What is 4K Ultra High Definition TV?

Learn about the new technology that provides four times the resolution of a typical HDTV


Steve Kindig

Steve Kindig has been an electronics enthusiast for over 30 years. He has written extensively about home and car A/V gear for Crutchfield since 1985. Steve is also a volunteer DJ at community radio station WTJU, where he is a regular host of the American folk show "Atlantic Weekly," as well as the world music program "Radio Tropicale."

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Samsung 55HU8550

Ultra High Definition TVs have started a high-resolution revolution. These Ultra HD TVs have four times the picture resolution of regular “full HD" 1080p TVs, and can display much more detail. Ultra HD TVs are often referred to as “4K" TVs, because they have a horizontal resolution of around 4000 pixels.

You've probably seen a movie in 4K without even realizing it — 40% of movie theaters use 4K digital projectors to display Hollywood’s latest hits with maximum detail and depth. Now, imagine how lifelike watching at home would be with that many pixels on a 55", 65", or 85" screen instead of a 30-foot theater screen. That's the reality of 4K Ultra High Definition TV.

More pixels = more picture detail

Whether it's a TV, a tablet, or a smartphone, the more pixels a screen has, the more seamless and detailed the picture will look. The ideal is a screen where the "pixel structure" is invisible. You already find that on high-end tablets and phones like those with Apple's "Retina" display. 4K Ultra High Definition models take television a giant step in that direction — you have to stand right next to an Ultra HD TV to notice any pixels at all. Because the picture is so clear and sharp, you can actually sit closer to a 4K TV even if the screen is larger than your old TV. And that adds even more to the sense of immersion.

4K picture resolution vs. 1080p

4K Ultra HD TVs have four times as many pixels as a 1080p HDTV, for a picture that's incredibly clear, detailed, and lifelike.

How close should you sit to a 4K TV? Most experts say you can get as close as 1-1/2 times the screen height, versus 3 times the screen height for a 1080p TV. That's much closer than most of us sit when watching HDTV, but it really transforms the experience — the screen completely fills your field of vision, making you feel more like you’re in the scene. A darkened room and surround sound will further intensify this feeling of immersion.

How much 4K content is available?

Sony FMP-X10

Sony's FMP-X10 4K Ultra HD media player.

4K TVs have quickly become popular, but there's still a limited amount of true 4K content to watch. The same thing happened with the introduction of DVD, HDTV, and Blu-ray — the hardware arrived first, followed by the content. Sony offers an Ultra HD media player, the FMP-X10, that lets you download titles from Sony's online library of 4K films, for rental or purchase. The FMP-X10 also has the ability to play streamed 4K content from Netflix®, making it especially valuable to owners of 2013 Sony 4K TVs, which lacked that capability.

Samsung UHD Video Pack

Samsung's 4K Ultra HD media player.

Samsung also makes a 4K media player, called the UHD Video Pack. If you own one of Samsung's 2014 4K Ultra HD TVs, this is a great accessory. It's a 1-terabyte hard drive that comes pre-loaded with several full-length movies and nature documentaries, all in full 4K resolution. Once you plug it into the TV's USB input, the player's menu appears on the TV screen, and you can navigate and make selections using the TV remote.

Netflix launched their 4K streaming service last year with their original series House of Cards. They've since beefed up their 4K offerings with the complete Breaking Bad series, The Blacklist, as well as their home-grown Marco Polo series. To watch Netflix in 4K, viewers will need a 2014 Ultra HD TV with HEVC decoding, a Netflix 4K streaming subscription (currently $12.99/mo.), and reasonably fast Internet service — at least 20Mbps. Amazon recently joined the 4K club with the launch of a streaming service that, initially anyway, is only available — for free! — to Amazon Prime members.

Two more 4K video sources launched at the tail end of 2014. DirecTV's 4K Ultra HD service offers a limited selection of 4K movies available on a pay-per-view basis. In order to use the service, you must not only be a DirecTV subscriber, but must also have DirecTV's Genie whole house HD DVR, along with a DirecTV-ready Ultra HD TV, such as Samsung's 2014 Ultra HD models. And Comcast announced their Xfinity in UHD, which is also an on-demand service that initially only works with 2014 Samsung 4K TVs.

YouTube has an eclectic and growing library of millions of 4K video clips. While you probably won't find your favorite movie or TV show, there is plenty of 4K eye candy, including some wonderful nature documentary footage. In the meantime, if you have a camera with at least 8-megapixel resolution, then you have a source for 4K photos.

Sony's 4K X-reality Pro upconversion

How will my current video sources look on a 4K TV?

Don't worry if you don't have access to any 4K video sources right away. All 4K TVs include built-in 4K upconversion, also called "upscaling," which takes the video signals from your Blu-ray player, satellite or cable TV box, or game console, and makes them fill the 4-times greater pixel count of the 4K screen. Without upconversion, a 1080p Blu-ray signal would appear as a small rectangular image at the center of the screen, with black bars on all sides. While upconverted 4K isn't the same as true 4K, the processing enhances the appearance of non-4K video to more closely resemble 4K.

Why aren't 4K TVs available in smaller screen sizes?

Most people find that 1080p resolution looks fine on screens 50" or less. From a typical viewing distance you won't notice the screen's grid of pixels — sometimes called the “pixel structure." But 55" and larger screens benefit from a much higher pixel count, making the grid virtually invisible. Ultra HD not only offers a more detailed picture, but also allows you to sit closer to a screen and/or view a larger screen while enjoying unprecedented clarity.

Sony 4K Ultra High Definition TVs

Sony XBR-55X850B

Sony has more 4K experience than any other TV maker. They build professional 4K cameras and cinema projectors, and Sony Pictures has a bigger catalog of 4K films than any other studio. This end-to-end approach helps ensure a truly theater-like experience at home.

Samsung 4K Ultra High Definition TVs

Samsung UN55HU9000

Samsung's curved-screen HU9000 series TVs offer versatility and future-readiness, in addition to an elegant look. A feature called Smart Evolution lets you upgrade the TV's main processor, graphics processor, and memory – to support future UHD formats as they evolve.

LG 4K Ultra High Definition TVs

LG 55UB8500

LG's UB8500 series models are among the most affordable Ultra HD TVs we've seen from a top-tier brand. Like most 2014 4K TVs, this one includes "HEVC" decoding, which means it can display streamed 4K Netflix content with no additional gear needed.

Sharp 4K Ultra High Definition TVs

Sharp LC-60UD27U

Sharp's UD27U-series models are among the few TVs that have earned THX® 4K certification. Getting THX certified has never been easy, but to be 4K-certified, this TV had to pass over 400 rigorous laboratory tests — for both HD and 4K picture quality.

The era of 4K Ultra High Definition TV has achieved lift-off. Stay tuned for further developments.