The Challenge: Two Eyes, Two Images
The main issue with viewing 3D on a TV (or video projection screen) is that humans have two eyes, separated by a couple of inches. We see 3D in the real world because each eye sees a slightly different view of what is in front of it and transmits those views to the brain. The brain combines the two images, resulting in viewing a natural 3D image correctly. Since traditional video images displayed on a TV or projection screen are flat (2D), both eyes see the same single image. Still and motion photography tricks can provide some sense of depth and perspective within the displayed image. However, there aren’t enough spatial cues for the brain to accurately process what is being viewed as a natural 3D image.
How 3D Traditionally Works for TV Viewing
What engineers have done to solve the problem of seeing 3D from an image displayed on a TV, movie, or home video projector and screen is to send two slightly different signals that are each targeted to your left or right eye. Where 3D glasses come in is that the left and right lenses see a slightly different image. Your eyes send that information to the brain. As a result, your brain is fooled into creating the perception of a 3D image. This process isn’t perfect, as the information cues using this artificial method aren’t as detailed as the cues received in the natural world. However, if done properly, the effect can be convincing. The two parts of a 3D signal that reach your eyes require the use of either Active Shutter or Passive Polarized Glasses to see the result. When such images are viewed without 3D glasses, you see two overlapping images that look slightly out of focus.
Progress Towards Glasses-Free 3D
Although glasses-required 3D viewing is accepted for a movie theater experience, consumers have never totally accepted that requirement for viewing 3D at home. As a result, there has been a long-running quest to bring glasses-free 3D to consumers. There are several ways to execute glasses-free 3D, as outlined by Popular Science, MIT, Dolby Labs, and Stream TV Networks.
Glasses-Free 3D Products
No-glasses 3D viewing is becoming available on some smartphones, tablets, and portable game devices. To view the 3D effect, you must look at the screen from a specific viewing angle. This isn’t a big issue with small display devices. However, when scaled up to large screen TV sizes, implementing glasses-free 3D viewing is difficult and expensive. No-glasses 3D has been demonstrated in a large screen TV form factor as Toshiba, Sony, Sharp, Vizio, and LG have shown glasses-free 3D prototypes at trade shows over the years. However, glasses-free 3D TVs are marketed more to the business and institutional community. These are used mostly in digital signage display advertising. These TVs aren’t generally promoted to consumers in the U.S. However, you may be able to purchase one of the professional models offered by Stream TV Networks/IZON technologies. These models are available in the 50-inch and 65-inch screen sizes and carry high price tags. These sport 4K resolution (four times more pixels than 1080p) for 2D images and full 1080p for each eye in 3D mode. While the 3D viewing effect is narrower than viewing 2D on the same screen size set, it is wide enough for two or three people sitting on a couch to see an acceptable 3D result.
The Bottom Line
3D viewing is at an interesting crossroads. TV makers have discontinued glasses-required 3D TVs for consumers. Still, many video projectors offer 3D viewing capability as they are used in both home and professional settings. However, that still requires viewing using glasses. On the other hand, glasses-free 3D sets within the commonly available LED/LCD TV platform familiar to consumers has made great strides. Still, sets are expensive and bulky compared to the 2D counterparts. Also, the use of such sets is more confined to professional, business, and institutional applications. Research and development partnerships continue. As a result, there may be a 3D comeback if the glasses-free option becomes available and affordable. James Cameron, who sparked the modern use of 3D for entertainment viewing, is working on technology that may bring glasses-free 3D viewing to the commercial cinema. This may not be possible with current projectors and screens. However, large-scale parallax barrier and micro-LED display technologies may hold the key, so stay tuned.
