Just when you thought you had safely gotten up to speed with a brand new 1080p 3D TV… the market is yet again shifting. This time, television makers are pushing the next big thing: 4K televisions. Very loosely, you can think of 4K TV as doing for HDTV what Apple’s so-called “Retina” displays have done for the iPhone, iPad, and MacBook Pros: essentially quadrupling the number of pixels used to display content, delivering a sharper, clearer, and more immersive image.
But do consumers really need another next big thing? After all, consumer adoption of Blu-ray content has been lower than the industry hoped as consumers increasingly rely on their broadband Internet connections to access television and movie content. And the last next-big-thing—3D HDTV—has failed to resonate with the mass market, thanks to the annoyance of wearing 3D glasses and a dearth of quality 3D content.
Is 4K just another technology gimmick? Or is it really the threshold of a new standard for video entertainment?
What exactly is 4K?
The definition of 4K television depends on who you ask, but boils down to a digital video resolution with a horizontal dimension approximately 4,000 pixels across. The most common definition for 4K high-definition television — sometimes dubbed Quad Full HD or 4K UHDTV, for ultra high-definition television — is 3,840 pixels by 2,160 pixels — exactly double the dimensions of a standard 1080p high-definition display.
(3,840 × 2,160 resolution)
That seems like an incredible amount of resolution — and it is. A 4K UHDTV display has 8,294,400 pixels. An eight megapixel display might not seem incredibly high-tech when inexpensive point-and-shoot cameras these days routinely boast resolutions of 10, 12, and 14 megapixels, but it’s important to put that 4K resolution in context. Check out how a 4K display compares to the size of other 16:9 video formats:
One possible point of confusion is that the 4,000-ish pixels in a 4K display are measured horizontally, where the 1,080 (or 720) pixels on an HDTV display are measured vertically. A 4K display is double the width of a 1080p high definition display (which are 1,920 pixels across) and offers four times as many total pixels, but it’s not four times taller.
The 3,840 by 2,160 resolution is the only resolution possible for 4K displays: Folks might also see references to 4K displays running at 4,096 by 2,160 pixels (that 4,096 number is one of those powers-of-eight numbers computers love). For the most part, however, those will be limited to professional digital cinematography.
Isn’t 4K the same as movie theaters?
A common argument in favor of 4K resolution for high-definition displays is that it finally offers a way to bring home movies at the same resolution they’re shown in theaters. That’s kind of true.
There are four primary resolutions for digital movies shown in theaters, they’re all pretty close to 4,000 pixels across. The narrowest resolution 4K digital format is “Academy 4K,” which uses a 4:3 aspect ratio instead of the widescreen 16:9 or 16:10 ratio, so it’s only 3,656 pixels across. That’s narrower than a 4K TV! However, the aspect ratio means the format actually has 9.74 million pixels in each frame — that’s more pixels than the 4K UHDTV format can handle. The “good” news is that most people won’t have to worry about this ratio, although there are still occasional releases like last year’s multiple Academy Award winner The Artist.
In fact, all the current digital cinema formats are at resolutions that 4K UHDTV televisions with a 3,840 by 2,160 resolution can’t handle natively. They range from just a hair larger (3,996 by 2,160 pixels) to a fair bit larger (4,096 by 3,112 for “full aperture” 4K digital movies). So, purely at a physical level, 4K displays do not offer a one-to-one correspondence with the high-resolution digital movies shown in theaters.
Where’s the 4K content?
The fact 4K TV can’t physically show the same content as 4K movies sent to theaters is just part of the equation. After all, by the time consumers get their hands on movies for 4K televisions, what they’re watching will be even more-removed from the in-theater experience thanks to video compression.
At 4K resolution, a 90-minute movie running at 30 frames per second would require more than 3.6 terabytes of storage. That’s part of the reasons studios tend to ship digital movies to cinemas on physical hard disks.
Putting that amount of data on Blu-ray discs would mean a single 4K movie would take up more than 200 Blu-ray discs — not an experience most consumers would be willing to endure. So, when preparing 4K movies, studios will do more than adjust the display size to match 4K televisions: They will also apply copious amounts of video compression. That could be reduced a bit by new Blu-ray formats. For instance, Blu-ray discs are designed to support up to eight layers, which would reduce the number of discs required to hold a 4K movie to about 50 discs. Of course, people would also need a new player: No Blu-ray players on the market today support eight-layer discs, so that’s kind of a non-solution.
OK, so what about streaming? Right now, the Digital Cinema Initiatives specs call for applying enough compression to get 4K movies down to a size where they can play back smoothly on channels capable of handling 250Mbps. (That’s scheduled to be increased to 500Mbps within the next few years.) The good news is that 250 Mbps is well within the reach of common peripheral connections like USB 2, and newer technologies like HDMI, USB 3, FireWire 800, and Thunderbolt can all handle 500 Mbps with aplomb. However, 250 Mbps is quite a lot more than most home broadband connections can handle. Although some cable and fiber installations offer packages that approach that capacity (and Google’s Kansas City experiment will offer 1 Gbps), most consumers will not be able to meaningfully stream or download significant amounts of 4K content unless they start pulling in their movies several hours (or days) ahead of time… and have no worries about bandwidth caps. Video compression can substantially reduce that bandwidth burden, and probably make streaming 4K video possible on connections capable of sustaining 16Mbps to 32Mbps. However, that’s still beyond the reach of most Americans’ home broadband.
That said, small amounts of 4K content are available. Believe it or not, the top resolution YouTube supports is 4,096 by 3,072, and a few experimental films and samples are available (check out YouTube’s 4K playlist). Sony has a list of movies it has released in 4K format, but good luck getting your hands on them if you’re not a commercial theater.
This means, for practical purposes, even folks with the money to buy early 4K televisions or projectors are going to be watching a lot of content intended for “normal” 1080p or 2K systems that is being dynamically upscaled for a 4K display. Ironically, one place where 4K adopters will be able to find high-resolution content is right on their home networks. After all, most of their digital cameras shoot images at resolutions greater than 8.3 megapixels, and a growing number of camcorders and other video devices (like the Canon EOS C500) can capture 4K video. But, of course, few of us have can put the same resources into our homegrown 4K content as Academy Award-winner directors and major Hollywood studios.
Is 4K that much better?
Whether a 4K television is significantly better than standard high-definition content is, ultimately, a judgement call. The answer will depend on how people plan to use their televisions, and (of course) on the content available.
At first glance, it seems like a no-brainer that a 4K display would offer substantially better image quality than a standard HDTV — after all, it’s got four times as many pixels! However, that advantage is only significant with 4K content. Otherwise, the systems are only upscaling lower-resolution content, and likely trying to interpolate it for the 4K system, for better or worse.
At the high end, 4K displays (and 4K content) seem to offer substantial quality advantages at large sizes. There’s a reason why some of the first 4K devices on the market are projectors and giant 84-inch monsters like the Sony XBR-84X900. Public venues, sports bars, and home theater fans who need everything as large as possible — or at least 60 inches or more — will undoubtedly be the first to adopt 4K technology enthusiastically.
It’s not clear how well 4K technology will scale down to sizes more comfortable in everyday living rooms like 45, 40, or even 35 inches. The handful of folks who have embraced 3D HDTVs may well be interested in smaller-size 4K displays since they’re capable of delivering four times as many pixels to each eye, which should translate to a more-convincing 3D effect. However, folks considering screens 40 inches and under may be hard-pressed to see any significant difference between a 1080p display and a 4K display, especially if they’re back a reasonable distance from the screen. Up close, 4K displays will look fabulous — and if prices come down enough they’ll certainly find use as computer monitors.
But the good news is that there’s no rush. Right now, 4K is strictly for early adopters with plenty of cash. Until Hollywood figures out a way to deliver significant amounts of 4K content to consumers, the rest of us can continue happily using our current HDTVs.