4K UltraHD, also known as Ultra High Definition, Ultra HD or 4K, is a video format conceptualized by the Japanese public broadcasting network, NHK. On October 17, 2012. Ultra HD (4K), or Ultra High Definition, is the next big step in HDTV resolution. The Consumer Electronics Association (CEA) defines an Ultra HD television as one that displays at least 8 million active pixels, with a lower resolution boundary of at least 3,840 by 2,160.
There are multiple varieties of 4K digital content ranging from 3,840 by 2,160 to 4,096 by 3,112, but the 3,840 by 2,160 resolution is the most consistent number we’ve seen and the standard resolution most UHD/4K HDTVs and monitors have settled on. It’s a nice, even number, doubling the horizontal and vertical pixels offered by 1080p (1,920 by1,080 pixels), which itself became the standard for high definition.
Collectively, the format was originally known as 4K, and while the CEA officially changed its designation to Ultra HD (UHD for short), the 4K label appears to be sticking. Either way, this is a different thing from 48-frames-per-second video, which made news last year thanks to Peter Jackson’s The Hobbit: An Unexpected Journey and The Hobbit: The Desolation of Smaug. (For more on those, read ‘The Hobbit’ at 48fps: Frame Rates Explained.)
Depending on the variety (discussed above), 4K generally offers four times the resolution of standard 1080p HDTVs. Even so, 4K content will still be compressed for home use, as an uncompressed two-hour movie playing at 30 frames per second would require 55TB of storage just by itself, according to an excellent post from Michael Cioni, who acted as digital intermediate supervisor on The Girl With the Dragon Tattoo.
4K video also takes a solid 1Gb-per-second connection for reliable playback (unless it’s compressed in some way), which means fast hard drives and faster-than-usual Internet and network connections. The HDMI connections on your current devices might not be enough to show 4K video at its smoothest; most entertainment devices and HDTVs use HDMI 1.4 which supports an Ultra HD picture at 30 frames per second. HDMI 2.0, which is starting to appear on most 4K HDTVs, supports Ultra HD at 60 frames per second. Like the display technology itself, it will take some time for the HDMI standard to become common enough for both HDTVs and media players.