What Is 4K Resolution?

4K resolution is a display or video format with roughly 4,000 pixels across the image. The name counts the horizontal pixels, unlike 1080p, which counts the vertical lines. On monitors, TVs, laptops and cameras, 4K means 3840 × 2160 pixels in a 16:9 shape, which is why it is also called 4K UHD or 2160p.

That works out at about 8.3 million pixels. It is exactly twice the width and twice the height of full HD (1920 × 1080), so a 4K screen shows four 1080p images in a two-by-two grid.

Cinema uses a slightly wider 4K of 4096 × 2160, set by Digital Cinema Initiatives. Our FAQ on UHD and how it differs from cinema 4K covers the naming in detail. For screens, the two names point to the same 3840 × 2160 panel.

Each step up in resolution multiplies the pixel count, and with it the work for the graphics processor, the data on the cable and the storage for recorded video.

1440p is sometimes marketed as 2K or 2.5K, but it has well under half the pixels of 4K. The QHD format sits between FHD and 4K and is mainly a consumer monitor size.

Whether 4K looks sharper than 1080p depends on pixel density, measured in pixels per inch (PPI), and on how far away the viewer is. The same 3840 × 2160 image gives very different densities on different screens:

On a small HMI read from a meter away, 4K adds cost and graphics load for little visible gain, so 1080p or lower stays common. 4K earns its place on larger screens and where operators read fine detail, such as maps, sensor feeds, drawings and medical images.

Our military monitors include 3840 × 2160 rack mount and chassis models from 15.6 inch (15.6″) to 55 inch (55″), and our marine and medical ranges include 4K UHD models at 23.8 inch (23.8″) and 32 inch (32″). Driving them is rarely a problem: many embedded boards have several 4K outputs, and our 3.5″ SBCs include models with three or four 4K displays from one board.

Software needs checking too. HMI and SCADA screens drawn for 1080p look the same size on a 4K panel at 200% scaling, only sharper, but older applications that are not DPI-aware can appear tiny or blurred once Windows scales them. Before choosing 4K for an operator station, run the actual application at the target scaling and check that every control, trend and alarm banner still reads clearly.

In cameras, 4K usually means an 8-megapixel sensor read out at 3840 × 2160. 4K security and inspection cameras capture enough detail to read a number plate, a label or a defect from further away, or to cover a wider area with one camera.

The extra pixels cost bandwidth. Uncompressed 4K at 60 frames per second is around 12 Gb/s, so a 4K source needs HDMI 2.0, DisplayPort 1.2 or 12G-SDI to reach the computer. HDMI 2.0 capture cards bring a 4K60 feed into an edge AI computer, where it can be recorded at full resolution and scaled or cropped for inference.

Four times the pixels does not mean four times the file size, because video is compressed. A modern codec such as H.265 (HEVC) typically stores a 4K camera stream at somewhere around 8 to 20 Mb/s for surveillance, against roughly 2 to 6 Mb/s for 1080p. Higher frame rates, busy scenes and higher quality settings push the figure up. Our FAQ on how bitrate affects video quality and storage shows how to size a recorder.

For a multi-camera system, the sums add up quickly. Sixteen 4K cameras recording continuously at around 12 Mb/s each fill roughly 2 TB of storage a day, so recording length, codec and drive endurance need planning before the cameras go up. Many systems record the full 4K stream but run AI analytics on a scaled-down copy, which keeps the processing load manageable.

Decoding is the other cost. Playing or analyzing several 4K streams at once needs hardware video decoding in the processor or GPU, which current Intel, AMD and NVIDIA Jetson processors provide for H.264 and H.265.

We supply 4K monitors, capture cards and the computers that drive them as one integrated system, configured and tested together as standard. Tell us the screen size, viewing distance and video sources, and we will recommend the right resolution.