Ready for a new buzzword? 4K is the biggest thing in TV nowadays — literally. This format offers four times the resolution of HDTV, and is designed especially for very large TVs, some with screens as large as 80 inches (nearly 7 feet from corner to corner, measured diagonally). That said, manufacturers are building 4K resolution into smaller sets, currently down to 39 inches.
4K (also known as Ultra HD or UHD) is supposed to be the next step up from HD. But while manufacturers promise to launch more 4K/Ultra HD sets soon, the rest of the industry — broadcasters and programmers — has been slow to adopt the format. But that doesn't mean there's no use for them: All 4K TVs upscale regular HD content for an Ultra HD viewing experience, so you have plenty to watch on a 4K/UHD TV right now.
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Let's look at how 4K works and what's needed to make it work better in the future.
What does 4K mean?
The term is not obvious, or intuitive. Since mass market TVs debuted, their screens have been defined by the number of horizontal lines in the picture. Most old tube TVs (and some early flat screens) had a "standard definition" of 480 lines — which didn't allow for a lot of detail. Entry-level HDTVs have 720 lines, known as 720p, and the best HDTVs today have 1080 lines (1080p).
4K, however, is a term derived from the movie industry for the professional format of 4096 x 2160 pixels, and refers to the roughly 4,000 pixels across the screen.
What is Ultra HD or UHD?
Consumer electronics equipment uses a slightly lower resolution than 4K. Known as Ultra HD or UHD, this format measures 3840 x 2160 pixels and is exactly four times the pixel count of full-HD 1080p TVs (1920 x 1080 pixels). Regardless, the 4K TV designation has stuck, even for describing the slightly lower-res consumer electronics format.
What's the benefit of 4K?
With 4K TVs, you get lots of detail. At 4K, a cityscape may allow you to see individual windows in the buildings, for example, and even the people on the ground walking in and out of the skyscrapers.
Just like the Retina display on iPhones and iPads, 4K/UHD technology results in smaller pixels compared to HD screens of the same size, which displays a more detailed picture when you're sitting up close. You can't press your nose to a 4K TV, but you can get about twice as close as you can to a 1080p TV of the same screen size, without seeing the grid of individual pixels. That's important for very large screens, whose pixels would be comparatively huge at 1080p resolution, but just a quarter of the size at 4K/UHD.
How close can I sit to a 4K TV?
According to the International Telecommunications Union, which sets many technical standards, people can sit twice as close to a 4K/UHD TV (1.5 times the height of the screen) as to an HDTV (three times the screen height) of the same size. Whether most people will actually sit closer remains to be seen. At typical living-room distances, the advantages of Ultra HD are less noticeable.
The difference between 4K and regular HDTV is most noticeable on very large screens. Sharp, for example, makes a 70-inch diagonal (approximately 34.3 inches, or 87 centimeters, high) 4K TV. You could sit just 4.3 feet (1.3 m) away from this model, vs. 8.6 feet (2.6 m) from Sharp's 70-inch HDTV.
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At smaller sizes, though, 4K/Ultra HD is less helpful. With Sony's or Samsung's 55-inch 4K TVs, for example, you could sit just 41 inches away, but that's awfully close. Getting that much closer might be appealing to some people, such as gamers, but none of the current game consoles, including the new PlayStation 4 and Xbox One, support 4K games. In its official PS4 FAQ, Sony says only that 4K output "is in consideration." Microsoft told Tom's Guide that the Xbox One, "will support 4K games and entertainment" via a software upgrade. But Microsoft did not say when the upgrade would come. In fact, many games aren't even in 1080p, or don't play in 1080p at the 60 frames per second gamers prefer.
How expensive are 4K TVs?
4K TV is no exception to the rule that new technologies are pricey. Originally intended for giant TVs, Sony's 84-inch Ultra HD set costs a whopping $25,000. Even somewhat smaller models come at a premium — Samsung's and Sony's 55-inch 4K models cost about 50 percent more than their top-end HDTVs of the same size ($3,500 to $4,000). That said, current 4K panels are based on LCD displays, a well-developed and mature technology. Prices started dropping just a few months after the first models debuted and will likely fall rapidly in the next year.
What can I watch on a 4K TV?
Not much. There are no broadcast outlets in the U.S. supporting 4K/UHD yet and no movies available on disc. You will find some 4K shorts on YouTube, and Sony is selling a $700 Ultra HD 2TB player that downloads videos overnight. However, the Sony FMP-X1 player has access to fewer than 200 items — movies and individual TV show episodes — available via Sony's online service. It also requires a long download time — a two-hour movie runs 30 to 40 GB, and you can't start watching until the entire file is downloaded. Furthermore, the service and player work only with Sony's Ultra HD sets.
Aside from those limited options, most of what you can watch on a 4K TV is HD programming that has been scaled up to Ultra HD. Essentially, the TV's processor guesses which details would fit in a higher-resolution picture. (It's the same process that allows DVDs, which are standard resolution, to appear on an HDTV.) Upscaling won't reveal a jagged, pixelated image, but depending on the set, you may discern some pixel crawl (a staticlike appearance), or even a bit of fuzziness around fast-moving subjects as the TV's processor struggles to fill in the extra pixels.
When will more 4K content be available?
A smattering of 4K content is available now, and more will be coming in 2014. For now, there is no easy way to deliver 4K programs, because in theory, they have four times the data of HD, which means they could require four times the bandwidth (although new video-compression schemes are expected to significantly reduce those demands).
Such data rates are impractical for current broadcast TV (over the air or via cable or satellite), which, with a few exceptions, doesn't even deliver full-HD 1080p resolution for most channels. (Instead, most stations come across in the 720p format or alternating, interlaced 540-line video frames called 1080 interlaced, or 1080i). Therefore, supporting Ultra HD would require broadcasters to make system-wide upgrades.
Today's Blu-ray discs can store up to 50GB, which probably won't be enough for 4K/Ultra HD video. Estimates for a two-hour movie range from 30GB to more than 100GB depending on what compression technology is used. A new Ultra HD-capable Blu-ray specification isn't expected until sometime in 2014, by which point there will likely be Blu-ray discs of 100GB or greater capacity.
Furthermore, 4K video won't stream via most Internet connections in the U.S. In spite of this current limitation, Netflix is experimenting with streaming the format. In a September 2013 interview, Netflix CEO Reed Hastings said that streaming 4K will require a 15 Mbps Internet connection and that the company will begin offering 4K streams in 2014.
However, even the standard connection from a hard drive or AV receiver to a TV can't technically handle the data demands of 4K. There is a newly minted HDMI 2.0 specification to handle Ultra HD, but only a few new products support it. Even some Ultra HD sets that have been sold do not, and will not, support HDMI 2.0, so they will have to display video at a slower-than-optimal 24 frames per second.
The new HDMI connection will support Ultra HD at the standard digital TV frame rate of 60 fps, but it will take time for consumer electronics companies to build HDMI 2.0 support into new products. (Sony and Toshiba have said that some of their products will be upgradable through firmware updates, and Samsung will sell an updated receiver module that users can swap in.)
What will it take to make 4K work?
The secret is to compress the video, using algorithms to cram more detail into less data, as well as throwing out some detail that viewers would be unlikely to see. Most broadcast and cable TV systems use an older compression technology called MPEG-2, which does not provide enough compression to manage Ultra HD.
Some satellite providers and Blu-ray discs use a version of the newer MPEG-4 standard called H.264. This technology can compress about twice as much data as MPEG-2 and deliver a better picture. The new high-efficiency video coding (HEVC) compression algorithm, also known as H.265, could further compress the video by a factor of two, essentially making it the same as an HD video using the old MPEG-2 standard that most cable companies still use. However, such codecs require new hardware support, so don't expect to see it in widespread use anytime soon.
What comes after 4K?
While 4K is far from ready for prime time (literally), its successor, 8K, is already on the drawing board. All the problems of delivering 4K to a TV become that much harder when you're trying to provide enough detail to fill 8K's 7680 x 4320 pixels. However, given the investment necessary for studios and broadcasters to upgrade (some only recently finished installing HD equipment), many networks have been saying off-the-record that they may forgo 4K altogether and wait for 8K before making upgrades.