Jan 29 Podcast #410: The Details Behind 3D TV
Far be it from us to stay away from the latest juicy new idea in home theater technology, 3D. It's been all over the news and the blogs for a while, recently culminating with a huge display at CES. Whether or not the technology actually catches on is a discussion for a different day. Today we're going to talk about the technology behind it.
Listen to the show
Today's Show:
News:
- Gadgets techies can live without
- OPPO Releases New BDP-80 Blu-ray Disc Player
- LED to Surpass CCFL in Large-Area TFT LCD Backlights in 2011
- SRS Labs Touts TruVolume Traction
Other:
Mac Expo
Your Mac Should be on TV - Apple Home Theater Demystified
Feb. 12, 2010 3:45 PM - 4:15 PM
Speaker(s): Adam Christianson, Podcaster, The Maccast, Ara Derderian, Podcaster, HDTV Podcast
The Details Behind 3D TV
Far be it from us to stay away from the latest juicy new idea in home theater technology, 3D. It's been all over the news and the blogs for a while, recently culminating with a huge display at CES. Whether or not the technology actually catches on is a discussion for a different day. Today we're going to talk about the technology behind it.
The human eye is an amazing thing. Put two of them working together and things really come into focus (pardon the pun). The truth is that your brain uses the fact that each eye sees the world from a slightly different angle to create depth perception. This whole "two images at once from slightly different angles" concept is the basis behind 3D technology.
There are many different approaches to 3D. We'll do our best to cover the big 4.
Anaglyphic 3D
Everyone remembers stopping by 7-11 to pick up your red and blue cardboard glasses so you could watch Elvira Mistress of the Dark in 3D. Be honest, you watched it. In the red and blue system, two images are displayed on the screen simultaneously, one in red and the other in blue.
The glasses filter the image so that each eye only sees one of them. Your brain fills in the gaps and creates a 3D image. Viola, Elvira in your living room! This method sacrifices allot of quality in the image because it's actually using color to create the separation. But the benefit is that any color display can use it to create a 3D experience.
More information on Anaglyphic 3D
Polarized 3D
This is the technology that has become all the rage. Every demo we saw at CES from the major manufactures was a polarized 3D implementation. It comes in two main flavors, active glasses and passive glasses.
Passive Polarized 3D
If you've seen a movie in RealD, sometimes simply marketed as Digital 3D, you've seen a Passive Polarized 3D movie. In these glasses, the lenses have a reverse polarization, one clockwise and the other counter-clockwise. Alternating frames of the movie also alternate polarization, so that each frame is only seen by one eye. The frames change so quickly your brain can convert them into a 3D image.
This method provides really cheap glasses, but in addition to a new 3D capable projector, it also requires a special screen. The screen must be able to preserve the polarization of the light source. For home viewing on a flat panel, this shouldn't be an issue. But if you want to build your own 3D front projection theater, you'll need to keep it in mind.
More info on Polarized 3D (RealD 3D)
Active Polarized 3D
Dolby 3D, and most of the demos we saw at CES, use an active polarized 3D technology. In this version, the glasses do all the work. They work like shutters, opening and closing alternating lenses in sync with the refresh rate of the screen. Of course this requires the screen refresh at least twice as fast as normal (120 Hz) so that each eye gets the full progressive video (60 fps).
The glasses are based on LCD technology and open and close when voltage is applied just like the pixels on an LCD TV. They require power (batteries) and must run in perfect sync with the display. That's what makes them so darn expensive. And what will probably make them difficult to interchange should you and a friend have 3D TVs from different manufacturers.
More info on Active shutter glasses
Lenticular 3D
This is the technology that many think will need to be perfected before 3D TV will really take off. It doesn't require any glasses. Instead, the TV itself incorporates a special lens that can send different information to each eye. The obvious problem with current implementations is that you have to be in just the right spot, the sweet spot, to see the 3D effect. Wander anywhere off angle and the 3D either disappears or the screen gets really blurry and distorted.
We've seen many demos of Lenticular 3D, none of them at all ready for prime time.
Reader Comments (7)
In the active system, is polarization even involved? if so, how?
I though the diplay just alternated the left and right images with the glasses blocking the correct eye in sync.
Brian
(Responding to article, haven't listened to show yet.)
Uh, guys, Dolby 3D is neither active nor polarized. It uses two sets of RGB colors at slightly different frequencies. The (passive) glasses have filters which allow only one set of RGB to the left eye, and the other set to the right eye. These filters are more expensive than the polarized kind, so the glasses can't be throw-away and are built to be reusable.
While I think it would be difficult to adapt this technology to flat panel displays, it should be relatively simple to implement it in front projectors (or rear, for that matter).
Also RealD is only passive in it's theater incarnation, their TV variant is active polarized like all the others. The article is a little muddled in this respect.
Brian:
Polarization isn't technically required for shutter-glass-type systems. However, since all current shutter glasses use LCD, it is involved. (LCD doesn't really block/not-block light, it actually rotates, or not, the polarization of the light which is turned into blocking with the addition of a passive polarizer.)
What Plasma?
I have a 42inch 720P Samsung plasma display but have sold my house and the TV is staying here mounted on the wall.
I have been looking for a new 50 inch display and was either going to by a Panasonic or Samsung plasma 1080P however a friend works in a big box store and can get me a good deal on a LG about $400 cheaper than the Samsung or Panasonic.
Is the LG any good its hard to tell in the shop with the high ceiling and fluro lights, if anyone has any comments that would be useful it we connected up to a Samsung BDP 1600 and Onkyo 706 amp.
I have question for Ara or anyone who may know for that matter, on the latest show Ara said " I don't think 3D works in the home, unless you've got a HUGE TV" Which is something that I agree with that's why 3d movies look really good on theaters.
I have a 72" Samsung DLP (HL72A650) And I was wondering if that's big enough to really appreciate 3D content, if not what do you guys consider big enough.
Thank you.
George
Hi George,
Think iMax. If that 72 inches fills up the wall in front of you and you are sitting pretty close it should work fairly well. But I'm thinking a front projector in a darken room is what it will take to really enjoy this technology.
Ara
Good point George,
Specific to Ara's point, I have a 130" screen using an hd projector in my basement. I think the experience with 3D might work well with that size. But with my 50" plasma upstairs I don't think 3D would be of much benefit at all.
I have a Mitsu 73" 837 DLP TV that is 3D ready. I can purchase the emitter and glasses which are of the shutter type. I was wondering if these work with movies that are released on blu-ray in 3D that come with the cheap cardboard red/blue glasses..like the new Final Destination movie..