: polarization, shutter-glasses, and spectral division. No one system presents the perfect solution, but clearly a winner is emerging.
Polarization, such as that from RealD and MasterImage, allows the use of very low cost glasses. The low cost makes it possible to hold an inventory, which in turn allows recycling through use of a professional washing service, or they can simply be given away to the consumer.
Shutter-glasses, such as that from Xpand, are the heaviest of the lot, battery-operated, and too expensive to give away. As it’s not economic to hold a large inventory, cinema owners usually operate their own washing service. If the wash is not anti-bacterial, it could result in the spread of eye disease, a complaint that’s been heard in Europe. Attrition and damage add to the overhead.
Spectral division glasses, such as that from Dolby, require expensive coatings on the lenses, making them expensive, although not necessarily as expensive as shutter-glasses. Still, it’s not economic for the exhibitor to hold a large inventory, resulting in in-house washing services that can suffer from the same health problems experienced with shutter-glasses. Also as with shutter-glasses, attrition and damage add to overhead.
If stopping there, one would think that shutter and spectral division glasses have no advantages. But they do: they allow the use of ordinary, “flat” projection screens. This is an advantage with those who are concerned about the projection quality of their 2-D movies. Polarization, on the other hand, requires the use of so-called “silver” screens that preserve the stereo-encoded polarization of the projected image. Silver screen technology is based on a coating comprised of microscopic aluminum flakes, each flake reflecting light without the scatter that destroys polarization encoding. But the side effect of this technology is that the angle of view will be restricted, creating a “hot” spot where the light is most efficiently reflected. Some exhibitors find this effect more acceptable with 3-D images than with 2-D images, and so may develop a preference for one of the two other technologies.
But polarization is winning. Polarized solutions now comprise 65% of the world’s cinema screens, and that number appears to be increasing. Several factors are driving this: the low cost of polarized glasses, convenience of handling, and the potential health issues imposed by other solutions.
In addition, another factor is emerging that could further shift the balance in favor of polarization: that of improved silver screens. The visible example is RealD’s introduction of its so-called “Precision White” silver screen at CinemaCon. To date, the screen is only available from MDI, and firm pricing has not been announced. MDI says the estimated cost of the Precision White screen will be 2 to 3 times the cost of the industry standard 2.4 gain silver screen. It has a gain of 1.4, and a half-gain angle of 40 degrees, quite an improvement over the typical 22 degrees found in ordinary silver screens (but not enough to make the CST in France happy, if it sticks to its specs). Of course, this screen is only available to users of RealD systems.
But the screen companies aren’t stopping there, as they have a significant stake in the success of polarized 3-D, regardless of who provides the system. Unlike flat screens, which can last a very long time, silver screens cannot be effectively cleaned, and need to be replaced every five years or so. In other words, silver screens generate a healthy refresh in sales, while flat screens don’t. To aid in the success of all 3-D polarized solutions, and not just RealD’s, the major screen companies are working on improved silver screens that don’t require a RealD license to purchase. The screens hold the promise of being significantly less expensive than the RealD screen, as well. Without completely giving away the fort, one company is pursuing a lower gain silver screen (lower than the industry standard of 2.4), while another is pursuing a higher gain silver screen, both screens having improved viewing angles.
Those exhibitors on the fence about sustaining the high expense associated with non-polarized 3-D solutions may find that the newer screens emerging later this year will be enough to tilt their decisions. Which is precisely what the screen companies want to do. Polarization is indeed set to win.
