4K Ultra HD

Ultra-high-definition television (also known as Ultra HD television, Ultra HD, UHDTV, UHD and Super Hi-Vision) today includes 4K UHD and 8K UHD, which are two digital video formats with an aspect ratio of 16:9. These were first proposed by NHK Science & Technology Research Laboratories and later defined and approved by the International Telecommunication Union (ITU).

The Consumer Electronics Association announced on October 17, 2012, that "Ultra High Definition", or "Ultra HD", would be used for displays that have an aspect ratio of 16:9 or wider and at least one digital input capable of carrying and presenting native video at a minimum resolution of . In 2015, the Ultra HD Forum was created to bring together the end-to-end video production ecosystem to ensure interoperability and produce industry guidelines so that adoption of ultra-high-definition television could accelerate. From just 30 in Q3 2015, the forum published a list up to 55 commercial services available around the world offering 4K resolution.

The "UHD Alliance", an industry consortium of content creators, distributors, and hardware manufacturers, announced during a Consumer Electronics Show (CES) 2016 press conference its "Ultra HD Premium" specification, which defines resolution, bit depth, color gamut, high dynamic range (HDR) performance required for Ultra HD (UHDTV) content and displays to carry their Ultra HD Premium logo.

Alternative terms

Ultra-high-definition television is also known as Ultra HD, UHD, UHDTV and 4K. In Japan, 8K UHDTV will be known as Super Hi-Vision since Hi-Vision was the term used in Japan for HDTV. In the consumer electronics market companies had previously only used the term 4K at the 2012 CES but that had changed to "Ultra HD" during CES 2013. "Ultra HD" was selected by the Consumer Electronics Association after extensive consumer research, as the term has also been established with the introduction of "Ultra HD Blu-ray".

Technical details

Resolution

Two resolutions are defined as UHDTV:

* UHDTV-1 is 3840 pixels wide by 2160 pixels tall (8.3 megapixels), which is four times as many pixels as the (2.07 megapixels) of current 1080p HDTV (full HDTV).
** Also known as 2160p, and ''4K UHD''. Although roughly similar in resolution to 4K digital cinema formats, it should not be confused with other 4K resolutions such as the ''DCI 4K''/''Cinema 4K''. The total number of pixels of RGB stripe type is 8.3 mega pixel.
* UHDTV-2 is 7680 pixels wide by 4320 pixels tall (33.18 megapixels), also referred to as 4320p and ''8K UHD'', which is sixteen times as many pixels as current 1080p HDTV, which brings it closer to the detail level of 15/70 mm IMAX. NHK advertises the 8K UHDTV format with 22.2 surround sound as ''Super Hi-Vision''.

Color space, dynamic range, frame rate and resolution/aliasing

The human visual system has a limited ability to discern improvements in resolution when picture elements are already small enough or distant enough from the viewer. At some home viewing distances and current TV sizes, HD resolution is near the limits of resolution for the eye and increasing resolution to 4K has little perceptual impact, if consumers are beyond the critical distance (Lechner distance) to appreciate the differences in pixel count between 4K and HD. One exception is that even if resolution surpasses the resolving ability of the human eye, there is still an improvement in the way the image appears due to higher resolutions reducing spatial aliasing.

UHDTV provides other image enhancements in addition to pixel density. Specifically, dynamic range and color are greatly enhanced, and these impact saturation and contrast differences that are readily resolved greatly improve the experience of 4KTV compared to HDTV. UHDTV allows the future use of the new Rec. 2020 (UHDTV) color space which can reproduce colors that cannot be shown with the current Rec. 709 (HDTV) color space.

In terms of CIE 1931 color space, the Rec. 2020 color space covers 75.8%, compared to coverage by the DCI-P3 digital cinema reference projector color space of just 53.6%, 52.1% by Adobe RGB color space, while the Rec. 709 color space covers only 35.9%. UHDTV's increases in dynamic range allow not only brighter highlights but also increased detail in the greyscale. UHDTV also allows for frame rates up to 120 frames per second (fps).

UHDTV potentially allows Rec. 2020, higher dynamic range, and higher frame rates to work on HD services without increasing resolution to 4K, providing improved quality without as high of an increase in bandwidth demand.

History

2001–2005

The first displays capable of displaying 4K content appeared in 2001, as the IBM T220/T221 LCD monitors.

NHK researchers built a UHDTV prototype which they demonstrated in 2003. They used an array of 16 HDTV recorders with a total capacity of almost 3.5 TB that could capture up to 18 minutes of test footage. The camera itself was built with four CCDs, each with a resolution of only . Using two CCDs for green and one each for red and blue, they then used a spatial pixel offset method to bring it to . Subsequently, an improved and more compact system was built using CMOS image sensor technology and the CMOS image sensor system was demonstrated at Expo 2005, Aichi, Japan, the NAB 2006 and NAB 2007 conferences, Las Vegas, at IBC 2006 and IBC 2008, Amsterdam, Netherlands, and CES 2009. A review of the NAB 2006 demo was published in a broadcast engineering e-newsletter. Individuals at NHK and elsewhere projected that the timeframe for UHDTV to be available in domestic homes varied between 2015 and 2020 but Japan was to get it in the 2016 time frame.

2006–2010

On November 2, 2006, NHK demonstrated a live relay of a UHDTV program over a 260 kilometer distance by a fiber-optic network. Using dense wavelength division multiplex (DWDM), 24Gbit/s speed was achieved with a total of 16 different wavelength signals.

On December 31, 2006, NHK demonstrated a live relay of their annual Kōhaku Uta Gassen over IP from Tokyo to a screen in Osaka. Using a codec developed by NHK, the video was compressed from 24Gbit/s to 180600Mbit/s and the audio was compressed from 28Mbit/s to 728Mbit/s. Uncompressed, a 20-minute broadcast would require roughly 4  TB of storage.

The SMPTE first released Standard 2036 for UHDTV in 2007. UHDTV was defined as having two levels, called UHDTV1 () and UHDTV2 ().

In May 2007, the NHK did an indoor demonstration at the NHK Open House in which a UHDTV signal ( at 60fps) was compressed to a 250Mbit/s MPEG2 stream. The signal was input to a 300MHz wide band modulator and broadcast using a 500MHz QPSK modulation. This "on the air" transmission had a very limited range (less than 2 meters), but shows the feasibility of a satellite transmission in the 36,000km orbit.

In 2008, Aptina Imaging announced the introduction of a new CMOS image sensor specifically designed for the NHK UHDTV project. During IBC 2008 Japan's NHK, Italy's RAI, BSkyB, Sony, Samsung, Panasonic Corporation, Sharp Corporation, and Toshiba (with various partners) demonstrated the first ever public live transmission of UHDTV, from London to the conference site in Amsterdam.

On June 9, 2010, Panasonic announced that its professional plasma display lineup would include an plasma display with 4K resolution. At the time of announcement, it was the largest 4K display and the largest television.

On September 29, 2010, the NHK partnered up and recorded The Charlatans live in the UK in the UHDTV format, before broadcasting over the internet to Japan.

2011

On May 19, 2011, Sharp in collaboration with NHK demonstrated a direct-view LCD display capable of pixels at 10 bits per channel. It was the first direct-view Super Hi-Vision-compatible display released.

Before 2011, UHDTV allowed for frame rates of 24, 25, 50, and 60fps. In an ITU-R meeting during 2011, an additional frame rate was added to UHDTV of 120fps.

2012

On February 23, 2012, NHK announced that with Shizuoka University they had developed an 8K sensor that can shoot video at 120fps.

In April 2012, Panasonic, in collaboration with NHK announced a display ( at 60fps), which has 33.2 million 0.417mm square pixels.

In April 2012, the four major South Korean terrestrial broadcasters ( KBS, MBC, SBS, and EBS) announced that in the future, they would begin test broadcasts of UHDTV on channel 66 in Seoul. At the time of the announcement, the UHDTV technical details had not yet been decided. LG Electronics and Samsung are also involved in UHDTV test broadcasts.

In May 2012, NHK showed the world's first ultra-high-definition shoulder-mount camera. By reducing the size and weight of the camera, the portability had been improved, making it more maneuverable than previous prototypes, so it could be used in a wide variety of shooting situations. The single-chip sensor uses a Bayer color-filter array, where only one color component is acquired per pixel. Researchers at NHK also developed a high-quality up-converter, which estimates the other two color components to convert the output into full resolution video.

Also in May 2012, NHK showed the ultra-high-definition imaging system it has developed in conjunction with Shizuoka University, which outputs 33.2-megapixel video at 120fps with a color depth of 12bits per component. As ultra-high-definition broadcasts at full resolution are designed for large, wall-sized displays, there is a possibility that fast-moving subjects may not be clear when shot at 60fps, so the option of 120fps has been standardized for these situations. To handle the sensor output of approximately 4 billion pixels per second with a data rate as high as 51.2Gbit/s, a faster analog-to-digital converter has been developed to process the data from the pixels, and then a high-speed output circuit distributes the resulting digital signals into 96 parallel channels. This CMOS sensor is smaller and uses less power when compared to conventional ultra-high-definition sensors, and it is also the world's first to support the full specifications of the ultra-high-definition standard.

During the 2012 Summer Olympics in Great Britain, the format was publicly showcased by the world's largest broadcaster, the BBC
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