What is 4K Ultra HD resolution?

Background

The term “4K” (also known as 4K Ultra High Definition, 4K Ultra HD, 4K UHD or just UHD) refers to the resolution of the TV, which is a measure of how much detail you can see. A traditional 1080p high definition TV is limited to 1,920 vertical columns and 1,080 horizontal rows of pixels, while a 4K Ultra HD TV has a total resolution of 3,840 pixels by 2,160. With four times the resolution of 1080p HD displays, 4K offers improvement in picture clarity over existing HD resolutions.

Here are few ingredients that make up 4K Ultra HD:

  • More frames per second (fps)
  • Higher pixel resolution
  • Greater color depth
  • HDR (High Dynamic Range)

Note that some 4K devices may not support all the above ingredient and the capability of their support may also vary. One would need a compatible player, TV and content to have the best 4K Ultra HD experience.

What are frames per second (fps)?

When playing video, “fps” refers to frames per second, also known as frame rate. Each frame is a still image; displaying frames in quick succession creates the illusion of motion or animation. The more frames per second, the smoother the motion appears. The fps is also important for the User Interface, or UI. In general, the frame rate needed to avoid jerky motion during video playback and when using the UI is about 60fps. Images at 60 fps are smoother with more details. The more fps, the sharper the content.

What is pixel resolution?

Your TV is made up of super tiny dots called pixels. These pixels line up like a grid to create images on your TV screen. The more pixels there are, the sharper and more realistic images look. When we can see individual pixels, images look blocky and less lifelike, so we usually prefer displays with a higher resolution, and 4K is very high resolution indeed. That is why it is sometimes known as "Ultra High Definition".

The name 4K comes from the fact that there are roughly four thousand pixels on the horizontal side, which gives 4K four times as high a resolution as 1080p, which is what we normally mean today when we describe a screen as "Full HD".

What is color depth?

“Color depth” refers to the total number of possible colors that can be displayed on a screen. The higher the color depth, the more shades of every color that can be displayed. This results in a richer, more realistic image, coming closer to what the human eye can perceive in the real world.

Full HD (1080p) delivers 8-bit color depth, but 4K Ultra HD makes up to 10-bit color depth possible (dependent on your TV).

What is HDR?

HDR (High Dynamic Range) is a technology supported in higher-end 4K devices and it helps to expand the range of both contrast and color significantly. Bright parts of the image can get much brighter with better color accuracy, while dark parts of the image can get much darker improving the contrast. Overall, the image has a greater "depth". HDR is not strictly a 4K only technology, but today’s HDR TVs are largely also 4K TVs.

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