ITU-R Recommendation BT.2020, more commonly known by the abbreviations Rec. 2020 or BT.2020, defines various aspects of

ultra-high-definition television 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 b ...

(UHDTV) with standard dynamic range (SDR) and

wide color gamut In color reproduction, including computer graphics and photography, the gamut, or color gamut , is a certain ''complete subset'' of colors. The most common usage refers to the subset of colors which can be accurately represented in a given cir ...

(WCG), including

picture resolution Image resolution is the detail an image holds. The term applies to digital images, film images, and other types of images. "Higher resolution" means more image detail. Image resolution can be measured in various ways. Resolution quantifies how ...

s, frame rates with progressive scan, bit depths, color primaries,

RGB The RGB color model is an additive color model in which the red, green and blue primary colors of light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three addi ...

and luma-chroma color representations,

chroma subsampling Chroma subsampling is the practice of encoding images by implementing less resolution for chroma information than for luma information, taking advantage of the human visual system's lower acuity for color differences than for luminance. It is u ...

s, and an opto-electronic transfer function. The first version of Rec. 2020 was posted on the

International Telecommunication Union The International Telecommunication Union is a specialized agency of the United Nations responsible for many matters related to information and communication technologies. It was established on 17 May 1865 as the International Telegraph Unio ...

(ITU) website on August 23, 2012, and two further editions have been published since then. Rec. 2020 is extended for high-dynamic-range (HDR) by Rec. 2100, which uses the same color primaries as Rec. 2020.

Technical details

Resolution

Rec. 2020 defines two standard image formats of 3840 × 2160 ("4K") and 7680 × 4320 ("8K"). These both have an aspect ratio of 16:9 and use square

pixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the ...

Frame rate

Rec. 2020 specifies the following frame rates: 120p, 119.88p, 100p, 60p, 59.94p, 50p, 30p, 29.97p, 25p, 24p, 23.976p. Only progressive scan frame rates are allowed.

Digital representation

Rec. 2020 defines a bit depth of either 10 bits per sample or 12 bits per sample. 10 bits per sample Rec. 2020 uses video levels where the

black level Video black level is defined as the level of brightness at the darkest (black) part of a visual image or the level of brightness at which no light is emitted from a screen, resulting in a pure black screen. Video displays generally need to be cal ...

is defined as code 64 and the nominal peak is defined as code 940. Codes 0–3 and 1,020–1,023 are used for the timing reference. Codes 4 through 63 provide video data below the black level while codes 941 through 1,019 provide video data above the nominal peak. 12 bits per sample Rec. 2020 uses video levels where the black level is defined as code 256 and the nominal peak is defined as code 3760. Codes 0–15 and 4,080–4,095 are used for the timing reference. Codes 16 through 255 provide video data below the black level while codes 3,761 through 4,079 provide video data above the nominal peak.

System colorimetry

CIE1931xy gamut comparison of sRGB P3 Rec2020

The Rec. 2020 (UHDTV/UHD-1/UHD-2) color space can reproduce colors that cannot be shown with the Rec. 709 (HDTV) color space. The RGB primaries used by Rec. 2020 are equivalent to monochromatic light sources on the CIE 1931 spectral locus. The

wavelength In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, t ...

of the Rec. 2020

primary color A set of primary colors or primary colours (see spelling differences) consists of colorants or colored lights that can be mixed in varying amounts to produce a gamut of colors. This is the essential method used to create the perception of a ...

s is 630 nm for the red primary color, 532 nm for the green primary color, and 467 nm for the blue primary color. In coverage of the

CIE 1931 color space The CIE 1931 color spaces are the first defined quantitative links between distributions of wavelengths in the electromagnetic visible spectrum, and physiologically perceived colors in human color vision. The mathematical relationships that defin ...

, the Rec. 2020 color space covers 75.8%, the

DCI-P3 P3 is an RGB color space. DCI-P3 (Digital Cinema Initiative) is used with digital theatrical motion picture distribution (DCDM). Display P3 is a variant developed by Apple Inc. for wide-gamut displays. __TOC__ History Development of the sta ...

digital cinema color space covers 53.6%, the

Adobe RGB color space The Adobe RGB (1998) color space or opRGB is a color space developed by Adobe Systems, Inc. in 1998. It was designed to encompass most of the colors achievable on CMYK color printers, but by using RGB primary colors on a device such as a compu ...

covers 52.1%, and the Rec. 709 color space covers 35.9%. During the development of the Rec. 2020 color space it was decided that it would use real colors, instead of imaginary colors, so that it would be possible to show the Rec. 2020 color space on a display without the need for conversion circuitry. Since a larger color space increases the difference between colors, an increase of 1 bit per sample is needed for Rec. 2020 to equal or exceed the color precision of Rec. 709. The

NHK , also known as NHK, is a Japanese public broadcaster. NHK, which has always been known by this romanized initialism in Japanese, is a statutory corporation funded by viewers' payments of a television license fee. NHK operates two terrestr ...

measured

contrast sensitivity Contrast is the contradiction in luminance or colour that makes an object (or its representation in an image or display) distinguishable. In visual perception of the real world, contrast is determined by the difference in the colour and bright ...

for the Rec. 2020 color space using Barten's equation which had previously been used to determine the bit depth for digital cinema. 11 bits per sample for the Rec. 2020 color space is below the visual modulation threshold, the ability to discern a one-value difference in luminance, for the entire luminance range. The NHK is planning for their UHDTV system, Super Hi-Vision, to use 12 bits per sample

Transfer characteristics

Rec. 2020 defines a

nonlinear In mathematics and science, a nonlinear system is a system in which the change of the output is not proportional to the change of the input. Nonlinear problems are of interest to engineers, biologists, physicists, mathematicians, and many othe ...

transfer function In engineering, a transfer function (also known as system function or network function) of a system, sub-system, or component is a mathematical function that theoretically models the system's output for each possible input. They are widely used ...

for

gamma correction Gamma correction or gamma is a nonlinear operation used to encode and decode luminance or tristimulus values in video or still image systems. Gamma correction is, in the simplest cases, defined by the following power-law expression: : V_\tex ...

that is the same nonlinear transfer function that is used by Rec. 709, except that its parameters are (for 12 bit only) given with higher precision:

E^\prime=\begin
4.5E & 0 \le E < \beta\,\!\\
\alpha\,\!E^ - (\alpha\,\! - 1) & \beta\,\! \le E \le 1
\end

*where ''E'' is the signal proportional to camera-input light intensity and ''E′'' is the corresponding nonlinear signal *where ''α'' = 1 + 5.5 * ''β'' ≈ 1.09929682680944 and ''β'' ≈ 0.018053968510807 (values chosen to achieve a continuous function with a continuous first derivative) The standard says that for practical purposes, the following values of ''α'' and ''β'' can be used: * ''α'' = 1.099 and ''β'' = 0.018 for 10 bits per sample system (the values given in Rec. 709) * ''α ''= 1.0993 and ''β'' = 0.0181 for 12 bits per sample system While the Rec. 2020 transfer function can be used for encoding, it is expected that most productions will use a reference monitor that has an appearance of using equivalent of gamma 2.4 transfer function as defined in ITU-R BT.1886 and that the reference monitor will be evaluated under viewing conditions as defined in Rec. ITU-R BT.2035.

RGB and luma-chroma formats

Rec. 2020 allows for

and luma-chroma signal formats with 4:4:4 full-resolution sampling and luma-chroma signal formats with 4:2:2 and 4:2:0

. It supports two types of luma-chroma signals, called

YCbCr YCbCr, Y′CbCr, or Y Pb/Cb Pr/Cr, also written as YCBCR or Y′CBCR, is a family of color spaces used as a part of the color image pipeline in video and digital photography systems. Y′ is the luma component and CB and CR are the blue-diff ...

and YcCbcCrc. YCbCr may be used when the top priority is compatibility with existing

SDTV Standard-definition television (SDTV, SD, often shortened to standard definition) is a television system which uses a resolution that is not considered to be either high or enhanced definition. "Standard" refers to it being the prevailing sp ...

and

HDTV High-definition television (HD or HDTV) describes a television system which provides a substantially higher image resolution than the previous generation of technologies. The term has been used since 1936; in more recent times, it refers to the g ...

operating practices. The

luma Luma or LUMA may refer to: Arts * La Trobe University Museum of Art, Melbourne, Australia * LUMA Projection Arts Festival, an annual event featuring building-scale projection mapping and light installations in Binghamton, NY * LUMA Foundation, ...

(Y′) signal for YCbCr is calculated as the

weighted average The weighted arithmetic mean is similar to an ordinary arithmetic mean (the most common type of average), except that instead of each of the data points contributing equally to the final average, some data points contribute more than others. The ...

Y′ = K_R⋅R′ + K_G⋅G′ + K_B⋅B′, using the gamma-corrected RGB values (denoted R′G′B′) and the weighting coefficients K_R = 0.2627, K_G = 1−K_R−K_B = 0.678 and K_B = 0.0593. As in similar schemes, the chroma components in YCbCr are calculated as C′_B = 0.5⋅(B′−Y′)/(1−K_B) = (B'−Y′)/1.8814 and C′_R = 0.5⋅(R′−Y′)/(1−K_R) = (R′−Y′)/1.4746, and for digital representation the Y′, C′_B, and C′_R signals are scaled, offset by constants, and rounded to integers. The YcCbcCrc scheme is a "constant luminance" luma-chroma representation. YcCbcCrc may be used when the top priority is the most accurate retention of luminance information. The luma component in YcCbcCrc is calculated using the same coefficient values as for YCbCr, but it is calculated from linear RGB and then gamma corrected, rather than being calculated from gamma-corrected R′G′B′ and is done as follows: Y′ = (K_R⋅R + K_G⋅G + K_B⋅B)′. The chroma components in YcCbcCrc are calculated from the Y′, B′, and R′ signals with equations that depend on the range of values of B′−Y′ and R′−Y′.

Color management

Just like standard definition content, that uses SMPTE C or NTSC 1953, BT.2020 primaries should be color managed to primaries of display. That is different from changing YCbCr matrix. HD content is color managed to BT.709 primaries on linear values. BT.2020 and BT.2100 are usually color managed to P3-D65. The reference color bars for BT.2020 are

ARIB The , commonly known as , is a standardization organization in Japan. ARIB is designated as the center of promotion of the efficient use of the radio spectrum and designated frequency change support agency. Its activities include those previously ...

STD-B66.

Implementations

HDMI 2.0 supports the Rec. 2020 color space. HDMI 2.0 can transmit 12 bits per sample RGB at a resolution of 2160p and a frame rate of 24/25/30 fps or it can transmit 12 bits per sample 4:2:2/4:2:0 YCbCr at a resolution of 2160p and a frame rate of 50/60 fps. The Rec. 2020 color space is supported by H.264/MPEG-4 AVC and H.265/

High Efficiency Video Coding High Efficiency Video Coding (HEVC), also known as H.265 and MPEG-H Part 2, is a video coding format, video compression standard designed as part of the MPEG-H project as a successor to the widely used Advanced Video Coding (AVC, H.264, or MPEG-4 ...

(HEVC). The Main 10 profile in HEVC was added based on proposal JCTVC-K0109 which proposed that a 10-bit profile be added to HEVC for consumer applications. The proposal stated that this was to allow for improved video quality and to support the Rec. 2020 color space that will be used by UHDTV. On September 11, 2013, ViXS Systems announced the XCode 6400 SoC which supports 4K resolution at 60 fps, the Main 10 profile of HEVC, and the Rec. 2020 color space.

2014

On May 22, 2014,

Nanosys Nanosys is a nanotechnology company located in Milpitas, California and founded in 2001. The company develops and manufactures quantum dot materials for display products. Products Quantum Dot Enhancement Film (QDEF) Nanosys Quantum Dot Enhance ...

announced that using a quantum dot enhancement film (QDEF) a current LCD TV was modified so that it could cover 91% of the Rec. 2020 color space. Nanosys engineers believe that with improved LCD color filters it is possible to make a LCD that covers 97% of the Rec. 2020 color space. On September 4, 2014,

Canon Inc. is a Japanese multinational corporation headquartered in Ōta, Tokyo, Japan, specializing in optical, imaging, and industrial products, such as lenses, cameras, medical equipment, scanners, printers, and semiconductor manufacturing equipment.< ...

released a firmware upgrade, that added support for the Rec. 2020 color space, to their EOS C500 and EOS C500 PL camera models and their DP-V3010 4K display. On September 5, 2014, the Blu-ray Disc Association revealed that the future 4K Blu-ray Disc format will support 4K UHD (3840x2160 resolution) video at frame rates up to 60 frames per second. The standard will encode videos under the

standard. 4K Blu-ray Discs support both a higher color precision by increasing the color depth to 10 bits per color, and a greater color gamut by using the Rec. 2020 color space. The 4K-Blu-ray specification allows for three disc sizes, each with their own data rate: 50 GB with 82 Mbit/s, 66 GB with 108 Mbit/s, and 100 GB with 128 Mbit/s. The first

Ultra HD Blu-ray Ultra HD Blu-ray (4K Ultra HD, UHD-BD, or 4K Blu-ray) is a digital optical disc data storage format that is an enhanced variant of Blu-ray. Ultra HD Blu-ray discs are incompatible with existing standard Blu-ray players, though a traditional Bl ...

titles were officially released from four studios on March 1, 2016. On November 6, 2014,

Google Google LLC () is an American Multinational corporation, multinational technology company focusing on Search Engine, search engine technology, online advertising, cloud computing, software, computer software, quantum computing, e-commerce, ar ...

added support for the Rec. 2020 color space to VP9. On November 7, 2014, DivX developers announced that DivX265 version 1.4.21 has added support for the Main 10 profile of HEVC and the Rec. 2020 color space. On December 22, 2014,

Avid Technology Avid Technology is an American technology and multimedia company based in Burlington, Massachusetts, and founded in August 1987 by Bill Warner. It specialises in audio and video; specifically, digital non-linear editing (NLE) systems, video edi ...

released an update for

Media Composer Avid Media Composer is a film and video editing software application or non-linear editing system (NLE) developed by Avid Technology. Initially released in 1989 on Macintosh II as an offline editing system, the application has since evolved to ...

that added support for 4K resolution, the Rec. 2020 color space, and a bit rate of up to 3,730 Mbit/s with the

DNxHD codec Avid DNxHD ("Digital Nonlinear Extensible High Definition") is a lossy high-definition video post-production codec developed by Avid for multi-generation compositing with reduced storage and bandwidth requirements. It is an implementation of SMPTE ...

2015

On January 6, 2015, the MHL Consortium announced the release of the superMHL specification which will support 8K resolution at 120 fps, 48-bit video, the Rec. 2020 color space, high dynamic range support, a 32-pin reversible superMHL connector, and power charging of up to 40 watts. On January 7, 2015,

Ateme Ateme S.A. is a multinational company that specializes in video delivery, namely software for video compression based on High_Efficiency_Video_Coding, H.265 / High_Efficiency_Video_Coding, HEVC standards; MPEG4; MPEG2 Data_compression#Video, encod ...

added support for the Rec. 2020 color space to their TITAN File video platform. On March 18, 2015, Arri announced the SXT line of

Arri Alexa The Arri Alexa (stylised as ΛLEXΛ) is a digital motion picture camera system developed by Arri. First introduced in April 2010, the camera was Arri's first major transition into digital cinematography after previous efforts such as the Arrif ...

cameras which will support Apple ProRes recording at 4K resolution and the Rec. 2020 color space. On April 8, 2015, Canon Inc. announced the DP-V2410 4K display and EOS C300 Mark II camera with support for the Rec. 2020 color space. On May 26, 2015, the NHK announced a 4K LCD with a

laser diode The laser diode chip removed and placed on the eye of a needle for scale A laser diode (LD, also injection laser diode or ILD, or diode laser) is a semiconductor device similar to a light-emitting diode in which a diode pumped directly with e ...

backlight that covers 98% of the Rec. 2020 color space. Using a laser allows for generating almost monochromatic light. The NHK stated that at the time it was announced this 4K LCD has the widest color gamut of any display in the world. On June 17, 2015, Digital Projection International presented a 4K LED projector with support for the Rec. 2020 color space.

2016

On January 4, 2016, the UHD Alliance announced their specifications for Ultra HD Premium which includes support for the Rec. 2020 color space. On January 27, 2016, VESA announced that

DisplayPort DisplayPort (DP) is a digital display interface developed by a consortium of PC and chip manufacturers and standardized by the Video Electronics Standards Association (VESA). It is primarily used to connect a video source to a display device su ...

version 1.4 will support the Rec. 2020 color space. On April 17, 2016,

Sony , commonly stylized as SONY, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. As a major technology company, it operates as one of the world's largest manufacturers of consumer and professiona ...

presented a 4K

OLED An organic light-emitting diode (OLED or organic LED), also known as organic electroluminescent (organic EL) diode, is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compound that emits light i ...

display with the support of Rec. 2020 color space. On April 18, 2016, the Ultra HD Forum announced industry guidelines for UHD Phase A which includes support for the Rec. 2020 color space.

2017

At SID display week 2017, AUO displayed a 5" foldable 720p HD AMOLED display able to display 95% of the Rec. 2020 colorspace. Although 720p is not specified by Rec. 2020, the color space coverage is of note. The Ultra HD Forum guidelines for UHD Phase A include support for SDR formats with 10 bits of color bit depth based on both Rec. 709 and Rec. 2020 color gamuts and also both the HDR10 and HLG formats of Rec. 2100, which are supposed to start by 2017.

2018

At SID display week 2018, various companies showcased displays that are able to cover over 90% of the Rec.2020 color space. JDI showcased an improvement of their 17.3" LCD 8k broadcast monitor that is powered by an RGB laser backlight system. This allows the display to reproduce 97% of the Rec. 2020 color space.

Rec. 2100

Rec. 2100 is an ITU-R Recommendation released in July 2016 that defines

high dynamic range High dynamic range (HDR) is a dynamic range higher than usual, synonyms are wide dynamic range, extended dynamic range, expanded dynamic range. The term is often used in discussing the dynamic range of various signals such as images, videos, au ...

(HDR) formats for both HDTV 1080p and 4K/8K UHDTV resolutions. These formats use the same color primaries as Rec. 2020, but with different transfer functions for HDR use. Rec. 2100 does not support the YcCbcCrc scheme of Rec. 2020.

References

External links

ITU-R Recommendation BT.2020
{{Color space Color space Film and video technology ITU-R recommendations Telecommunications-related introductions in 2012 Audiovisual introductions in 2012 Television transmission standards Ultra-high-definition television