The ‘Full HD 3D Glasses Initiative’, and The State of 3D HDTV in General

I’m a big fan of modern 3D. Whenever I have the opportunity to see a movie in 3D instead of 2D, I take it. Especially IMAX 3D, which is just awesome. (I’m fortunate enough to live close to one of the best IMAX theaters in the US, and I go regularly.) Yes, 3D can be done poorly, but I find most modern 3D films handle it well. I just saw Captain America in 3D a couple of nights back and enjoyed it.

So you might expect me to have been one of the first to have jumped on the 3D HDTV bandwagon, but you’d be wrong. Oh, I fully intend to buy a 3D HDTV, but I’m waiting for the industry to shake out a bit. I’ll let them work out the kinks, mature the technology, and get prices down a bit more, then I’ll upgrade.

One of those ‘kinks’ that I’ve been waiting for them to work out is the idiocy of having multiple, incompatible systems for the glasses. Most vendors today use active shutter glasses, but the glasses from one vendor won’t work with a TV from another vendor, which means your friends with a Sony TV can’t bring their glasses over for movie night on your Samsung. OK, let me step back and give a quick overview of where we stand. Oversimplified, but it’ll suffice.

We see the world in 3D because each eye sees objects from a slightly different angle. The brain uses this parallax to calculate the distances and provide depth to what we see. But projected images, like conventional TV, all come from the same plane – they’re 2D. There is no parallax, and thus no depth. So the obvious solution is to provide a different image to each eye, each simulating a different angle, creating the illusion of parallax to provide depth. But that’s simpler to explain than to do.

Older 3D systems tended to be anaglyph, using different color filters for each eye – often red & blue, but there are a number of systems. The two images would be projected with matching color filters, and the filters in the glasses meant each eye only perceived the corresponding color projected. This system works well enough for B&W, but the nature of the system – colored filters – often wrecks havoc with the colors in a color image. And it isn’t that sharp, you get bleed through from the opposite eye’s image if the filters don’t block 100%, etc. Anaglyph is still used for printed materials, and sometimes for video, but it is really used mainly as a novelty these days.

Modern theatrical systems are almost all based on polarized light. The glasses are similar to quality polarized sunglasses, only allowing light waves moving in one direction to pass through. A simple way to imagine it is that you can give light a left hand twist or a right hand twist as you project it. So the 3D system does both – using left hand for the left eye and right hand for the right eye. Corresponding filters in the glasses allow only the matching twist through, so that eye sees only the image projected for it. These systems work fairly well, the only real drawback is that the glasses block some of the light, and so make things dimmer – but that’s easily compensated for by increasing the brightness of the image. Since the glasses are simple lenses and all of the work is done in the projector – or the TV – these systems are called ‘passive’. The advantage is that the glasses are simple, cheap, and light. They aren’t quite universally compatible, as there are different ways to do the polarization (mainly circular polarization vs. linear polarization), but most theaters, and passive 3D HDTVs, use the same system so de facto they tend to be.

On the other hand, most 3D HDTVs today use active shutter glasses instead. As the name implies, in this system the glasses are an active part of the system. Instead of each eye receiving a constant stream of light, filtered for that eye, active shutter systems alternate images to each eye. The glasses contain liquid crystal lenses (similar to the LCDs in a digital watch) which alternate between transparent and opaque – exactly out of phase. So the left eye receives the image while the right eye is blocked, and vice versa. This is sync’d with the image on the screen, so a left eye image is shown while the left lens is transparent, etc. The downside to this is that the glasses are complex, relatively heavy, expensive, and need to be recharged regularly. Oh, and each vendor has used a different synchronization system, making them incompatible, as above, but I’ll get back to that.

So, why do only a few vendors (like LG & Vizio) use passive 3D while the rest use active 3D with the expensive glasses? Well, active 3D is a higher quality solution for the home right now. See, with active 3D each eye sees the full image. So if you have a 1920x1080p ‘Full HD’ display, then each eye gets Full HD – just half the time. But with the displays refreshing at 120Hz or 240Hz, you still get the effect of full HD since the brain can’t tell the difference. It is still equivalent to 60Hz or 120Hz per eye. (Remember classic film is 24 frames per second and, in the US, classic TV was only 30fps (OK, 29.97).) On the other hand, passive 3D systems today use fixed polarizing filters on top of the screen which divide the image in half, line by line. So every even line is for one eye and every odd line is for the other. The end result is that each eye is only getting half resolution, so your 1080p set is only 540p in 3D mode. This is another one of those kinks I mentioned, and it will be resolved, which I’ll get to – but first, back to active shutters.

So, active shutter glasses are more expensive and complex, but provide a better image. That’s fine. But they’re expensive, with prices ranging from $50 to $200, while passive glasses start at a couple of bucks. The cost of active glasses wouldn’t be so bad, except for the compatibility problem and the stinginess of vendors. When you buy your shiny new 3D HDTV it may not even come with a pair of glasses. And when they do, it is generally just one or two pair. If you have a family with more people, or ever want to have friends over for a movie night, you need more glasses. Maybe your friends have their own 3D HDTV – great, they can bring their glasses. What, they have a different brand of TV? Oh, that’s too bad.

Different vendors have used different systems to keep the glasses in sync. There are IR- and RF-based systems, using different protocols. So while Sony, Samsung, and Panasonic, for example, all have used IR – they’ve used different IR protocols. Some vendors, like XPAND, have seen this as an opportunity and have been producing ‘universal’ glasses which implement multiple standards to work with multiple TVs, but it still means buying more if your TV came with vendor-specific glasses. Finally the main vendors supporting active shutter, Sony, Samsung, Panasonic, and XPAND, have formed the ‘Full HD 3D Glasses Initiative‘ to produce universally compatible glasses across all members.

The new glasses will support RF and IR protocols. Of course, they’re not expected to be available until 2012, but they will be backwards compatible with 2011 model 3D HDTVs. Basically they’re going to cram all of the protocols into one set of glasses for backwards compatibility, though it sounds like going forward the vendors will be using Bluetooth as a standard RF system on their sets. So one day we may have one protocol across all of the sets, which would allow for simpler ‘universal’ glasses.

So that’s one kink worked out, or at least on the path there. So, time for me to start shopping for that 3D TV.

Actually, no. See, I don’t like active 3D. Sure, the image is great and all, but I don’t like the heavy, or at least heavier, glasses and the costs involved. I have a hard enough time remembering to plug in my PS3 controllers to keep them charged, I don’t want to deal with having to keep my 3D glasses charged. Or worry about them falling into the couch or getting sat on, etc. I think the RealD glasses at the theater are pretty comfortable, and you can even buy custom, designer, even prescription, passive 3D glasses if you want. I’m a big fan of passive 3D, in other words. But I’m not willing to sacrifice quality either, the kink I mentioned earlier.

Fortunately, that’s on its way to being resolved too. While current passive 3D systems use a passive, fixed polarizing screen on a conventional HD display, that’s not the only way to do it. One obvious solution – up the native resolution of the display. If you’re halving the resolution for each eye, the higher the native resolution of the display, the higher the resolution for each eye. A 4k native display would provide better than Full HD for each eye. But making such high resolution displays in large panel sizes is a very expensive option today.

There’s another approach though, as pursued by RealD in their RDZ system, add an active polarizer to the screen. This is kind of a hybrid between active shutter and passive 3D systems. The glasses are passive, but an active layer is added to the screen. Instead of an on/off shutter, it is a polarizer, that alternatively polarizes the full image left or right. While the glasses are passive, since each lens only allows the matching image through, one eye sees nothing while the other sees the image, just like with active 3D. But all of the complexity and cost is in the TV. The glasses are literally the same as used in the theater – if you need more just bring them home next time you go, instead of tossing them in the recycling bin.

Sets using RDZ are expected to hit the market in 2012 from Samsung, and there will probably be similar, competing systems. Personally I think this solution is the best of both worlds. You get the Full HD image quality with cheap, lightweight glasses. Cheap enough that you can have plenty on hand for friends, and not worry about breaking or losing a pair. And if you need prescription lenses (as my fiancée wears) you can have prescription 3D glasses made that you can use at home and in the theater. No more having to sacrifice clarity for 3D, or trying to wear two pairs of glasses. It is hard to justify the cost of a prescription pair just for the theater, even for a die-hard movie goer, but if you can use the same glasses at home all the time, it is easier to justify.

Oh, yeah, I left out ‘glasses free’ 3D systems. That wasn’t an accident; I’m extremely unimpressed with them. They work OK on small displays – cell phones, handhelds, etc. – though even there they have major limitations. But they have too many drawbacks. Glasses free systems work via two major systems – lenticular screens or filter slats. Lenticular screens are familiar to most people – you know those images that seem to move when you tip them back and forth? Those have a lenticular screen on top. Basically rows of linear lenses that create ‘slices’ of an image. so when you view at a given angle you seen only specific slices, as directed by the lens. If you ever see one of the images without the lens in place it looks like several images all sliced up into ribbons, interlaced with each other. And that’s exactly what the display is doing – it is actually displaying columns of left & right images interlaced, and using the lens to direct each one to one eye. The slat system works in a similar manner, but even simpler. There are vertical slats positioned in front of the display designed to simply block every other column of pixels from each eye. But in such a way that it blocks the odd columns for one eye, and the even columns for the other.

So, in these systems you have the same drawback as today’s passive 3D – it halves the resolution. But, worse, there are very specific fixed points (or point in some cases) for viewing. While active and passive glasses systems work pretty much from any viewing angle the display supports, with glasses free systems you have to be in one of the ‘sweet spots’ where the effect works. Anywhere else and you may see nothing, or garbage, or 2D, it depends. Again, you know those cheap lenticular pictures? Know how as you tip them, as one image dissolves into the next there is a point where it is neither image and just a mess? The displays are like that, if you sit in the wrong place.

I’ll never say never, but to date I haven’t seen anything out or announced that truly resolves these issues with glasses free 3D. I’ve seen systems that will increase the number of viable points for viewing, but that’s just polishing a turd. You still have finite points and you still lose quality. Until someone comes up with a real breakthrough I think passive Full HD 3D will be the best option. I’m just waiting for it to arrive – and be priced reasonably, of course. I picked up my current set, a 61″ Samsung 1080p DLP, in late 2006, so it has plenty of life left in it. I can wait.

Press release spotted via Engadget.