ITU-R Recommendation BT.2020, more commonly known by the abbreviations Rec. 2020 or BT.2020, defines various aspects of UHDTV such as display resolution, frame rate, chroma subsampling, bit depth, and color space. It was posted on the International Telecommunication Union (ITU) website on August 23, 2012

 

 Recommendation ITU-R BT.2020

(08/2012) 

Parameter values for ultra-high definition television systems for production and international programme exchange

 

BT Series

Broadcasting service television

The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economical use of the radio-frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted.

The regulatory and policy functions of the Radiocommunication Sector are performed by World and Regional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups.

Policy on Intellectual Property Right (IPR)

ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of Resolution ITU-R 1. Forms to be used for the submission of patent statements and licensing declarations by patent holders are available from http://www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU‑T/ITU‑R/ISO/IEC and the ITU-R patent information database can also be found.

  

Series of ITU-R   Recommendations

(Also available online at http://www.itu.int/publ/R-REC/en)

Series

Title

BO

Satellite delivery

BR

Recording   for production, archival and play-out; film for television

BS

Broadcasting   service (sound)

BT

Broadcasting service   (television)

F

Fixed service

M

Mobile, radiodetermination,   amateur and related satellite services

P

Radiowave propagation

RA

Radio astronomy

RS

Remote sensing   systems

S

Fixed-satellite service

SA

Space applications and   meteorology

SF

Frequency sharing and   coordination between fixed-satellite and fixed service systems

SM

Spectrum management

SNG

Satellite news gathering

TF

Time signals and frequency   standards emissions

V

Vocabulary and related subjects

 

 

Note: This ITU-R   Recommendation was approved in English under the procedure detailed in   Resolution ITU-R 1.

 

 

Parameter values for ultra-high definition television systems for production and international programme exchange

 

Scope

Ultra-high definition television (UHDTV) will provide viewers with an enhanced visual experience primarily by having a wide field of view both horizontally and vertically with appropriate screen sizes relevant to usage at home and in public places. UHDTV applications require system parameters that go beyond the levels of HDTV. This Recommendation specifies UHDTV image system parameters for production and international programme exchange.

 

The ITU Radiocommunication Assembly, considering

a) that digital terrestrial television broadcasting (DTTB) service has been introduced by some administrations since 1997 and can provide high quality television programmes through HDTV systems;

 

b) that viewers expect future TV systems beyond HDTV to provide improved characteristics compared with the current HDTV systems in terms of a more realistic sensation, greater transparency to the real world, and more accurate visual information;

 

c) that ultra-high definition television (UHDTV) is expected to become available in the near future with, inter alia, larger screens, higher spatial/temporal resolution, wider colour gamut, wider dynamic range, etc. taking into account developments of display technology;

 

d) that ITU‑R has been studying extremely high-resolution imagery (EHRI) and an expanded hierarchy of large screen digital imagery (LSDI) image formats and has established ITU‑R Recommendations: Recommendation ITU-R BT.1201-1 providing the guidelines of image characteristics for extremely high-resolution imagery, and Recommendation ITU-R BT.1769 offering the parameter values for an expanded hierarchy of LSDI image formats;

 

e) that LSDI is a system providing a display on a very large screen, typically for public viewing. This can be used in a wide variety of applications including programme presentations such as dramas, plays, sporting events, concerts, etc.;

 

f) that EHRI is a system offering higher resolution than HDTV and can be used for both broadcasting and non-broadcasting applications (e.g. computer graphics, printing and medical applications);

 

g) that UHDTV provides viewers with an enhanced visual experience primarily by a wider field of view that covers a considerable part of the human natural visual field with appropriate screen sizes relevant to usage at home and in public places;

 

h) that signal formats contributing to increasing the compression efficiency are desirable for UHDTV systems since they have a larger number of pixels than HDTV systems,

 

recommends

 

1 that for UHDTV programme production and international exchange, the specifications described in this Recommendation should be used[1], and further recommends

 

2 that if it is shown that an alternative electro-optical transfer function (EOTF) will provide significant benefits without also imposing significant disadvantages, then this Recommendation should be extended to enable use with an improved EOTF.

 

NOTE – Future consideration should be given to extend this Recommendation in a complementary manner to include extended image parameters.

 

TABLE 1

 

Picture spatial characteristics

 

Parameter

Values

Picture   aspect ratio

16:9

Pixel count

Horizontal ×   vertical

7 680 × 4 320

3 840 × 2 160

Sampling   lattice

Orthogonal

Pixel aspect   ratio

1:1 (square pixels)

Pixel   addressing

Pixel ordering in each row is from left to right, and rows   are ordered from top to bottom.

 

 

TABLE 2

 

Picture temporal characteristics

 

Parameter

Values

Frame   frequency (Hz)

120, 60, 60/1.001, 50, 30, 30/1.001, 25, 24,   24/1.001

Scan mode

Progressive

 

TABLE 3

 

System colorimetry

 

Parameter

Values

Opto-electronic   transfer
  characteristics before
  non-linear pre-correction

Assumed   linear (1)

Primary   colours and reference white (2)

Chromaticity   coordinates
  (CIE, 1931)

x

y

Red primary (R)

0.708

0.292

Green primary (G)

0.170

0.797

Blue primary (B)

0.131

0.046

Reference white (D65)

0.3127

0.3290

(1)    Picture information can be linearly   indicated by the tristimulus values of RGB in the range of 0-1.

(2)    The colorimetric values of the picture   information can be determined based on the reference RGB primaries and the   reference white.

 

TABLE 4

Signal format

 

Parameter

Values

Signal format

R'G'B'[2]

Constant luminance
  Y’CC’BCC’RC   [3]

Non-constant luminance
  Y’C’BC’R[4]

Non-linear   transfer function

                                                                     

where E is voltage normalized by the reference white   level and proportional to the implicit light intensity that would be detected   with a reference camera colour channel R,   G, B; E' is the resulting non-linear signal.

α = 1.099 and β = 0.018 for 10-bit system
  α =   1.0993 and β = 0.0181 for 12-bit system


 

 TABLE 4 (end)

 

Parameter

Values

Derivation of Y’C and Y’

    

    

Derivation of colour   difference signals

    

    

 

 

TABLE 5

 Digital representation

 

Parameters

Values

Coded signal

R', G', B' or Y', C'B, C'R or Y'C, C'BC,   C'RC

Sampling lattice

R', G', B', Y', Y'C

Orthogonal, line and picture repetitive co-sited

Sampling lattice

C'B,   C'R or C'BC, C'RC

Orthogonal, line and picture repetitive co-sited   with each other.

The first (top-left) sample is co-sited with the   first Y’ samples.

4:4:4 system

4:2:2 system

4:2:0 system

Each has the same number of horizontal samples as   the Y' (Y'C)   component.

Horizontally
  subsampled by a factor of two with respect to
  the Y' (Y'C) component.

Horizontally and vertically subsampled by a factor   of two with respect to the Y' (Y'C)   component.

Coding format

10 or 12   bits per component

Quantization of R', G', B', Y', Y'C , C'B, C'R, C'BC,   C'RC

    

    

    

    

    

    


 

 

TABLE 5 (end)

 

Parameters

Values

Quantization levels

 

–   Black level

     DR',   DG', DB', DY', DY'C

–   Achromatic

     DC'B,   DC'R , DC'BC,   DC'RC

–   Nominal   Peak

     DR',   DG', DB', DY', DY'C

     DC'B,   DC'R, DC'BC, DC'RC

10-bit coding

12-bit coding

 

 

64

 

512
 
 

 

940

64 and 960

 

 

256

 

2 048


 
 

3 760

256 and 3 840

Quantization level   assignment

–   Video data

–   Timing   reference

10-bit coding

12-bit coding

4 through 1 019

0-3 and 1 020-1 023

16 through 4 079

0-15 and 4 080-4 095

 



[1] Both 3840 × 2160 and 7680 × 4320 systems of UHDTV will find their main applications for the delivery of television programming to the home where they will provide viewers with an increased sense of “being there” and increased sense of realness by using displays with a screen diagonal of the order of 1.5 metres or more and for large screen (LSDI) presentations in theatres, halls and other venues such as sports venues or theme parks.

Presentation on tablet displays with extremely high resolution will also be attractive for viewers.

The 7680 × 4320 system will provide a more enhanced visual experience than the 3840 × 2160 system for a wider range of viewing environments.

An increase in the efficiency of video source coding and/or in the capacity of transmission channels, compared to those currently in use, will likely be needed to deliver such programs by terrestrial or satellite broadcasting to the home. Research is under way to achieve this goal. The delivery of such programming will initially be possible by cable or fibre.

[2] R'G'B' may be used for programme exchange when the best quality programme production is of primary importance.

[3] Constant luminance Y'CC'BCC'RC may be used when the most accurate retention of luminance information is of primary importance or where there is an expectation of improved coding efficiency for delivery (see Report ITU-R BT.2246).

[4] Conventional non-constant luminance Y'C'BC'R may be used when use of the same operational practices as those in SDTV and HDTV environments is of primary importance through a broadcasting chain (see Report ITU-R BT.2246).

 

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