What Is 4K Resolution? Overview and Perspective of Ultra HD

4K Ultra HD is here: What it is and what it means for your TV viewing

4K Resolution Comparison Chart
4K Resolution Comparison Chart. Image courtesy of OPPO Digital

4K refers to one of two high definition resolutions: 3840 x 2160 pixels or 4096 x 2160 pixels. 4K is four times the pixel resolution, or twice the line resolution (2160p), of 1080p (1920 x 1080 pixels) that is one of main current consumer high definition resolution standards. The other high definition resolutions currently are used are 720p and 1080i.

4K is now officially designated for consumer products as Ultra HD or UHD but is also referred to at times, such as in professional or commercial settings as Ultra High Definition, 4K x 2K, or Quad High Definition.

4K resolution is now being employed on an increasing basis in commercial digital cinema projection using the 4096 x 2160 pixel option, where more and more films are shot or mastered in 4K, or upscaled from 2K (1998 x 1080 for 1.85:1 aspect ratio or 2048 x 858 for 2.35:1 aspect ratio).

Also, 4K, under its two official consumer labels, Ultra HD or UHD, is now well established in the home theater environment, using the 3840 x 2160 pixel option, via both a growing number of home theater receivers that have either 4K pass-through and/or 4K video upscaling capability, as well as TVs and video projectors.

Why 4K?

What makes 4K (Ultra HD or UHD) significant is that with the use of ever larger TV screen sizes as well as video projectors, 4K provides much more detailed and less pixel visible images than 1080p. 1080p looks great up to about 80-inches, and can still look good in larger screen sizes, but 4K can deliver an even better-looking image for those larger screen sizes.

Also, 3D TVs currently in use that employ the Passive Polarized method of viewing, resolution of the resultant 3D image is cut to 540p (960x540 pixels) for each eye, which is 1/2 1080p resolution. In comparison, the same TV displays a 2D image in 1080p resolution.

However, by employing a 4K resolution panel or screen, 3D images viewed via Active Shutter Glasses can be displayed with 1080p (1920x1080) resolution for each eye.

The additional bonus is that when viewing 2D images on the same TV, the viewer will see a full 4K resolution image.

How It Is Implemented

There are plenty of 4K Ultra HD TVs available and in use for consumers, as well as a small number of 4K-enabled or 4K-enhanced video projectors. The availability of native 4K resolution content is still thin but it is growing.

4K content is available from several streaming sources, such as Netflix, Vudu, Amazon, and Sony, as well as the introduction of the Ultra HD Blu-ray Disc format and players, is slowly adding to the content list. It is important to note that although there are many Blu-ray disc players that upscale standard 1080p Blu-ray disc to 4K, only an Ultra HD Blu-ray Disc player can play discs that contain a native 4K resolution.

On the cable/satellite part of the equation, DirecTV is able to deliver both pre-recorded and live 4K content via satellite to its subscribers (provided they have both a compatible satellite box and subscribe to the appropriate plan). On the cable side, things are in the works, but nothing substantial yet.

However, over-the-air TV broadcasting is where things are really lagging. 4K TV broadcasting is still being field tested in many ways with South Korea taking the lead, followed by the U.S. However, one big obstacle to adoption is that the electronic infrastructure needed is not compatible with the current HDTV broadcasting system.

For more details on the progress towards 4K resolution TV broadcasting, refer to ATSC 3.0 - The Next Step In TV Broadcasting.

What 4K Really Means for Consumers

The increasing availability of 4K, under the official moniker Ultra HD, delivers consumers a greatly improved video display image for larger screen applications, and can greatly reduce the ability for viewers to see any visible pixel structure on the screen, unless you place yourself extremely close. This means even smoother edges and depth - in fact when combined with faster screen refresh rates, 4K has the potential to deliver almost as much depth as 3D - without the need for glasses.

The implementation of Ultra HD doesn't make a 720p or 1080p TV obsolete (although, as 4K Ultra HD TV sales pick-up and prices some down, fewer 720p and 1080p TVs are being made), and the current HDTV TV broadcast infrastructure will not be abandoned anytime soon, even as ATSC 3.0 begins to become available for use for content transmission.

As Ultra HD is implemented on a wide basis, it will be in addition to, not in place of, current technology, just as 3D is currently. Of course, just as with the 2009 DTV transition, there may come a date and time certain where 4K may become the default standard, but that means a lot of infrastructure needs to be in place, and there must be standardization throughout the entire production and delivery chain, as well as consumer acceptance.

Lean more about 4K implementation in my companion article: What You Need To See 4K Resolution On An Ultra HD TV

If you feel that you are ready to make the jump into 4K, check out my running list of Best 4K Ultra HD TVs.

Beyond 4K and Ultra HD

Yes, they are already thinking beyond 4K – how about 8K? 8K is 16 times the resolution of 1080p. For more on this development, read my article 8K Resolution. Several prototype 8K TVs have been displayed at CES but nothing has developed commercially.

Video Resolution vs Megapixels

Here's how to compare 1080p, 4K and 8K resolution to the pixel resolution of even modestly priced digital still cameras:

  • 1080p (1920x1080) is only 2.1 megapixels.
  • 4K (3840 x 2160 or 4096 x 2160) is about 8.5 megapixels.
  • Only with 8K (7680 x 4320 pixels – 4320p) do you get into the pixel resolution range of the best professional digital still cameras – 33.2 megapixels. In other words, you are most likely taking photos with much higher resolution than you can see on your TV screen when it comes to video content.

Color, Contrast, and More

Of course, all the above being said, you are the one that needs to be satisfied with what you are seeing on your TV screen – resolution is one part, but other factors, such as video processing and upscaling quality, color consistency, black level response, contrast, screen size, and even how the TV physically looks in your room are also factors to take into consideration.

For a more detailed look at how contrast and color are being improved, along with 4K resolution, Dolby Vision and HDR10 and Color Perception and Your TV.

4K is Also Known As: 4K x 2K, Ultra HD, UltraHD, UHD, Ultra High Definition, 4K Ultra High Definition, 4K Ultra HD, Quad High Definition, Quad Resolution, Quad Full High Definition, QFHD, UD, 2160p