HD Advisor Forty 3-D!

Posted Fri Jan 22, 2010 at 11:40 AM PST by

Editor's Note: Each Friday, High-Def Digest's own HD Advisor will answer a new round of questions from our readers. If you have home theater questions you need answered, send an email to [email protected]

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[Please note that some updates and corrections have been made to this article since original publication as a result of reader feedback].

Answers by Joshua Zyber

3-D 101

Q: Okay go ahead and give me the bad news now. I moved into a new house last year and put a home theater into my basement with a Mitsubishi projector. I suppose when 3-D hits that I will need a new projector as well as a new Blu-ray player? My Samsung in the living room was 3-D ready when I bought it so hopefully that is fine but I hope just get 3-D in the theater I don't have to start all over again. Any thoughts?

Q: Could you please explain the technical side of 3-D-movies and distribution? I'm aware of different theater standards such as XPanD and Dolby 3D, but how come 'My Bloody Valentine' 3-D Blu-ray release is paired with only passive glasses when theaters have adopted some (i.e. previously mentioned) standard and use expensive active glasses, projector etc.? What about all these auto-stereoscopic displays? What kind of content I can watch with those? Why buy expensive displays if you could just buy some Blu-ray with free glasses and enjoy 3-D with old display?

Q: I have been trying to keep up with this rapid expansion of 3-D to home theater and I feel a bit confused, at least by the hardware aspect. I currently use a PS3 and a Samsung LCD 52inch 1080p at 60Hz. I have read that the PS3 is 3-D capable (from a hardware aspect) and will be able to play 3-D Blu-rays which is all fine and dandy. But where I get lost is in the TV. What do you need for a TV to be 3-D capable? If mine isn't (which I assume is not), why is that the case? Also, are there not a few Blu-rays already supporting 3-D? ('Coraline' comes to my mind.) And if that is a different 3-D technology than what is coming out, what is the difference? Some clarification and maybe an overall HD and 3-D 101 lesson would be much appreciated!

A: 3-D is a very complex topic. Unfortunately, I won't have enough space here to thoroughly explain all the technical workings. What I'll try to do is give a brief overview. Keep in mind that as I write this, details about the just-announced Blu-ray 3-D standard are still trickling out. Some of what I'm about to write may be based on preliminary info.

Boiled down to its simplest essence, 3-D works by presenting an image from two different angles simultaneously. Most live-action 3-D movies have been shot from the perspective of two camera lenses, either side-by-side or at a 90-degree angle using a beamsplitting rig. During playback, the movie is projected in such a way that one camera view is sent to the viewer's left eye, and the other camera view is sent to the right eye. This tricks the brain into combining the two views into a three-dimensional picture.

During the 3-D craze of the 1950s, 3-D movies were projected from two strips of film running through two projectors. Viewers in the audience wore polarized glasses that would direct the image from one projector straight to the left eye and the image from the other projector to the right eye. When it worked, this was pretty effective. Unfortunately, keeping two simultaneous projectors in sync was incredibly difficult and hard to maintain. The process was prone to breakdowns.

The brief 3-D revival of the 1980s used a single-projector process called "over and under," wherein both camera views were printed one on top of the other on a single strip of film. (A side-by-side variation may have also been used.) A special lens on the projector polarized the separate images, and viewers once again wore polarized glasses to force each view to go to the correct eye. This eliminated the mechanical problems associated with a two-projector set-up. However, it also effectively reduced the resolution of each picture by half.

Any pop culture images you may have seen with theater audiences (especially 1950s theater audiences) wearing red & blue glasses are mostly fiction. That type of 3-D has only rarely been used in theaters. The red & blue glasses are part of a process called "anaglyph" 3-D that works by tinting each original camera view a different color and then compositing them on top of one another with a slight offset. The colored lenses work as filters that only allow one of the tinted layers to each eye. Unfortunately, anyone who's ever suffered through an anaglyph presentation will tell you that it's the absolute worst form of 3-D. The glasses make the image dim and ruin all the colors. The 3-D effect is also quite poor. Robert Rodriguez's 'Spy Kids 3-D' and 'The Adventures of Sharkboy and Lava Girl' were distributed in this format, and drew almost universal scorn from viewers at the time.

Currently, there are two new forms of 3-D in use at theaters: IMAX 3-D and digital 3-D. Both are capable of presenting bright, full-color images. In IMAX 3-D, two strips of film are run through one giant projector with two lenses. Depending on the venue, viewers at IMAX theaters may wear either polarized glasses or special LCD shutter glasses that rapidly open and close, alternating between each eye in sync with the projector. The polarized glasses are cheaper and more common.

Digital 3-D comes in several different variations. Some of the brand names you might encounter are RealD, Dolby 3D Digital Cinema, or XpanD. Each is slightly different than the others, but the basic underlying principle is the same. Digital 3-D uses a single projector that alternately projects the left eye and right eye imagery in rapid succession. Viewers wear polarized or active shutter glasses again to sort out the views.

(Please note that the polarized glasses from any one of these processes may be different than the others. So you can't wear the polarized glasses from a RealD screening at an IMAX theater, or vice versa.)

So where does that leave us in the home theater hobby? Until recent technological developments, 3-D has not translated very well to home video. There have been experiments over the years with special field-sequential 3-D processes that produced a fairly effective 3-D image. But these were typically very expensive, had limited title availability, and were not compatible with progressive scan HDTVs.

For the most part, we've been stuck with crappy anaglyph 3-D on home video. It may look like garbage, but it's extremely cheap and fully compatible with any television. This is the type of 3-D you'll find on existing Blu-ray releases such as 'Coraline' and 'My Bloody Valentine'. Some discs come with the traditional red/blue glasses. Some use variations such as yellow/green or magenta/cyan. To be blunt, they all suck.

Finally, 3-D may be making a breakthrough at home. A new Blu-ray 3-D standard has just been hammered out, and countless manufacturers will be releasing 3-D HDTVs or 3-D projectors this year. Even cable and satellite providers are working on 3-D television transmissions. 2010 is poised to be the Year of 3-D.

Some of our readers may already own HDTVs that were advertised as "3-D ready." (Mitsubishi and Samsung have offered DLP models like this for a few years now.) These owners are probably wondering whether those sets will work with the new 3-D standards. The answer to that is "maybe," but probably not to its fullest potential.

High-definition 3-D once again works by presenting separate left-eye and right-eye images to the viewer. These can be delivered two ways: simultaneously or sequentially. Older 3-D HDTVs use the simultaneous method. In this, the left and right images are combined into a single 1080p frame. In some sets, the pixels alternate between the left and right views in a "checkerboard" pattern. In others, the images may be side-by-side or over/under. The downside to this is that it means the individual 1080p images are each reduced to 540p resolution. These older HDTVs may still function with the new 3-D standards with the help of a converter box (Mitsubishi has already announced one), but the picture you watch won't be true high definition.

Sequential 3-D is the superior process. Instead of cramming two 540p images into a single 1080p frame, the left and right images are each displayed at full 1080p resolution, one after the other in sequence, much like old interlaced TVs used to work. So long as the sequential images alternate fast enough, the viewer's brain will combine them into a single 3-D picture.

Different television (or projector) manufacturers may have different implementations for how to deliver those sequential images. Most will require that the viewers wear some form of 3-D glasses, primarily active shutter glasses (that can be expensive to replace if broken, or to buy extra for friends and family). A few manufacturers have developed auto-stereoscopic displays that will produce a 3-D image without glasses. How that works is incredibly complicated, and I can't begin to explain it here. The caveats to note are that auto-stereoscopic displays, 1) will be incredibly expensive at first, and 2) have extremely limited viewing angles. If you don't sit directly in the display's "sweet spot," the 3-D effect is lost.

Another key point with regard to sequential 3-D is that the images have to alternate very quickly. If they don't, this will cause a serious (perhaps even unwatchable) amount of flicker. And that's why the new 3-D formats will not work with just any HDTV. You must have a 3-D capable TV or projector. For more on that, see the response to the next question.

Are 120 Hz HDTVs Ready for 3-D?

Q: I have a Sony KDS-60A3000 and I am using a PS3 as my Blu Ray Player. Now that the Blu Ray 3-D specs have been finalized I was hoping you could tell me if I'm 3-D ready. I know that the PS3 will get a firmware update for compatibility but I'm not sure about my TV. For the last few years, I've read that as long as your TV has 120 HZ (which my TV does), I should be good to go once I buy the glasses. However, I've noticed that Sony and many other TV companies have been promoting their new TVs as "3-D Ready." Is that to say that previous models aren't? Or is that just marketing trying to get me to buy a new TV? Can I continue to enjoy my current TV (which I love, and have had professionally calibrated)? Or is it time to start saving up for a new TV? Any info you can offer to shed some light on this would be greatly appreciated.

A: Short answer: Not all 120 Hz HDTVs will work with 3-D Blu-ray. You specifically need a "3-D capable" HDTV.

Long answer: Movies (3-D or otherwise) are photographed at 24 frames per second. Up until now, most Blu-rays have been encoded at 1080p resolution, also at a 24 fps rate. Traditionally, this has been displayed at either: 1) a 60 Hz refresh rate via the addition of 3:2 Pulldown, or 2) at the original 24 fps rate or some even multiple. For more information on this, see my What's the Big Deal About 1080p24? article. Other Blu-rays (a minority, primarily concerts and documentaries) are encoded at 1080i resolution with a 60 Hz rate.

In recent years, many HDTV manufacturers have migrated toward a 120 Hz refresh rate. Some are even pushing into 240 Hz. These numbers work well because they're even multiples of both 24 and 60, and thus can easily display content of either type. However, the majority of these HDTVs will still only accept a 24 Hz or 60 Hz input signal, which the sets will then internally convert to the screens' native refresh rates. They are not designed to accept input signals at other frame rates.

The new frame-sequential high-def 3-D standard will require that both the left eye and right eye images each be displayed at the original 24 Hz or 60 Hz rate. That means that the Blu-ray player will transmit either a 48 Hz or 120 Hz output signal. Because your TV was not built to accept either of those frame rates, it cannot display the 3-D image.

Unfortunately, there is no simple solution that might entail converting the 48 Hz or 120 Hz signal to a 24 Hz or 60 Hz rate your TV will accept. Doing so will result in the frame rate for each of the left and right images being halved. On a 24 fps movie, that means that each view will be output at only 12 fps. That would cause an intolerable amount of flicker and motion stutter for any viewer.

[Update: According to this new article, 3-D Blu-ray players will not output a 1080p signal at 48 Hz or 120 Hz as I'd believed. Instead, they will output a 1920x2205 resolution signal (with two 1080p pictures stacked one above the other) at 24 Hz. It will be the responsibility of the 3-D TV or projector to convert that signal to whatever form of 3-D it ultimately displays, be that frame sequential at 120 Hz or some other format. This still remains a problem for TVs not specifically designed to accept or process that 1920x2205 signal. So my short answer remains the same: Not all 120 Hz TVs will work with 3-D.]

3-D, Receivers, and HDMI 1.4

Q: I was going to upgrade my home theatre set-up somewhat soon (next year or so), and am going to wait for a 3-D TV before I get a new TV, but was thinking of upgrading my receiver a bit sooner. I have a PS3 (original 60GB model) that I use for watching Blu-rays and DVDs. Since they recently announced that the PS3 will be capable of outputting 3-D through a firmware update, I had some questions I was hoping you could help me out with. My current understanding is that for full 1080p 3-D, you will need a HDMI 1.4 cable. Are the PS3 (and other devices) able to start using HDMI 1.4 with just a firmware update, or to fully utilize 1.4? Does HDMI 1.4 hardware have to be present? My other inquiry is in regards to a receiver. I haven't settled on a specific model yet. If I bought a receiver now, would a 3-D signal be able to be transmitted through the receiver if the receiver only supports HDMI 1.3? Would it be better to wait until receivers have 1.4?

A: I'm going to address your question in stages and work up to what I believe to be the answer. I'll be honest, this is one of those topics where the details currently available are still a little sketchy. Here's what I know:

First, HDMI 1.3 and HDMI 1.4 are different hardware specifications in the transmitter and receptor chips in your equipment. A Blu-ray player or A/V receiver with HDMI 1.3 cannot be upgraded to HDMI 1.4 with just a firmware update. You'd need the replace the hardware.

Any video or audio signal that requires a specific HDMI protocol (be it HDMI 1.3, HDMI 1.4, or even the earlier versions) will require that every piece of equipment in your signal chain meet that specification. If a 3-D Blu-ray signal requires HDMI 1.4, then your Blu-ray player, your receiver, your display, and any switchers, splitters, or video processors in between will all have to be HDMI 1.4 capable.

A possible workaround to this is to avoid sending your video signal to your A/V receiver. To accommodate this, some Blu-ray manufacturers will be offering Blu-ray players with dual HDMI outputs, one for video and one for audio. That way, you can send your video signal straight from the player to the (HDMI 1.4) TV without going through the receiver. And then you'd send your audio (which doesn't require HDMI 1.4) separately to the receiver. This is kind of a clunky stopgap solution, and necessitates extra cable clutter, but might be preferable to buying a whole new A/V receiver just for HDMI 1.4. My fear is that it might also cause HDMI handshaking problems that can be a real headache.

So, now we come to the question of whether 3-D Blu-ray will really require HDMI 1.4. From what I've gathered, the answer to that is: sort of, but not necessarily.

As I've described above, a 1080p frame-sequential 3-D image would have to be transmitted at 48 frames per second. This requires HDMI 1.4. HDMI 1.3 can't handle 1080p at that speed. [Correction. The issue is not a 48 fps rate, but rather a signal with double the pixel resolution in each frame. See update in question above.]

However, HDMI 1.3 may support 3-D Blu-ray if the picture is reduced to 1080i output resolution instead. That's how Sony plans to upgrade the PS3 to support 3-D. At least theoretically, other standalone Blu-ray players may be upgradeable as well.

This may not be as bad as some readers might assume right off the bat. At least when it comes to normal 2-D images, 1080i and 1080p output signals contain the same picture data. They're just transmitted differently. With 1080p, the entire 1920x1080 frame is transmitted all at once. With 1080i, it's split into two fields and transmitted sequentially. Any 1080p HD display will then combine the fields to reconstruct the original frames. Assuming the display has proper 2:3 Reverse Pulldown deinterlacing, there should be no noticeable reduction in picture quality.

Again, I say that this is true at least when it comes to normal 2-D images. At the present time, I'm not certain if or how 3-D will complicate this. For all of our sakes, I remain hopeful that 3-D Blu-ray will work and look just fine, even if we have to use 1080i rather than 1080p.

4k Digital Projection and 3-D

Q: In your last column, you wrote that, "all 3-D theatrical installations use 2k projectors. 4k has not made its way into the 3-D realm yet." I just wanted to point out one thing. Sony makes 4k CineAlta projectors for use in 3-D cinemas. The Alamo Drafthouse here in Austin, Texas recently moved to 3-D and digital projection and they went with the Sony 4k projectors. They're doing RealD 4k 3-D. 3-D isn't just limited to 2k anymore.

A: From my understanding, the Sony CineAlta does not actually display 3-D content at 4k resolution. A traditional 2k RealD theater will project the left eye and right eye information sequentially, much like an interlaced TV. Each eye's view is a full 2k resolution, one alternating with the other in series. However, the CineAlta projects both 2k views simultaneously to create its 3-D effect. Technically, the content still only has a resolution of 2k, even though the projector is using its full 4k panel.

Reader Rant

A couple weeks ago, we set aside the regularly scheduled Homework assignment to post some reader Hate Mail. This week, we have another new feature, the Reader Rant. The following was sent in reaction to all the industry hype about 3-D. It's a bit long (in fact, my apologies to the author, but I had to judiciously edit a good amount of the original text so that we can hone in specifically on the 3-D topic). But I think he provides a valid and interesting counter-argument worth considering.

I Hate 3-D!

Rant: I can't STAND all the buzz 'Avatar' and 3-D tech are getting! When I first heard that 'Avatar' would be in 3-D, I thought that might be a bad thing. I've seen a few movies in 3-D over the years and have always felt that not only was 3-D a gimmick, but also it didn't add anything new or special to my movie experience. Of course, here we are in 2010 and this movie has blasted off along with 3-D technology. First off, I'm the traditional kind of movie person. I love watching movies in 2-D. Well before the movie was released, I read up on the technology used for the cameras. People started to make a big deal about this movie, and then the CGI started to get a lot of buzz too. I was always skeptical, but thought that I'd still give the movie a chance when it was out. I actually started to become a little excited the few weeks before its release. Then the movie debuted and I went right after of work to see it.

I will say that the first scene of the movie with Sam Worthington in the capsule actually looked cool. I thought, though with skepticism, maybe this movie will have a lot to offer. The movie pushed forward and I watched. One thing I noticed was a problem with the bottom left and right corners of the actual screen and the way the image looked. Some of the images did not look like 3-D and instead I could actually see two different images being displayed on the screen instead of just one. That was just one minor complaint but still enough to turn me off a little.

Anyway, as the movie went on, I started to forget that the movie was in 3-D at all. The story started to become boring and I wanted out. But I watched the whole thing. Walking out of the movie, I decided that I'd wait one night and sleep on everything. The night passed and I awoke thinking about everything I had witnessed the night before. I came to the conclusion that I was very unimpressed. The 3-D technology didn't really look that much different than it has in the past. I thought that it added a small depth of field. I never felt that I was immersed in the movie and my head didn't feel that great either.

I think that the whole 3-D thing is still a big gimmick and doesn't add anything new to the format. What it does add is a bunch of extra money people have to spend to watch a movie. Of course, the movie is doing well money-wise because of the extra charge of at least 3 bucks.

Now, because of this, it really has changed the game. Companies are pushing 3-D TVs, new movies, video games and so on. The truth is that people are not going to invest into these new technologies. We as a consumer have already invested in new TVs. A lot of people will not be able to spend the extra money in something newer. Of course there will always be the next big thing, but this is just too much. 3-D is just too flawed. For instance, some people wear glasses, and putting on another pair is a bit much. There might eventually be a way around this but not now. 3-D adds extra expense for the TVs, TV provider pricing, movie pricing, and extra 3-D glasses pricing. Another flaw is that not everyone will be able to take advantage of viewing a 3-D TV because everyone will need to be wearing the 3-D glasses. It will get quite expensive to invest in all those extra 3-D glasses for family and friends.

I also think that directors pushing the 3-D tech are really just doing it because of all the money involved. They might say, "It's an artistic choice that really adds a level of dimension never seen before," but what they really mean is this is a new way to draw people into the theater to take more of our hard-earned money.

I think that Hollywood planned this push for 3-D when there was no need to. Hollywood has been making less money when comparing ticket sales but maybe, just MAYBE, if ticket prices cost less money, then maybe more people would go. But instead they hike the prices up to make it seem as though movies are breaking new records when they're really not. If we were to calculate sales for 'Avatar' minus the intake of the 3-D glasses at the average of $9, then it means 1/3 of every ticket sold is for the 3-D glasses.

IMHO, I hope that the companies invested in 3-D tech do not get upset if it does not go over well because this is one of the biggest gambles in all of tech history. My prediction is that the consumer will not buy into the tech in the long run. Only time will tell.

JZ: Honestly, I sympathize. In fact, I'm torn on the whole 3-D thing myself. As a die-hard tech nerd, I love the idea of a new toy in my home theater. But as a film lover, I've also found 3-D to be very gimmicky in most applications.

I saw 'Avatar' in 3-D and am glad that I did, for the spectacle of it, if nothing else. As a visual experience, it certainly looked cool (story issues aside). I viewed it in a RealD theater and did not experience any of the image separation problems described above. This might vary by the 3-D process used, the viewer's seating position, or issues with the specific venue itself. I recall that I did have a lot of problems with the 3-D effects in 'Coraline' early last year, at a different theater. (I was also seated way in the back that time.)

It's also possible that, due to mild astigmatism or similar vision problems, some viewers simply don't process 3-D images the same way that others do.

For what it's worth, I wear glasses and have never had a problem putting RealD or IMAX 3-D glasses on top of them.

In 'Avatar', I appreciated that Cameron focused most of his efforts on creating subtle depth effects, rather than obnoxious "Comin' at Ya!" gags. As I watched it, I was impressed by it. However, when I think back on the movie now, I don't picture it in 3-D in my mind. My memories of it consist of flat 2-D images, the same as any other movie. Frankly, I don't think the movie needed 3-D to work as a storytelling device. In a lot of respects, I do feel like 3-D is just a big gimmick, a way to lure people back to theaters and get them to buy a lot of expensive new home theater equipment.

On the other hand, don't all movies try to "draw people into the theater to take more of our hard-earned money"? Isn't that the whole point of the medium? The same complaint can be made against sound, or color, or special effects, or any other new innovation that filmmakers have ever developed.

I can't help but worry that we sound like those people who complained about the introduction of "Talkies" in the early days of cinema. "Who needs sound? It's just a gimmick! A real director can tell his story without it!" Back in 1953, the renowned French film theorist André Bazin wrote an essay arguing that CinemaScope was only useful for "spectacular" films like Westerns and biblical epics, and detrimental to other genres. He believed that widescreen composition would eliminate the use of close-ups and sophisticated editing, and reduce the psychological complexity of the art form. Needless to say, as smart of a man as Bazin was, time proved him wrong.

I believe that 3-D is a storytelling tool, like any other. Some directors will use it well and others will use it badly. The better directors will find ways to apply it artistically to many film genres, not just action and sci-fi epics. We're still in the early stages of this new 3-D revolution. Only time will tell if this is truly the start of a new era in filmmaking, or just another fad that will die out in a few years.

Check back soon for another round of answers. Keep those questions coming.

Joshua Zyber's opinions are his own and do not necessarily reflect those of this site, its owners or employees.

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