3D TVs Are Confusing

This blog is mostly meant to be an opinion blog. This post will probably be a little different. I'm going to get into my opinion on things a bit later, but to start off I need to just explain the technical details of how 3D TV works, because to understand my opinion on them, you need to first understand how unnecessarily complicated 3D TV buying is.
3D is usually done in one of 4 different ways on TV: anaglyph, active shutter, passive, or auto-stereoscopic.

• Anaglyph. For starters, I'll be talking about anaglyph, since it's the cheapest and most familiar form of 3D that people are aware of. Heck, this blog's name is a reference to the anaglyph method of creating 3D images, and my blog's background (at the time of writing this post) is an anaglyph image. Anaglyph takes an image, and filters its colors so that you can use colored lenses to separate the images and send one to each eye. The way it works is that the colored lenses filter out all the light of a specific color set (usually red for one eye, and the combined blue-green color, "cyan," for the other eye), making it so that only one color goes to one eye, and all the other colors go to the other. The advantages of this method are that it is dirt cheap. You can buy red/cyan glasses on Amazon for around $3, and even that's ridiculously overpriced since many 3D DVDs will give away colored 3D glasses with the movie for free (e.g. Coraline, Ice Age 4, Journey to the Center of the Earth). Aside from being utterly expendable, anaglyph 3D also allows full resolution images to be sent to each eye. Anaglyph images are also the most mobile, as they don't require a special TV to use, or for that matter a TV at all (Anaglyph is the only form of stereoscopic 3D that works on printed paper, for reasons I'll get into later). The disadvantages are that this format stresses your eyes in ways other formats don't, since it's sending conflicting images (due to the different colors) to each eye. Also, because it's filtering colors, it makes the final image appear to be colored differently. It also means that the effect can be ruined and cause excessive ghosting (seeing double images) if the color on your monitor/TV are a little off. Wherever possible, people today avoid using this type of 3D imagery for TVs.

• Active Shutter Active Shutter TVs were the first 3D TVs to start appearing on the market. The exact date depends on what you want to say qualifies, but these became something regular people could buy without specifically looking for them around 2009, in response to the popularity of Avatar. The TVs themselves are different than regular TVs because, rather than the standard 60 Hz refresh rate that regular TVs have, which means they max out at being able to display 60 images per second, 3D TVs have a refresh rate of at least 120 Hz, which means they can display 120 images per second. Active Shutter 3D TVs get their name from the type of glasses they use. These glasses have liquid crystal displays that switch between dark and light, making it so only one eye is actually looking through the glasses at any given time. It then displays images on the screen with every other frame going to your right eye, and the other frames going to the left eye. The net effect is that this gives you a full resolution, full color 3D image, but with a slight flicker (lasting for 1/120th of a second and occurring 60 times each second). The advantage is that this gives the clearest 3D picture out of all of the 3D technologies available, since it offers a full resolution picture and doesn't filter color or light. It's also advantageous to 2D gamers, because that higher framerate gives you a competitive visual advantage (as well as a clearer picture). The biggest disadvantage is that flicker, which is both distracting and can induce headaches. It also increases the risk of a photosensitive reaction, so you'll want to use Active Shutter TVs with caution if you're prone to seizures. Another big disadvantage is that these TVs are expensive due to the higher framerate, and the glasses are expensive due to the liquid crystals and electronics needed to sync it with the TV.

• Passive Lens Passive 3D TVs are TVs that use the same kinds of glasses as the ones you receive in a RealD 3D showing of a movie (and work on most passive 3D TVs if you take those glasses home with you). The way this works is that half of the pixels (single dots on the TV screen) are polarizing light one way, and the other half are polarizing it another way. That's a very complicated procedure that I admit I don't have a 100% concrete grasp on, but the way I was told that it works is that is actually spins the individual wavelets of light so that light spinning clockwise goes to one of your eyes, while light spinning counter-clockwise goes to the other eye after being filtered by the glasses. This eliminates the flicker of Active Shutter 3D TVs, and eliminates most of the color filtering of anaglyph (although because there is some light filtration going on, it's not as little color filtering as with Active Shutter 3D TVs). The glasses are cheap to obtain these days, and since there's not a 2D market for these TVs as well, the sets themselves also tend to be priced lower than their active shutter counterparts. The disadvantages of this format are, because only half of the pixels are used in either one of the 3D images, the images themselves are half-resolution when you see them (although I admit, I've never noticed that effect in my own viewings on my passive 3D monitor).

• Autostereoscopic Last is the Autostereoscopic TV. Autostereoscopic is a large word that basically means you don't need glasses to see 3D on it. What these do is, on the TV level, filter the images so that they go to either eye, kind of like those hologram stickers that animate or appear 3D based on how you tilt your head. If you've ever seen items like the Nintendo 3DS, the Fujifilm W3 3D camera, or the HTC EVO 3D, this is what those devices use to create their 3D effect. And yes, there are 3D TVs that use autostereoscopic screens. The biggest advantage is no glasses, and no color filtration. The disadvantages are that it also uses half-resolution because each image is using half the pixels, just like with Passive TVs. It also requires you to be in the very specific spot where your eyes can see both images, with even small alterations to your position ruining the image. Makes it impossible to use autostereoscopic 3D TVs for group viewings, and difficult for individual viewings. Usually these screens are only on handheld devices (like the 3DS) as a result, and the TVs that do use this technology are very expensive.

There are other less common ways to make 3D images (such as the insanely weird ChromaDepth glasses technology that Nickelodeon used in the 1990s) but those 4 are the only 3D TV technologies you're likely to run into today. Most people, when buying a 3D TV, will be trying to decide between Active Shutter and Passive 3D TVs. I would suggest the passive 3D TVs, because most 3D content is broadcast in half-resolution anyway (makes it easier to send the information), and that flicker can be really annoying. There are those who would argue that you should never get passive because you're destroying the image by halfing the resolution. The thing is, most 3D content is already half-resolution. For example, YouTube requires you to upload images in the same resolution that they were originally in, so that they can stretch them. Here's an example I made myself:


The reason YouTube does this is because it matches the standards of television broadcasts. Television broadcasts do this because they literally cannot send two 1080p images across cable lines constantly. They're just too big. So they figure since at least half of the 3D TVs in existence are shrinking the image anyway, shrinking the image is the best way to deal with this.
Admittedly, this leaves Blurays and Video Games, both of which are more or less controlled by Sony, who have bet on Active Shutter 3D technologies for their own implementations. Playstation 3's and other Bluray Players don't have to transport the image over large distances through many cables, so they aren't limited physically by the size of the image as much, allowing them to send two 1080p images to your TV without issue. But the images still work on a Passive 3D TV, so getting one won't prevent you from playing a game or watching your Bluray in 3D.

What I'm basically saying is if you're going to buy a 3D TV, buy a passive 3D TV. Any of its disadvantages will be shared by an active 3D TV in most circumstances, but Active 3D's disadvantages will never be shared with a Passive 3D TV. There are, however, Passive 3D TVs with high refresh rates that will work for both standards, so it's not like you always have to choose (if you're made of money). The difficulty is trying to decide whether or not your TV is, in fact, a passive 3D TV. They call it all sorts of things when it goes to marketing (Theater 3D, Cinema 3D, etc.), which makes it unnecessarily confusing. Basically, the way to tell is to look at the glasses that they want you to use with the TV. If they don't have them there, ask a store rep to show them to you. If they look like they'd work without batteries, you're getting a passive 3D TV.