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What Is 4K TV?

By , Sean Captain - Source: Tom's Guide US | B 23 comments
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Ready for the latest 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 85 inches (over 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 television manufacturers are launching dozens of 4K/Ultra HD sets this year, the rest of the groups in the industry — broadcasters and programmers — have been slow to adopt the format. That doesn't mean there's no use for the new sets: 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 bestHDTVs today have 1080 lines (1080p).

The term 4K, however, is derived from the movie industry designation 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 (which are 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 a lot 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 oniPhones and iPads, 4K/UHD technology results in smaller pixels compared to HD screens of the same size, which means you'll see a more detailed picture when 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 pronounced 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?

The 4K format is no exception to the rule that new technologies are pricey. It was originally intended for giant TVs, such as Sony's 84-inch Ultra HD set, which cost a whopping $25,000 last year when it was introduced. But prices are coming down quickly.

The 55-inch LG 55LA9650 lists for $3,500.The 55-inch LG 55LA9650 lists for $3,500.Sony's new sets (expected to appear in June this year) span nine new models, ranging from a $2,200 49-inch set to a $9,000 79-inch model. The high-end $25,000 84-incher will still be in the lineup, but Sony clearly wants to push 4K into the mainstream. Samsung is making similar moves with models expected this spring, including a $2,500 48-inch set and a 75-inch model that may see discounts down to $6,000. One 50-inch 4K TV is expected to be priced at $1,000 later this year. 

In spite of the price drops, 4K models are still expensive and command a price premium of 50 percent or more versus comparable, full-featured HDTVs of the same size (and HDTV prices continue to fall, as well). That said, most of the 4K panels are based on LCD displays, a well-developed and mature technology. So 4K prices may continue to decline as the 2014 holiday shopping season approaches.

What can I watch on a 4K TV?

Not much, yet, beyond regular HD that the TV can upconvert. There are no broadcast outlets in the United States supporting 4K/UHD 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 GB 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.

As for home movies, JVC was the first to introduce a 4K camcorder for roughly $5,000. Panasonic will add 4K video recording to some of its digital cameras coming later this year. And Sony, as you may have suspected, is pushing Ultra HD in a big way, including a $2,000 4K camcorder, also coming later this year. The company will also add 4K video capture to its new Xperia Z2 smart phone. 

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. If you are considering a 4K set, how well it upscales should be the deciding factor. Some models do an outstanding job using full-array LED technology to better bring out the extra detail, for example, while others produce upscaled video that looks duller than some conventional HD pictures.

When will more 4K content be available?

A smattering of 4K content is available now, with more coming later this year. The difficulty arises because there is no easy way to deliver 4K programs. 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.

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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 the end of 2014, by which point there will likely be Blu-ray discs of 100GB or greater capacity.

Furthermore, 4K will require even more Internet bandwidth. So Netflix plans to start streaming the format this year using a newly minted compression format to squeeze 4K video through existing broadband connections. Called HEVC or High Efficiency Video Coding, the new compression method works only with compatible new TVs. New Ultra HD sets coming out this year from several manufacturers, including LG, Samsung and Sony, will support HEVC. No set-top boxes, such as Apple TV or Roku, support 4K yet. Netflix will offer its series "House of Cards" in 4K, as well as some documentaries to start, but for the best picture, a 15 Mbps or faster Internet connection is required.

Further compounding the compatibility problem for existing hardware is that a standard connection from a hard drive or an 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 were sold last year do not, and will not, support HDMI 2.0 (or HEVC), 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 the majority of consumer electronics companies to build HDMI 2.0 support into new products such as A/V receivers. (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?

Clearly, the secret is to better compress the video, using algorithms to cram more detail into less data, while also 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.

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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, so it actually delivers a better picture. The new HEVC compression algorithm, also known as H.265, can 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. Netflix will be the first to offer such 4K programs, but remember that you'll also need an HEVC-compatible set to enjoy the picture.

What comes after 4K?

While 4K is far from ready for prime time (literally), its successor, 8K, is already on the drawing board. And several TV manufacturers have already demonstrated 8K prototype sets. All the problems of delivering 4K to a TV become that much harder when you're trying to provide enough detail to fill 8K television'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 said off-the-record that they may forgo 4K altogether and wait for 8K before upgrading.

Follow John Quain @jqontech. Follow Sean Captain @seancaptain and on Google+. Follow us @tomsguide, on Facebook and on Google+.

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  • 0 Hide
    josejones , November 21, 2013 8:55 AM
    I'm glad 4k is coming but, I'd prefer TRUE 4k at 120 FPS with G-sync for gamers. One problem is that HDMI 2.0 cables and Blu-Ray may not cut it. Blu-Ray is currently limited to 8 channel audio instead of the new 32 ch. Of HDMI 2.0's 18 Gb/sec bandwidth, only 14.4 Gb/sec is usable due to a 20% overhead. HDMI 2.0 will NOT handle 120 FPS.

    I may wait for 8k TV but manufacturers, HDMI and Blu-Ray have all got to get it together.
  • 1 Hide
    officeguy , November 21, 2013 9:11 AM
    Well, I am 36. Most of my generation, their parent said "Don't sit so close to the TV, it will ruin your eyes". Now its "It's good to sit closer because the picture is bigger and clearer." What should I do?
  • 0 Hide
    alchemy69 , November 21, 2013 9:12 AM
    A sales gimmick designed to prey on weak minded idiots who assume that more equals better.
  • Display all 23 comments.
  • 0 Hide
    DeadRam , November 21, 2013 9:15 AM
    4K is useless since TV broadcasts are 720P, 4K movies won't fit on current Blu-ray media and Next gen consoles can't even render games at 60 FPS 1080p.
  • 0 Hide
    d_kuhn , November 21, 2013 9:39 AM
    I just ordered a 4k 31.5" monitor(Asus PQ321Q)... and there are a number of gotcha's when you're looking at 4k. The big one is interface... HDMI 2.0 will only deliver 30hz... and many of the 4k displays out there are limited to 30hz. The Asus can do 60hz but only by using 2 cables and splitting the screen into what windows thinks are 2 separate monitors. If you can wait then I'd suggest holding out for HDMI 3.0, which will have plenty of bandwidth for 4k.

    Playback is even more limited... not much out there can drive a 4k display yet so most of the folks I've talked with are using PC's with high end graphics cards. You will need one of the newest/higher cost cards to even get to 30hz (we've been using Titan's but I just ordered the R9 for the Asus - apparently less issues running 4k)

    On the plus side... if you're willing to deal with a 30hz panel then there are some low cost options. Seiki has 2 displays in the $1k range... up to 55".
  • 0 Hide
    clonazepam , November 21, 2013 9:54 AM
    I like how the render at the bottom isn't to scale so it looks like you have to have 4K in order to sit at an appropriate distance from the television. The scale is so horrible, they make it appear as though proper viewing distance for 1080p is only achieved by being on the opposite end of the room lol
  • 0 Hide
    Innocent_Bystander , November 21, 2013 10:13 AM
    3 screen heights from 1080P is rubbish. You can't see pixels until you get as close as 1 screen height, even then you have to have pretty good eyes.

    The hype machine for 4K is revving up... time to tune out for the next... umm... 5 years?

  • 0 Hide
    dilbert , November 21, 2013 10:18 AM
    Good article.

    One little thing: in the "4K IS A CONFUSING TERM" section, it says 3140x2160 instead of 3840x2160.
  • 0 Hide
    jobadiah , November 21, 2013 10:25 AM
    @clonazepam, I know right. 3.7 feet away, your knees would almost be touching the wall. I couldn't sit that close to a 60 inch screen just for the fact it would be like sitting in the front 1/3 of a movie theatre; you are too close to see everything without looking around. Plus, you can only fit so many people around the TV at that distance. Sitting 2 feet away from my 24" monitor (11.5" vertical) I can't really see pixels. Any bigger screen and I would probably sit farther back.
  • 0 Hide
    jobadiah , November 21, 2013 10:26 AM
    @clonazepam, I know right. 3.7 feet away, your knees would almost be touching the wall. I couldn't sit that close to a 60 inch screen just for the fact it would be like sitting in the front 1/3 of a movie theatre; you are too close to see everything without looking around. Plus, you can only fit so many people around the TV at that distance. Sitting 2 feet away from my 24" monitor (11.5" vertical) I can't really see pixels. Any bigger screen and I would probably sit farther back.
  • 0 Hide
    hannibal , November 21, 2013 10:38 AM
    In many test in here FInland they have found out that upscaled 1080p picture is so much better than normal HD picture, if you are just willintg the pay the deep price of 4K screen. So I would not be worried about content at this moment. They did say that real 4K content did look better, but upscaled will be just fine in the mean time!
  • 0 Hide
    Jim90 , November 21, 2013 10:43 AM
    "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"

    --> Exactly!! we can't even get 1080p streamed so, even with compression - and it better be lossless - how the hell can 4k be streamed.

    Still, that's some nice real estate for desktop productivity apps.
  • 0 Hide
    Dirk_Funk , November 21, 2013 10:52 AM
    I hope there aren't any engineers reading the comments here. Some of the commenters sound so spoiled... yes there are some things holding 4k back right now but jeeze it takes time to make products that do the job right AND can be mass produced AND will be cheap enough for consumers AND will actually have enough of consumers attention to justify selling the product in the first place. I mean look at pc gaming at 4k, you have to pay at least 1000 dollars on gpu's alone just to get 60 fps at high settings. This is clearly future tech and if I have to wait for the future to get it and have it run right then so be it!
  • -1 Hide
    Gurg , November 21, 2013 11:13 AM
    Personally I'm tired of discs that get scratched, wasting money on DVD/BlueRay players that die and don't want an enhanced 4k BlueRay. Those are obsolete technology.

    I want to buy a personal media license to access books, movies, music etc from the cloud and download with fast internet connection and possibly using my PC as temporary storage and media playback controller interface. More of the Steam and Amazon Kindle for books model. .
  • 0 Hide
    techguy911 , November 21, 2013 11:24 AM
    4K tv's are a huge waste of money it's like buying a blu-ray player in 1995 there is no content that will support 4k for at least 5 years, cable still maxes out at 720p and even blu-ray discs are not large enough to handle true 4k.
    A real true 4k source movie size for 2 hours would need 500gb those Sony mastered in 4k video are 4k down converted to 1080p.
  • 0 Hide
    smiley4julie , November 21, 2013 11:37 AM
    Also do not forget, With 4K Passive 3D, 1080p 3D looks amazing mostly because you do not loose resolution with the interlacing, with cheap glasses and no headache. Normally I get nauseous and headaches with 3D TV. But not here it was fantastic.
  • 0 Hide
    mi1ez , November 21, 2013 1:54 PM
    720p ISN'T just another way to describe a res with 720 scanlines. The p is for progressive rather than interlaced 720i which affects the way the frame is refreshed. Same with 1080p/1080i.
  • 0 Hide
    smiley4julie , November 21, 2013 4:36 PM
    mi1ez, that's a fair point and true. I was meaning something else, the left eye and right eye are interlaced to a lower resolution. So left eye gets half of 1080progressive, every odd line, and the right eye gets the other half of the 1080progressive, every even line. Effectively halving the horizontal resolution, (passive 3D). So maybe interleaved is a better description. And with 4K, half the resolution is still 1080p per eye. Unless I misunderstanding how the passive 3D works. Either way the end result just looks better.
  • 0 Hide
    Hupiscratch , November 21, 2013 6:39 PM
    A wider view on the UHD format is shown by the FlatPanelsHD guys:
  • 0 Hide
    immanuel_aj , November 22, 2013 2:16 AM
    @smiley4julie. Not quite. Let me call 4K 2160p for a moment. When using it for 3D, you're actually getting half of 2160p in each eye, which would be 2160i. 1080p is 1/4 of the resolution of 2160p, while 2160i would be 1/2.
    (2160i = 3840 x 1080)
    (1080p = 1920 x 1080)
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