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Pixels = Tinyareas(dots)making up a computergraphicpicture.
The name "4K resolution" refers to a horizontal resolution of approximately 4,000 pixels. The use of width to characterize the overall resolution marks a switch from previous television standards such as 480i and 1080p, which categorize media according to its vertical dimension. Using that same convention, 4K UHD would be named 2160p.[4]
There are two main 4K resolution standards:
- The DCI 4K resolution standard, which has a resolution of 4096 × 2160 pixels (256:135, approximately a 1.9:1 aspect ratio). This standard is widely respected by the film and video production industry.[5] The DCI 4K standard has twice the horizontal and vertical resolution of DCI 2K.
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UHD-1, or ultra-high-definition television (UHDTV), is the 4K standard for television and computer monitors. UHD-1 is also called 2160p[6][7] since it has twice the horizontal and vertical resolution of 1080p.[6] It has a resolution of 3840 × 2160 (16:9, or approximately a 1.78:1 aspect ratio). UHD-1 is used in consumer television and other media, e.g. video games.
Many manufacturers may advertise their products as UHD 4K, or simply 4K, when the term 4K is traditionally reserved for the cinematic, DCI resolution.[7][8][9] This often causes great confusion among consumers.[7][10]
YouTube and the television industry have adopted UHD-1 as their 4K standard, and UHD-2 for NHK/BBC R&D's 7680×4320 pixel UHDTV 2 with their basic parameter set is defined by the ITU BT.2020 standard.[11][12][13] As of 2014, 4K content from major broadcasters remains limited.[14] On April 11, 2013, Bulb TV created by Canadian serial entrepreneur Evan Kosiner became the first broadcaster to provide a 4K linear channel and VOD content to cable and satellite companies in North America.[15][16][17][18] The channel is licensed by the Canadian Radio-Television and Telecommunications Commission to provide educational content.[19] However, 4K content is becoming more widely available online including on YouTube, Netflix and Amazon.[20][21] By 2013, some UHDTV models were available to general consumers in the range of US$600.[22][23] As of 2015, prices on smaller computer and television panels had dropped below US$400.[24] DVB expects UHD-1 Phase 2 services to be introduced by broadcasters from 2017, with features such as High Dynamic Range (using HLG and PQ at 10 or 12 bits), Wide Color Gamut (BT. 2020/2100 colorimetry), and High Frame Rate (up to 120 Hz). [25]
History[edit]
Samsung UN105S9 105 inch ultra-high-definition 4K television.
The first commercially available 4K camera for cinematographic purposes was the Dalsa Origin, released in 2003.[26][27] YouTube began supporting 4K for video uploads in 2010 as a result of leading manufacturers producing 4K cameras.[28] Users could view 4K video by selecting "Original" from the quality settings until December 2013, when the 2160p option appeared in the quality menu.[29] In November 2013, YouTube started to use the VP9 video compression standard, saying that it was more suitable for 4K than High Efficiency Video Coding (HEVC); VP9 is being developed by Google, which owns YouTube.[28]
The projection of movies at 4K resolution at cinemas began in 2011.[30] Sony was offering 4K projectors as early as 2004.[31] The first 4K home theater projector was released by Sony in 2012.[32]
Sony is one of the leading studios promoting UHDTV content, as of 2013 offering a little over 70 movie and television titles via digital download to a specialized player that stores and decodes the video. The large files (~40GB), distributed through consumer broadband connections, raise concerns about data caps.[33]
In 2014, Netflix began streaming House of Cards, Breaking Bad,[34] and "some nature documentaries" at 4K to compatible televisions with an HEVC decoder. Most 4K televisions sold in 2013 did not natively support HEVC, with most major manufacturers announcing support in 2014.[35] Amazon Studios began shooting their full-length original series and new pilots with 4K resolution in 2014.[36]
In March 2016 the first players and disks for Ultra HD Blu-ray—a physical optical disc format supporting 4K resolution and HDR at 60 frames per second—were released.
In 2016 Microsoft released the Xbox One S, a video game console supporting 4K streaming and featuring a Ultra HD Blu-ray disk drive.
