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Rec. 2020
View on Wikipedia| Rec. 2020 | |
|---|---|
 CIE 1931 chromaticity diagram showing the Rec. 2020 (UHDTV) color space in the triangle and the location of the primary colors. Rec. 2020 uses Illuminant D65 for the white point. | |
| Status | Approved |
| First published | August 23, 2012[1] |
| Latest version | BT.2020-2 October 14, 2015[2] |
| Authors | ITU-R |
| Base standards | Rec. 2020, BT.2020 |
| Domain | Digital image processing |
| Website | www |
ITU-R Recommendation BT.2020, more commonly known by the abbreviations Rec. 2020 or BT.2020, defines various aspects of ultra-high-definition television (UHDTV) with standard dynamic range (SDR) and wide color gamut (WCG), including picture resolutions, frame rates with progressive scan, bit depths, color primaries, RGB and luma-chroma color representations, chroma subsamplings, and an opto-electronic transfer function.[2] The first version of Rec. 2020 was posted on the International Telecommunication Union (ITU) website on August 23, 2012, and two further editions have been published since then.[2][1][3][4][5]
Rec. 2020 is extended for high-dynamic-range (HDR) by Rec. 2100, which uses the same color primaries as Rec. 2020.
Technical details
[edit]Resolution
[edit]Rec. 2020 defines two standard image formats of 3840 × 2160 ("4K") and 7680 × 4320 ("8K").[2] These both have an aspect ratio of 16:9 and use square pixels.[2]
Frame rate
[edit]Rec. 2020 specifies the following frame rates: 120p, 119.88p, 100p, 60p, 59.94p, 50p, 30p, 29.97p, 25p, 24p, 23.976p.[2] Only progressive scan frame rates are allowed.[2]
Digital representation
[edit]Rec. 2020 defines a bit depth of either 10 bits per sample or 12 bits per sample.[2]
10 bits per sample Rec. 2020 uses video levels where the black level 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.[2]
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.[2]
System colorimetry
[edit]| Color space | White point | Primaries | ||||||
|---|---|---|---|---|---|---|---|---|
| xW | yW | xR | yR | xG | yG | xB | yB | |
| ITU-R BT.2020 | 0.3127 | 0.3290 | 0.708 | 0.292 | 0.170 | 0.797 | 0.131 | 0.046 |
The Rec. 2020 (UHDTV/UHD-1/UHD-2) color space can reproduce colors that cannot be shown with the Rec. 709 (HDTV) color space.[6][7] The RGB primaries used by Rec. 2020 are equivalent to monochromatic light sources on the CIE 1931 spectral locus.[7][8][9] The wavelength of the Rec. 2020 primary colors is 630 nm for the red primary color, 532 nm for the green primary color, and 467 nm for the blue primary color.[8][10][11] In coverage of the CIE 1931 color space, the Rec. 2020 color space covers 75.8%, the DCI-P3 digital cinema color space covers 53.6%, the Adobe RGB color space covers 52.1%, and the Rec. 709 color space covers 35.9%.[6]
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.[12] 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.[12]
The NHK measured contrast sensitivity for the Rec. 2020 color space using Barten's equation which had previously been used to determine the bit depth for digital cinema.[13][6] 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.[6] The NHK is planning for their UHDTV system, Super Hi-Vision, to use 12 bits per sample RGB.[6][14]
Transfer characteristics
[edit]Rec. 2020 defines a nonlinear transfer function for gamma correction 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:[2][15]
- 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.[2][16][17]
RGB and luma-chroma formats
[edit]Rec. 2020 allows for RGB 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 chroma subsampling.[2] It supports two types of luma-chroma signals, called YCbCr and YcCbcCrc.
YCbCr may be used when the top priority is compatibility with existing SDTV and HDTV operating practices.[2][12] The luma (Y′) signal for YCbCr is calculated as the weighted average Y′ = KR⋅R′ + KG⋅G′ + KB⋅B′, using the gamma-corrected RGB values (denoted R′G′B′) and the weighting coefficients KR = 0.2627, KG = 1−KR−KB = 0.678, and KB = 0.0593.[2] As in similar schemes, the chroma components in YCbCr are calculated as C′B = 0.5⋅(B′−Y′)/(1−KB) = (B'−Y′)/1.8814 and C′R = 0.5⋅(R′−Y′)/(1−KR) = (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.[2] YcCbcCrc may be used when the top priority is the most accurate retention of luminance information.[2] 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′ = (KR⋅R + KG⋅G + KB⋅B)′.[12] 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
[edit]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.[18][19][20] The reference color bars for BT.2020 are ARIB STD-B66.[21]
Implementations
[edit]The Rec. 2020 color space is supported by H.264/MPEG-4 AVC and H.265/High Efficiency Video Coding (HEVC).[22][23][24] 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.[25] 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.[25]
2013
[edit]On September 4, 2013, The HDMI forum announced version 2.0 of the HDMI specification (also known as HDMI 2.0), which supports the Rec. 2020 color space.[26]
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.[27]
2014
[edit]On May 22, 2014, Nanosys 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.[28] 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.[28]
On September 4, 2014, Canon Inc. 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.[29][30]
On September 5, 2014, the Blu-ray Disc Association revealed that the future 4K Blu-ray Disc format will support 4K UHD (3840 x 2160 resolution) video at frame rates up to 60 fps.[31] The standard will encode videos under the High Efficiency Video Coding standard.[31] 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.[31] The 4K Blu-ray specification allows for three disc sizes: 50 gb, 66 gb and 100 gb. Depending on the disc size and physical configuration, the data rate can reach up to 128 Mbit/s.[31] The first Ultra HD Blu-ray titles were officially released from four studios on March 1, 2016.[32]
On November 6, 2014, Google added support for the Rec. 2020 color space to VP9.[33]
On November 7, 2014, DivX developers announced that DivX265 version 1.4.21 had added support for the Main 10 profile of HEVC and the Rec. 2020 color space.[34]
On December 22, 2014, Avid Technology released an update for Media Composer 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.[35][36]
2015
[edit]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.[37][38][39]
On January 7, 2015, Ateme added support for the Rec. 2020 color space to their TITAN File video platform.[40]
On March 18, 2015, Arri announced the SXT line of Arri Alexa cameras which will support Apple ProRes recording at 4K resolution and the Rec. 2020 color space.[41][42]
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.[43][44]
On May 26, 2015, the NHK announced a 4K LCD with a laser diode backlight that covers 98% of the Rec. 2020 color space. Using a laser allows for generating almost monochromatic light.[45][46] The NHK stated that at the time it was announced this 4K LCD has the widest color gamut of any display in the world.[47]
On June 17, 2015, Digital Projection International presented a 4K LED projector with support for the Rec. 2020 color space.[48]
2016
[edit]On January 4, 2016, the UHD Alliance announced their specifications for Ultra HD Premium which includes support for the Rec. 2020 color space.[49]
On January 27, 2016, VESA announced that DisplayPort version 1.4 will support the Rec. 2020 color space.[50]
On April 17, 2016, Sony presented a 55 in (140 cm) 4K OLED display with the support of Rec. 2020 color space.[51]
On April 18, 2016, the Ultra HD Forum announced industry guidelines for UHD Phase A which includes support for the Rec. 2020 color space.[52][53]
2017
[edit]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.[52]
2018
[edit]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.
Web browsers
[edit]Rec. 2020 colors are supported in CSS Color Level 4 on Safari since 2022 (version 15.1) and Google Chrome since 2023 (version 111) browsers.[54][55]
| sRGB | Rec. 2020 | |
|---|---|---|
| Red | ||
| Green | ||
| Blue |
Rec. 2100
[edit]Rec. 2100 is an ITU-R Recommendation released in July 2016 that defines high dynamic range (HDR) formats for both HDTV 1080p and 4K/8K UHDTV resolutions.[56] 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.
See also
[edit]References
[edit]- ^ a b "BT.2020: Parameter values for ultra-high definition television systems for production and international programme exchange". International Telecommunication Union. 2012-08-23. Retrieved 2014-08-31.
- ^ a b c d e f g h i j k l m n o p q r "BT.2020: Parameter values for ultra-high definition television systems for production and international programme exchange". International Telecommunication Union. 2014-07-17. Retrieved 2014-08-31.
- ^ "The international standard for Super Hi-Vision TV". NHK. 2012-08-23. Retrieved 2012-08-30.
- ^ "8K Ultra High Def TV Format Opens Options for TV Viewing". The Hollywood Reporter. 2012-08-28. Retrieved 2012-08-30.
- ^ "ITU approves NHK's Super Hi-Vision as 8K standard, sets the UHDTV ball rolling very slowly". Engadget. 2012-08-25. Retrieved 2012-08-30.
- ^ a b c d e ""Super Hi-Vision" as Next-Generation Television and Its Video Parameters". Information Display. Archived from the original on 2013-06-15. Retrieved 2012-12-27.
- ^ a b "Super Hi-Vision format". NHK. Archived from the original on 2012-08-13. Retrieved 2012-08-24.
- ^ a b "Wide-color-gamut Super Hi-Vision System". NHK. Archived from the original on 2014-01-08. Retrieved 2013-05-18.
- ^ "The present state of ultra-high definition television" (PDF). ITU-R. Archived from the original (PDF) on 2 December 2021. Retrieved 2 December 2021.
- ^ "The Pointer's Gamut - The Coverage of Real Surface Colors by RGB Color Spaces and Wide Gamut Displays". TFTCentral. 19 February 2014. Archived from the original on 31 August 2021. Retrieved 31 August 2021.
- ^ David Wood (2012-03-08). "Deciding Tomorrow's Television Parameters" (PDF). European Broadcasting Union. Archived from the original (PDF) on 2014-01-08. Retrieved 2013-05-02.
- ^ a b c d "BT.2246-2(2012): The present state of ultra-high definition television". International Telecommunication Union. 2013-01-16. Retrieved 2013-04-30.
- ^ ""Super Hi-Vision" as Next-Generation Television and Its Video Parameters" (PDF). Society for Information Display. TV Technology Issue. 28 (12): 14. ISSN 0362-0972. Archived (PDF) from the original on 2024-05-17.
- ^ "Super Hi-Vision Production Devices for Mobile". NHK. Archived from the original on 2014-01-08. Retrieved 2013-05-18.
- ^ "BT.709: Parameter values for the HDTV standards for production and international programme exchange". International Telecommunication Union. 2009-08-27. Retrieved 2012-09-15.
- ^ "BT.1886: Reference electro-optical transfer function for flat panel displays used in HDTV studio production". International Telecommunication Union. 2011-04-06. Retrieved 2014-08-31.
- ^ "BT.2035: A reference viewing environment for evaluation of HDTV program material or completed programmes". International Telecommunication Union. 2013-08-13. Retrieved 2014-11-05.
- ^ "Colour gamut conversion from Recommendation ITU-R BT.2020 to Recommendation ITU-R BT.709". ITU. Archived from the original on September 10, 2021. Retrieved 2021-05-01.
- ^ "BT.2087 : Colour conversion from Recommendation ITU-R BT.709 to Recommendation ITU-R BT.2020". www.itu.int. Archived from the original on May 1, 2021. Retrieved 2021-05-01.
- ^ "[407] Proposed addition to Report ITU-R BT.2390 - Recommendation ITU-R BT.2100 signal conversion to and from P3D65 systems". www.itu.int. Archived from the original on May 1, 2021. Retrieved 2021-05-01.
- ^ "About obtaining ARIB Standards (STD-B66)｜Association of Radio Industries and Businesses". www.arib.or.jp. Retrieved 2021-05-01.
- ^ "H.264: Advanced video coding for generic audiovisual services". ITU. 2013-06-07. Retrieved 2013-06-16.
- ^ G.J. Sullivan; J.-R. Ohm; W.-J. Han; T. Wiegand (2012-05-25). "Overview of the High Efficiency Video Coding (HEVC) Standard" (PDF). IEEE Transactions on Circuits and Systems for Video Technology. Retrieved 2013-06-16.
- ^ "H.265: High efficiency video coding". ITU. 2013-06-12. Retrieved 2013-06-16.
- ^ a b Alberto Dueñas; Adam Malamy (2012-10-18). "On a 10-bit consumer-oriented profile in High Efficiency Video Coding (HEVC)". JCT-VC. Archived from the original on 2013-02-13. Retrieved 2013-06-16.
- ^ "HDMI FORUM RELEASES VERSION 2.0 OF THE HDMI SPECIFICATION". HDMI.org. Retrieved 2025-05-27.
- ^ "ViXS Announces XCode 6400, the World's First System-on-Chip (SoC) with Native Support for 10-bit High Efficiency Video Coding (HEVC) and Ultra High Definition (HD) 4K". PRNewswire. 2013-09-11. Retrieved 2013-09-15.
- ^ a b "Is the rec.2020 UHD color broadcast spec really practical?". Nanosys. 2014-05-22. Retrieved 2014-07-21.
- ^ "Free Canon Firmware for Cinema EOS System Cameras Delivers Improved Basic Performance, Including Support for ITU-R BT.2020 Color Space". MarketWatch. September 4, 2014. Retrieved September 6, 2014.
- ^ "Free Canon Firmware Upgrade for DP-V3010 30-Inch 4K Professional Display Enables Confirmation of ITU-R BT.2020 Color Gamut Video Content". Business Wire. September 4, 2014. Retrieved September 6, 2014.
- ^ a b c d "4K Blu-ray discs arriving in 2015 to fight streaming media". CNET. September 5, 2014. Retrieved October 18, 2014.
- ^ "Upcoming Fox 4K Blu-ray Titles". Retrieved January 12, 2016.
- ^ "Change the use of a reserved color space entry". Chromium (web browser). 2014-11-06. Retrieved 2014-11-07.
- ^ "DivX HEVC Community Encoder" (Press release). DivX. 2014-11-04. Retrieved 2014-11-15.
- ^ Wim Van den Broeck (2014-12-22). "Editing 4K and Beyond in Media Composer Now Available with Avid Resolution Independence Update". Avid Technology. Retrieved 2014-12-23.
- ^ Bryant Frazer (2014-12-22). "Starting Today, You Can Finally Edit 4K Natively in the Avid". studiodaily. Retrieved 2014-12-23.
- ^ "MHL Consortium Announces superMHL – the First Audio/Video Specification With Support Up to 8K". Yahoo Finance. 2015-01-06. Archived from the original on 2015-10-20. Retrieved 2015-01-10.
- ^ Ryan Smith (2015-01-06). "MHL Consortium Announces superMHL: New Standard & New Cable To Drive 8K TV". AnandTech. Archived from the original on January 7, 2015. Retrieved 2015-01-10.
- ^ "Introducing superMHL". MHL. Retrieved 2015-01-10.
- ^ "High Fidelity Pixels Enhance Ultra HD Video On Demand". PR Newswire. 2015-01-07. Retrieved 2015-01-10.
- ^ Deborah D. McAdams (2015-03-18). "Arri Rolls Out Alexa With 4K ProRes Recording". TVTechnology. Archived from the original on 2015-03-21. Retrieved 2015-03-19.
- ^ "ALEXA SXT". Arri. Archived from the original on 2015-03-20. Retrieved 2015-03-19.
- ^ Jose Antunes (2015-04-08). "New 24-inch 4K Reference Display from Canon". Pro Video Coalition. Retrieved 2015-04-08.
- ^ Jose Antunes (2015-04-08). "The EOS C300 Mark II Has Arrived". Pro Video Coalition. Retrieved 2015-04-08.
- ^ "NHK Showcases Latest 8K Super Hi-Vision Technologies". cdrinfo. 2015-05-26. Retrieved 2015-05-26.
- ^ "Laser-backlit Wide-gamut LCD and Color Gamut Mapping". NHK. Archived from the original on 2015-05-27. Retrieved 2015-05-26.
- ^ Tetsuo Nozawa (2015-06-01). "STRL Announces 4k Display With World's Widest Color Gamut". Nikkei Business Publications. Retrieved 2015-06-01.
- ^ "Digital Projection Launches World's Brightest LED Projector at InfoComm" (Press release). AVNetwork. June 16, 2015. Retrieved May 8, 2016.
- ^ "UHD Alliance Defines Premium Home Entertainment Experience". Business Wire. 2016-01-04. Retrieved 2016-01-13.
- ^ "VESA Updates Display Stream Compression Standard to Support New Applications and Richer Display Content". PRNewswire. 2016-01-27. Retrieved 2016-01-29.
- ^ "Sony introduces the PVM-X550, a 55" quad-view large screen Trimaster EL 4K OLED monitor" (Press release). Sony. 2016-04-17. Archived from the original on 2016-06-03. Retrieved 2016-05-08.
- ^ a b "End-to-end guidelines for phase A implementation". Ultra HD Forum. 2016-04-18. Retrieved 2016-04-18.
- ^ "Ultra HD Forum Releases First Industry Guidelines for Deploying End-to-End Live & Pre-Recorded UHD Services in 2016". Business Wire. 2016-04-18. Retrieved 2016-04-18.
- ^ "CSS Color Module Level 4". www.w3.org. Archived from the original on 2024-12-30. Retrieved 2025-01-06.
- ^ "CSS color() function". Can I use...
- ^ "BT.2100: Image parameter values for high dynamic range television for use in production and international programme exchange". International Telecommunication Union. 2016-07-04. Retrieved 2016-07-04.
External links
[edit]| CAM | |
|---|---|
| CIE | |
| RGB | |
| Y′UV | |
| Other | |
| Color systems and standards | |
For the vision capacities of organisms or machines, see  Color vision. | |
Rec. 2020
View on GrokipediaOverview
Definition and Scope
Rec. 2020, formally known as Recommendation ITU-R BT.2020, is an international standard developed by the International Telecommunication Union Radiocommunication Sector (ITU-R) that defines parameter values for ultra-high-definition television (UHDTV) systems with standard dynamic range (SDR) and wide color gamut (WCG).[3] Originally published in August 2012, it was revised in October 2015 as BT.2020-2 to incorporate updates on system parameters.[4] The standard specifies image formats, scanning structures, and colorimetry for UHDTV production and international program exchange, aiming to deliver enhanced visual experiences through higher resolution and expanded color reproduction.[3] The scope of Rec. 2020 encompasses UHDTV systems at resolutions of 3840 × 2160 (4K) and 7680 × 4320 (8K), with a 16:9 aspect ratio and progressive scan only, excluding interlaced formats to ensure high-quality motion portrayal.[3] It supports frame rates including 24, 25, 30, 50, 60, 100, and 120 Hz (or their 1.001 equivalents), structured into two tiers: Level 1 for 4K, suitable for consumer and broadcast applications, and Level 2 for 8K, enabling advanced production scenarios, with both levels supporting frame rates up to 120 Hz.[5] Key goals include expanding color reproduction beyond the Rec. 709 standard used in high-definition television (HDTV), approaching the limits of human color perception while maintaining compatibility with existing digital infrastructure for program exchange and broadcasting where feasible.[5] Rec. 2020 serves as the foundational SDR and WCG framework for UHDTV, with extensions for high dynamic range (HDR) defined in Rec. 2100.Historical Development
The development of Rec. 2020, formally known as Recommendation ITU-R BT.2020, began in 2012 within the framework of ITU-R Working Party 6A, which focused on advancing terrestrial broadcasting systems beyond the high-definition television (HDTV) parameters established in Rec. 709.[6] This effort addressed the growing industry demand for ultra-high-definition television (UHDTV) standards to support higher resolutions and wider color gamuts, driven by advancements in digital cinema and broadcast production. The initial parameters, including support for 4K resolution (3840 × 2160 pixels) and a significantly expanded color gamut, were shaped by contributions from broadcasters such as NHK and the European Broadcasting Union (EBU), who advocated for enhanced image quality to meet future content creation needs.[5] BT.2020-0 was approved on August 23, 2012, marking the first formal standardization of UHDTV video parameters for production and international exchange. This version laid the groundwork by specifying key aspects like progressive scan formats and a color space extending beyond Rec. 709 to encompass a broader range of visible colors. The timing aligned with early demonstrations of UHDTV technology, including coverage of the 2012 London Olympics, where prototype systems were tested for live event broadcasting, providing practical insights that informed the standard's evolution.[7][8] Subsequent revisions refined and expanded the standard. BT.2020-1, approved in June 2014, introduced additional details on frame rates, including support for 100 Hz and 120 Hz.[6] BT.2020-2, approved on October 14, 2015, finalized the sampling structures for chroma subsampling and consolidated the core parameters, including those influenced by related high dynamic range (HDR) developments like SMPTE ST 2082, which later informed the HDR extension in BT.2100. No further revisions have occurred as of 2025, with BT.2020-2 remaining the active version managed under ITU-R Study Group 6.[6]Core Technical Parameters
Resolution and Frame Rates
Rec. 2020 defines two levels of ultra-high-definition television (UHDTV) resolutions: level 1 at 3840 × 2160 pixels (approximately 8.3 million pixels) and level 2 at 7680 × 4320 pixels (approximately 33.2 million pixels), both with a 16:9 aspect ratio. Images use progressive scanning with square pixels arranged in a left-to-right, top-to-bottom raster. Supported frame frequencies include 24 Hz, 25 Hz, 30 Hz, 50 Hz, 60 Hz, 100 Hz, and 120 Hz, along with variants divided by 1.001 (e.g., 23.976 Hz, 29.97 Hz, 59.94 Hz) for compatibility with existing NTSC-based systems. These parameters ensure synchronization and interoperability in production and exchange workflows.[9]Digital Representation
Rec. 2020 specifies digital representation parameters for ultra-high-definition television (UHDTV) signals to ensure compatibility in production, exchange, and distribution while supporting wide color gamut content. The standard mandates a minimum bit depth of 10 bits per component (R', G', B', Y', or color-difference signals) for production and international programme exchange, enabling sufficient quantization levels to represent the expanded color volume without perceptible banding in gradients. A 12-bit depth is also permitted for applications requiring enhanced precision, with quantization levels defined such that for 10-bit coding, the black level is 64 and nominal peak is 940 (video range 4 to 1019), while for 12-bit, black is 512 and peak is 3760 (video range 16 to 4079).[9] Chroma subsampling options in Rec. 2020 include 4:4:4 (full resolution for all components), 4:2:2 (horizontal subsampling of chroma by a factor of 2), and 4:2:0 (both horizontal and vertical subsampling of chroma by a factor of 2), all using an orthogonal sampling lattice co-sited with luma samples for compatibility with existing infrastructure. Among these, 4:2:0 is recommended for broadcast transmission due to its efficiency in reducing data rates for compression codecs like HEVC, thereby minimizing bandwidth requirements while preserving visual quality for consumer delivery.[9][10] The sampling structure for Rec. 2020 signals is progressive scan with square pixels, deriving horizontal and vertical sampling frequencies from the image resolution, frame rate, and blanking intervals to maintain timing synchronization. For UHDTV level 1 (3840 × 2160 pixels), the luma sampling frequency (pixel clock) is determined by active picture size, blanking intervals, and frame rate; for example, at 60 Hz with standard blanking (4400 pixels per line, 2250 lines per frame), MHz for full-rate luma sampling in uncompressed interfaces. A specific case for 4K at 30 fps in 4:2:0 yields 74.25 MHz per effective channel in multi-link configurations. Vertical sampling aligns with the frame rate and total line count (e.g., 2250 lines including blanking for 60 Hz systems).[9][11] Signal formats under Rec. 2020 support both RGB (R'G'B') for high-end production workflows and luma-chroma (YCbCr) representations, including constant-luminance Y'C'C'BC'C'RC' for precise luminance preservation and non-constant-luminance Y'C'B'C'R' for backward compatibility with legacy SDTV and HDTV systems. These are coded at 10 or 12 bits per component, suitable for studio environments using parallel or serial digital interfaces as defined in related standards like SMPTE ST 2036-1 for parallel and ITU-R BT.2077 for serial links. Contribution links, used for long-haul program exchange, prioritize uncompressed or lightly compressed formats in YCbCr 4:2:2 or 4:4:4 to maintain signal integrity over distances.[9][11]Colorimetry and Encoding
Primaries and White Point
Rec. 2020 defines a set of RGB primaries using hypothetical monochromatic wavelengths to achieve a wide color gamut, specified in the CIE 1931 xy chromaticity coordinates as follows: red at (0.708, 0.292), green at (0.170, 0.797), and blue at (0.131, 0.046). These primaries are designed to encompass approximately 75.8% of the CIE 1931 color space visible to the average human observer, significantly expanding beyond previous standards.[12] The reference white point for Rec. 2020 is Illuminant D65, with chromaticity coordinates x = 0.3127 and y = 0.3290, which aligns with the white points used in sRGB and Rec. 709 to ensure compatibility in color reproduction workflows. This choice maintains a neutral daylight-like illumination reference, facilitating consistent rendering across display systems. The resulting color gamut of Rec. 2020 is substantially wider than that of Rec. 709, fully encompassing the DCI-P3 gamut used in digital cinema and extending further to include more saturated colors, as visualized by the boundaries on the CIE xy chromaticity diagram. To convert between CIE XYZ tristimulus values and Rec. 2020 RGB, the forward transformation matrix (XYZ to RGB) is derived from these primaries and white point: This matrix enables precise color space transformations, with notable coefficients such as 1.7167 for the red component from X, reflecting the primaries' positioning.[12] By supporting this expansive gamut, Rec. 2020 allows for the accurate reproduction of vivid colors, such as deep reds and lush greens, that exceed the capabilities of narrower gamuts like Rec. 709, enhancing visual fidelity in ultra-high-definition content.Transfer Characteristics
Rec. 2020 specifies a non-linear opto-electronic transfer function (OETF) for standard dynamic range (SDR) content, identical to that in Rec. 709, to map linear light values E (0 to 1) to coded values E' (0 to 1). For 10-bit systems, the parameters are α = 1.099 and β = 0.018. The piecewise function is:- If E ≤ β: E' = 4.5 × E
- If E > β: E' = α × E^{0.45} - (α - 1)
RGB and Luma-Chroma Formats
Rec. 2020 supports RGB as its native color format, defined using the specified primaries and D65 white point, which can be represented in either linear light for applications like computer graphics and visual effects (VFX) or in gamma-corrected form (R'G'B') after application of the transfer characteristic for encoded video signals.[6] This RGB format enables wide color gamut (WCG) representation, allowing for more saturated colors compared to narrower gamuts like Rec. 709.[5] For compressed or bandwidth-efficient transmission, Rec. 2020 employs the YCbCr luma-chroma format, where the luma component Y is derived from gamma-corrected RGB values using weights optimized for the WCG:with all components normalized such that the peak value is 1.0.[6] These coefficients differ from those in Rec. 709 (0.2126, 0.7152, 0.0722) primarily due to the shifted green primary in Rec. 2020, which increases the green contribution to luma for better perceptual uniformity in WCG content.[5] The chroma components Cb and Cr represent blue-difference and red-difference signals, respectively, defined as:
These are computed such that Cb' and Cr' have a full swing from -0.5 to +0.5 in the normalized domain, centering at 0 for achromatic signals and enabling efficient subsampling like 4:2:2 or 4:2:0. The complete forward transformation from R'G'B' to Y'Cb'Cr' uses the following 3×3 matrix (non-constant luminance variant):
| R' | G' | B' | |
|---|---|---|---|
| Y' | 0.2627 | 0.6780 | 0.0593 |
| Cb' | -0.1396 | -0.3604 | 0.5000 |
| Cr' | 0.5000 | -0.4598 | -0.0402 |
| Y' | Cb' | Cr' | |
|---|---|---|---|
| R' | 1.0000 | 0.0000 | 1.4746 |
| G' | 1.0000 | -0.1646 | -0.5714 |
| B' | 1.0000 | 1.8814 | 0.0000 |
Color Management
Conversion Matrices
The conversion matrices for Rec. 2020 define the linear transformations between its RGB color space and the CIE 1931 XYZ tristimulus values, enabling accurate color representation across different systems. These matrices are derived from the Rec. 2020 primaries—red at (x=0.708, y=0.292), green at (x=0.170, y=0.797), and blue at (x=0.131, y=0.046)—and the D65 white point (x=0.3127, y=0.3290).[9] The forward transformation from linear Rec. 2020 RGB values (in the range [0, 1]) to XYZ is given by the following matrix, with coefficients specified to six decimal places to ensure sufficient precision for 10-bit and higher digital representations: [13] The inverse matrix converts XYZ back to linear Rec. 2020 RGB and is the matrix inverse of the above, yielding: [13] Since both Rec. 2020 and most target spaces like Rec. 709 use the D65 white point, no additional chromatic adaptation transform (e.g., Bradford or von Kries) is required; however, if converting to a space with a different white point such as D50, an adaptation matrix must be applied intermediately to maintain perceptual consistency.[9] To convert between Rec. 2020 and Rec. 709, the process cascades through the XYZ intermediate: first apply the Rec. 2020 RGB-to-XYZ matrix, then the Rec. 709 XYZ-to-RGB matrix (with coefficients 3.241003, -1.537399, -0.498616 for R; -0.969224, 1.875930, 0.041554 for G; and 0.055639, -0.204011, 1.057149 for B). Out-of-gamut colors in Rec. 2020, which exceed the smaller Rec. 709 gamut, are typically handled by clipping negative or values greater than 1 to 0 or 1, respectively, after the linear transformation to prevent invalid RGB outputs while preserving luminance where possible.[14] This clipping approach ensures compatibility but may introduce minor saturation loss in vivid colors.[14] These matrices are essential in post-production workflows for tasks such as color grading UHDTV content, where Rec. 2020 footage is transformed for compatibility with legacy Rec. 709 monitors or delivery formats, and in broadcast upconversion, enabling seamless exchange of program material between HDTV and UHDTV systems while maintaining colorimetric accuracy.[15] The six-decimal precision supports reliable computations in 10-bit pipelines, minimizing quantization errors during repeated transformations.[13]Gamut Mapping Techniques
Gamut mapping techniques are essential for rendering Rec. 2020 content on devices with narrower color gamuts, such as those limited to Rec. 709 or DCI-P3, by transforming out-of-gamut colors while minimizing perceptual distortion.[14] These methods often take linear RGB values from conversion matrices as input to identify and adjust colors exceeding the target gamut boundary.[14] ITU-R BT.2408 provides operational guidance for applying such techniques in UHDTV workflows, emphasizing consistency across production, distribution, and display stages.[16] Clip-based mapping represents a straightforward approach, where out-of-gamut colors are directly clipped to the nearest boundary of the target gamut, such as by desaturating toward the white point or scaling RGB values to prevent negative or super-unity components.[14] This method preserves hue in many cases but can lead to loss of detail in highly saturated areas, making it suitable for real-time applications where computational efficiency is prioritized over perceptual fidelity.[14] Perceptual mapping techniques aim to maintain the intended appearance by leveraging color appearance models like CIECAM02, which adjust tone values and saturation based on human visual perception under varying viewing conditions.[14] In Rec. 2020 workflows, CIECAM02 facilitates hue-preserving transformations from wide gamuts to narrower ones by mapping in a uniform color space, though it may introduce discontinuities in highly saturated regions if not combined with adaptive lightness adjustments.[17] Three-dimensional lookup tables (3D LUTs) are widely adopted for practical implementation, enabling real-time interpolation of Rec. 2020 RGB values to target gamuts like DCI-P3 or Rec. 709 in display pipelines.[16] These LUTs store precomputed mappings that account for both chromaticity and luminance, reducing processing overhead while allowing customization for specific workflows, as recommended in ITU-R BT.2408 for UHDTV production.[16] A key challenge in these techniques involves avoiding distortion in greens and cyans, which protrude most significantly beyond the Rec. 709 gamut and can result in unnatural desaturation or hue shifts during mapping to legacy displays.[14] Effective strategies, such as those in ITU-R BT.2407, incorporate hue alignment to mitigate these issues, ensuring vibrant foliage and aquatic tones retain perceptual accuracy.[14]Implementations and Adoption
Hardware and Broadcasting
High-end television models from manufacturers such as Sony, Samsung, and LG have supported Rec. 2020 color parameters since 2015, primarily through the integration of quantum dot enhancement films in LCD panels and later in OLED technologies.[18][19] These early implementations achieved 75-90% coverage of the BT.2020 gamut, leveraging quantum dots to expand color reproduction beyond traditional Rec. 709 limits.[19] By 2025, quantum dot OLED (QD-OLED) panels in flagship models from Samsung and Sony have reached up to 90.55% BT.2020 coverage, while LG's OLED evo series provides strong partial gamut support across most 4K televisions.[20][21] In broadcasting, NHK has conducted ongoing 8K trials in Japan since 2016, incorporating BT.2020 for wide color gamut (WCG) in Super Hi-Vision productions aimed at events like the 2020 Tokyo Olympics.[22][23] The BBC and European Broadcasting Union (EBU) have run pilots for UHD content using BT.2020, focusing on hybrid log-gamma (HLG) for backward compatibility in 4K transmissions across Europe.[24][25] Standards like ATSC 3.0 in North America and DVB-UHD in Europe explicitly incorporate BT.2020 to enable WCG delivery over terrestrial and satellite networks, supporting up to 12-bit color depth for enhanced broadcast quality.[26][27][28] Professional cameras and production equipment have adopted BT.2020 output capabilities since 2016, with ARRI's Alexa SXT series providing native support for Rec. 2020 color space in 4K workflows.[29] RED Digital Cinema cameras, through their Image Processing Pipeline 2 (IPP2), also facilitate BT.2020 workflows for high-end productions.[30] Color grading suites like Blackmagic Design's DaVinci Resolve offer native BT.2020 support, enabling seamless integration with hardware for post-production of WCG content.[31] Panel technologies like QD-OLED have advanced to achieve approximately 90% BT.2020 gamut coverage in 2023 models, demonstrating significant progress in display hardware for realizing the standard's full potential.[32]Software and Content Support
Adobe Premiere Pro and After Effects provide full support for Rec. 2020 color space workflows, including HDR editing and finishing, since version CC 2015.[33] This enables professionals to work with wide color gamut (WCG) media, import tagged ProRes files, and export in Rec. 2020 primaries using HEVC or other compatible codecs. FFmpeg and its libavcodec library have supported BT.2020 encoding and decoding since 2016, facilitating open-source handling of 10-bit and 12-bit video with Rec. 2020 colorimetry through filters like colorspace.[34] Major streaming platforms have integrated Rec. 2020 for select 4K HDR content. Netflix employs BT.2020 color primaries for HDR10 and Dolby Vision titles, including the 2019 nature documentary series Our Planet, which leverages the gamut for vibrant environmental visuals.[35] Amazon Prime Video similarly uses BT.2020 for 4K HDR deliveries, requiring submissions in Rec. 2020 container with PQ or HLG transfer functions for compatible titles.[36] YouTube supports partial WCG via Rec. 2020 primaries for HDR uploads, mandating 10-bit or 12-bit depth and metadata for PQ or HLG electro-optical transfer functions (EOTF).[37] Native Rec. 2020 content remains limited, consisting mainly of technical demonstrations and select nature documentaries that exploit the full gamut for saturated colors like deep greens and blues. By 2025, much of the 4K HDR catalog is mastered within a DCI-P3 subset of Rec. 2020 rather than utilizing the complete space, due to production constraints and display coverage limitations.[38] Web browsers offer varying levels of Rec. 2020 support through hardware-accelerated video decoding. Google Chrome enables HEVC hardware decoding for HDR content on Windows 8 and later with compatible GPUs, processing Rec. 2020 metadata since version 69 in 2018.[39] Firefox added hardware-accelerated HEVC support for Windows in version 134 (2024), extending to Linux and Android, with earlier VP9 HDR decoding available from 2018. Safari provides partial Rec. 2020 handling via the Metal API on Apple silicon and iOS devices, supporting HDR color spaces including wide gamut primaries for HEVC playback.[40] A key challenge in Rec. 2020 adoption is backward compatibility with legacy Rec. 709 displays, necessitating tone-mapping operators to compress the dynamic range and gamut while preserving perceptual quality and avoiding clipping or desaturation.[41] This process, often implemented in players and workflows, ensures HDR content remains viewable on SDR devices but can introduce artifacts if not carefully managed.Timeline and Current Status
Initial demonstrations of Rec. 2020 (BT.2020) capabilities took place at major industry events, including the NAB Show in 2013, where discussions and early workflows for the wide color gamut standard were presented. Further demos occurred at NAB 2015, showcasing monitors capable of reproducing BT.2020 content at 60p. Sony announced its first reference monitor supporting the BT.2020 color space, the BVM-X300, in 2015, covering approximately 81% of the gamut, marking an early milestone in hardware adoption. Consumer TVs with BT.2020 compatibility claims also emerged from Sony that year as part of their 4K lineup advancements.[42][43][44] Between 2016 and 2018, adoption accelerated with the specification of HDR10 in 2016, which utilized BT.2020 primaries for enhanced dynamic range in 4K content. Web browsers, including Chrome and Edge, introduced support for HDR playback and BT.2020 color spaces around 2018, enabling wider online delivery of compatible media. In Japan, NHK began 8K test broadcasts in 2016, culminating in the launch of permanent 8K services in December 2018, fully compliant with BT.2020 for wide color gamut and high dynamic range via HLG.[45][46][47] From 2019 to 2022, streaming platforms expanded BT.2020-enabled HDR offerings; Disney+ launched in November 2019 with 4K HDR titles mastered in the BT.2020 container for compatible devices. The COVID-19 pandemic disrupted on-location production, delaying new HDR content creation, but it spurred innovations in remote grading tools to maintain workflow continuity.[48][49] During 2023-2025, partial BT.2020 support proliferated in mid-range televisions, encompassing roughly 80% of the market segment with gamut coverage typically exceeding 70% of the standard. Growth in full-gamut BT.2020 content remained gradual, constrained by elevated production and mastering expenses. No significant revisions to the ITU-R BT.2020 recommendation were issued in this period, with the last update occurring in 2015.[50][1] As of 2025, approximately 90% of new 4K televisions advertise BT.2020 compatibility, although real-world average gamut coverage hovers at 70-80% due to panel limitations. The standard's ongoing relevance is increasingly linked to 8K television proliferation and AI-driven upscaling techniques that extend legacy content to wider gamuts.[51][52]Related Standards
Rec. 2100
Recommendation ITU-R BT.2100, first approved in July 2016 and revised as BT.2100-3 in February 2025, specifies image parameter values for high dynamic range (HDR) television systems used in production and international programme exchange.[53] It extends the capabilities of Recommendation ITU-R BT.2020 by incorporating HDR support for ultra-high definition television (UHDTV), enabling peak brightness levels up to 10,000 cd/m² (nits) to better represent real-world luminance ranges.[53] BT.2100 defines two primary transfer functions for HDR signal encoding. The Perceptual Quantizer (PQ) transfer function, based on SMPTE ST 2084, uses an absolute luminance scale and is given by the opto-electronic transfer function (OETF): Let , where is the absolute scene luminance in cd/m². Then, where , , , , .[53] This function optimizes perceptual uniformity across a wide dynamic range, supporting 10-bit or higher encoding for production. The Hybrid Log-Gamma (HLG) transfer function provides backward compatibility with standard dynamic range (SDR) displays by approximating legacy gamma curves while extending to HDR levels.[53] The system maintains the same colorimetry as BT.2020, including wide color gamut primaries and D65 white point, but supports HDR workflows that utilize metadata for content light levels, such as Maximum Frame-Average Light Level (MaxFALL) and Maximum Content Light Level (MaxCLL) as defined in complementary standards like SMPTE ST 2086. These are conveyed in Supplemental Enhancement Information (SEI) messages for High Efficiency Video Coding (HEVC).[53][54][55] These parameters help displays optimize tone mapping without exceeding mastering intent. BT.2100 supports levels for UHD-1 (3840 × 2160) and UHD-2 (7680 × 4320) resolutions with HDR, alongside 1920 × 1080 for transitional use, all in progressive scan at frame rates up to 120 Hz.[53] HLG enables dual-layer broadcasts, where HDR content appears as enhanced SDR on legacy receivers. In consumer products, BT.2100 is frequently implemented alongside BT.2020 as "BT.2020 HDR" for televisions and streaming devices supporting formats like HDR10.[53][54]Comparisons with Predecessor Standards
Rec. 2020, also known as BT.2020, represents a significant advancement over its predecessor Rec. 709 (BT.709), the standard for high-definition television (HDTV). While both share a similar gamma curve based on a power-law transfer function, Rec. 709 typically employs 8-bit color depth, limiting it to approximately 16.7 million colors, whereas Rec. 2020 supports 10-bit or 12-bit depth, enabling over 1 billion colors at 10 bits for smoother gradients and reduced banding.[56][57][58] Additionally, Rec. 709 is confined to 1080p resolution, whereas Rec. 2020 extends to 4K (3840×2160) and 8K (7680×4320) formats, supporting ultra-high-definition television (UHDTV) production and exchange.[56][57] The color gamut of Rec. 709 covers only about 35% of the NTSC 1953 gamut, making it narrower and less capable of reproducing vibrant natural scenes, such as skin tones or foliage, compared to Rec. 2020's 76% coverage of the same reference.[45] In comparison to DCI-P3, the color space used in digital cinema, Rec. 2020 offers a broader gamut that fully encompasses DCI-P3 while adding approximately 25% more colors, particularly in greens and cyans, for enhanced realism in theatrical content adapted to broadcast.[59] DCI-P3 exceeds Rec. 709 in width but remains a subset of Rec. 2020, with DCI-P3 employing 12-bit depth and a distinct white point (approximately 6300K xenon-based) versus Rec. 2020's D65 (6500K) illuminant.[60][56] This positioning allows Rec. 2020 to bridge cinema and consumer video more effectively, though conversions between them require gamut mapping to minimize clipping or desaturation.[61] The primaries of Rec. 2020 are defined to enclose nearly all real-world colors, including the full Adobe RGB space and most spectral loci, providing superior coverage of 75.8% of the CIE 1931 color space compared to Rec. 709's 35.9% and DCI-P3's 53.6%.[62][63] This expanded gamut improves representation of natural elements like skin tones and landscapes by capturing more saturated hues without significant conversion losses when mapping from narrower spaces, though perceptual mapping techniques are essential to preserve intent.[61][59]| Standard | Primary Resolution | Bit Depth | Gamut Coverage (% of CIE 1931) |
|---|---|---|---|
| Rec. 709 | 1920×1080 (1080p) | 8-bit (typical) | 35.9% |
| DCI-P3 | Variable (cinema) | 12-bit | 53.6% |
| Rec. 2020 | 3840×2160 (4K) or 7680×4320 (8K) | 10-bit or 12-bit | 75.8% |