3D Television FAQ
The recent flood of news about new 3D TVs, itself spurred by the hype surrounding the 3D release of "Avatar," has raised a few questions. This article, arranged in the tried-but-true manner of "Frequently Asked Questions," attempts to answer them.
When this FAQ was first published in 2010 we polled the major TV makers that announced new 3D models - LG, Panasonic, Samsung, etc - to help with some answers. We also gleaned information from enthusiast sites like AVS forum and EngadgetHD.
1. What is 3D TV?
3D TV is a generic term for a display technology that lets home viewers experience TV programs, movies, games, and other video content in a stereoscopic effect. It adds the illusion of a third dimension, depth, to current TV and HDTV display technology, which is typically limited to only height and width ("2D").
2. How can you get 3D from a 2D screen?
A 3D TV or theater screen showing 3D content displays two separate images of the same scene simultaneously, one intended for the viewer's right eye and one for the left eye. The two full-size images occupy the entire screen and appear intermixed with one another - objects in one image are often repeated or skewed slightly to the left (or right) of corresponding objects in the other - when viewed without the aid of special 3D glasses. When viewers don the glasses, they can perceive these two images as a single 3D image.
Here's what a 3D video game looks like without the glasses.
The system relies on a visual process called stereopsis. The eyes of an adult human lie about 2.5 inches apart, which lets each eye see objects from slightly different angles. The two images on a 3D TV screen present objects from two slightly different angles as well, and when those images combine in the viewer's mind with the aid of the glasses, the illusion of depth is created.
3. How is the new 3D TV technology different from older 3D?
Most people are familiar with the old anaglyph method, where a pair of glasses with lenses tinted red and cyan (or other colors) is used to combine two false-color images. The result seen by the viewer is discolored and usually lower-resolution than the new method.
The principal improvements afforded by new 3D TV technologies are full color and high resolution - reportedly full 1080p HD resolution for both eyes in the Blu-ray 3D, for example, and half that resolution in the DirecTV system. We expect DirecTV's 3D channels to look quite sharp despite lack of full 1080p resolution; see HDTV resolution explained for some reasons why.
A pair of LC shutter glasses
New 3D TVs require active liquid crystal shutter glasses, which work by very quickly blocking each eye in sequence (120 times per second systems like Panasonic's Full HD 3D). The glasses, in addition to the liquid-crystal lenses, contain electronics and batteries (typically good for 80 or more hours), that sync to the TV via an infrared or Bluetooth signal.
(Note: For the remainder of this article, any mention of "3D" refers to the new full-color, high-resolution version, not the old anaglyph variety.)
4. How is 3D TV different from 3D in the theater?
Many viewers have experienced newer 3D presentations, such as IMAX 3D, in movie theaters. Though the technologies differ somewhat - most theaters use passive polarized 3D glasses, for example - the main practical difference between 3D TV in the home and theatrical 3D is the size of the screen. In the home, the image is generally much smaller, occupying a lower percentage of viewers' fields of vision. Among TV makers we asked, some recommend a closer seating distance (of 3x the screen height away - about 6.2 feet from a 50-inch screen) for a better experience. We suspect sitting closer or watching on a bigger screen will definitely help with any home 3D presentation. Smaller screens may also present other issues unique to 3D, such as a relatively narrow viewing distance range.
One advantage of 3D TV at home as opposed to the theater is user control. You can generally sit where you want relative to the screen at home, and some 3D compatible TVs provide some control over the 3D experience in addition to standard picture settings. For example, some sets allow you to adjust the "G axis," or the amount of 3D effect, to taste, comfort or to compensate for variations in eye spacing.
5. Can everyone see 3D?
No. Between 5 percent and 10 percent of Americans suffer from stereo blindness, according to the College of Optometrists in Vision Development. They often have good depth perception - which relies on more than just stereopsis - but cannot perceive the depth dimension of 3D video presentations. Some stereo-blind viewers can watch 3D material with no problem as long as they wear glasses; it simply appears as 2D to them. Others may experience headaches, eye fatigue or other problems.
6. I've heard 3D causes headaches. Is that true?
Most people watching 3D suffer no ill effects after a brief orientation period lasting a few seconds as the image "snaps" into place, but in others, 3D can cause disorientation or headaches after extended periods. Viewer comfort is a major concern of 3D content producers; too much of a 3D effect can become tiresome after a while, abrupt camera movement can be disorienting, and certain onscreen objects can appear blurry, for example. Creators of 3D movies for children also have to account for the fact that a child's eyes are closer together (about 2 inches) than an adult's.
7. Does everyone watching a 3D TV need to wear the glasses?
Yes. Every member of a family sitting around the 3D TV, for example, must wear the glasses to see the 3D effect. If they don't, the image on the screen will appear doubled, distorted, and, for most practical purposes, unwatchable. Currently, there's no technology that lets a single TV display both 2D and 3D content simultaneously without glasses.
People who wear normal prescription lenses already can experience the full effect - and generally suffer little or no discomfort - by wearing the 3D glasses too, which are designed to fit over an existing pair of glasses.
8. Do I need a new TV?
Yes. With one exception, none of the TV manufacturers we spoke with said that any of their current HDTV's can be upgraded to support the new 3D formats used by Blu-ray, DirecTV and others. One reason we've been given is that the TV must be able to accept a higher-bandwidth signal (technically 120Hz) to display Blu-ray 3D, and older TVs can typically only accept relatively lower-bandwidth (60Hz or less) signals. That's potentially confusing because many non-3D LCD's have 120Hz and 240Hz refresh rates, and manufacturer marketing also mentions "600Hz" plasmas. Regardless of the "Hz" spec, these non-3D models can only handle a source that outputs at 60Hz or less via HDMI - the "conversion" to a higher rate, if applicable, occurs inside the TV itself.
Another reason is that 3D requires different video processing and additional hardware, including some way to send the necessary Infrared or Bluetooth signal to the 3D glasses. We're not ruling out the possibility of third-party add-ons overcoming these limitations, but as of now there's no way to convert any 2D TV to be compatible with the new 3D TV formats.
The exception applies to the approximately 4 million 3D compatible rear-projection DLP’s sold in the last few years by Mitsubishi. All of them require a special 3D kit to display 3D. Mitsubishi has a converter box (model 3DC-1000) that will allow those older TV’s to display 3D Blu-ray, DirecTV and other new 3D formats.
9. Do I need a new Blu-ray player, cable box, game console, or AV receiver?
With one huge exception the answer for Blu-ray players is "yes." A new 3D Blu-ray player will be required for many viewers to view the new 3D Blu-rays.
The Sony PS3 is the huge exception. Sony says that the game console will receive two separate firmware upgrades - one for gaming and another to allow display of 3D Blu-rays - in June 2010. Previously there was some confusion about whether the Blu-ray capability of the console would in fact be full HD resolution as seen on newer standalone Blu-ray players, but Sony says that it will, despite the fact that the PS3 is not HDMI 1.4-certified (question 10). When we asked about another rumor, which hinted that the console's 3D capability would only work with Sony TVs, the company replied that the PS3 would work in 3D with any 3D-compatible TV, regardless of brand.
As for the Xbox 360 and the Wii, neither Microsoft nor Nintendo has outlined its plans for 3D gaming.
DirecTV has said that its lower-resolution 3D system will require only a free software update to the company's current HD boxes. No other TV provider has announced 3D yet, but we assume some will follow suit and enable 3D without a new box.
Unless you use your AV receiver for switching between HDMI video sources, you won't have to upgrade to enjoy 3D Blu-ray movies. If you do want to retain HDMI switching on a receiver with even a single 3D source (with the possible exception of the PS3), you will need to get an AV receiver that's 3D compatible. Numerous AV receiver makers have announced 3D-ready 2010 models.
10. Can I use my existing HDMI cables?
At this point, it appears you can. We've heard conflicting reports from manufacturers, but the best information we have indicates that most current HDMI cables will work fine with the new 3D formats. One caveat is that the longer cables, say over 12 feet, might have problems. We recommend trying to use your old cables before spending extra on "high-speed," "HDMI 1.4-certified" or "3D-ready" HDMI cables.
11. Can I watch current 2D shows, movies, games, and other content in 3D?
That depends on the TV. LG, Samsung, and others include 2D to 3D conversion processing on some models that allows viewers to "watch everything in 3D." This feature works best with HD and BluRay programming but is also quite effect with standard DVD’s. However, with low resolution sources like VHS or Analog TV, we recommend staying with 2D.
12. Can the 3D feature on a 3D TV be turned off?
Yes. All 3D TVs will display current 2D content with no problem and no glasses required, and the picture quality in 2D won’t be any worse than on an equivalent 2D HDTV. The Blu-ray 3D specification calls for all such discs to also include a 2D version of the movie, allowing current 2D players to play them with no problem.
13. Do 3D TVs use more power?
On their own, the answer is no. There is no difference in stated power consumption between 2D and 3D Televisions.
On the other hand, it's true that the active LC shutter glasses effectively block half of the light arriving from the screen, and the lenses are not entirely transparent to begin with, so logically a TV displaying a 3D image could use more power than the same TV to produce a 2D image of equivalent brightness if one increases the light output (a major component of power use) to make up for the dimmer image when viewed through the glasses.
14. Are 3D TV glasses interchangeable between brands?
Glasses are currently proprietary for each manufacturer, so for example if you have a Samsung 3D TV, only the Samsung 3D glasses will work with it. In some rare cases manufacturers may be sourcing the same glasses from the same supplier. However, play it safe and only purchase glasses that are approved for use with your brand of TV.
15. Will 3D TVs work with all 3D formats?
Unlike with Blu-ray versus HD DVD, there doesn't seem to be a major "format war" between the various methods for delivering 3D. All of the TV makers so far have specified that their 3D sets would work with the Blu-ray format, and we expect them all to support DirecTV's 3D channels and the well-established RealD format as well. In short, compatibility shouldn't be a major hurdle for 3D TVs, although the glasses are proprietary to each manufacturer (question 14).
(This article was adapted from a CNET article written by David Katzmaier.)