Just when you thought it was safe to buy a 1080p HDTV, along
comes another new video format. In fact, you may have seen a number of
new TVs, camcorders, and other products sporting a 4K logo, and movies
shot in 4K have been playing at movie theaters for years. But what
exactly does 4K mean (aside from the stock memory in a Radio Shack TRS-80,
for the aging geeks like me in the audience)? Is 4K something you can
get today, or at least soon enough that you should hold off on buying,
say, an HDTV or Blu-ray player? Is it something you'd even want? Here's everything you need to know about 4K—for now, at least.
What Is 4K?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.)
How Is 4K Different Than 1080p?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.
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