View source for EBU colour bars

{{Short description|Television test card}}
{{Use dmy dates|date=December 2022}}

[[File:EBU Colorbars.svg|thumb|[[European Broadcasting Union|EBU]]/[[Independent Broadcasting Authority|IBA]] 100/0/75/0 Colour Bars'' <small>Displayed colours are only approximate due to different transfer and colour spaces used on web pages ([[sRGB]]) and video ([[Rec. 601|BT.601]] or [[Rec. 709|BT.709]])</small>'']] 
[[File:Barras_YUV.JPG|thumb|EBU Colour Bars as displayed on a [[Tektronix]] [[waveform monitor]] and [[vectorscope]]]]
[[File:Test-Mire1.jpg|thumb|EBU Colour Bars transmitted from a digital point-to-point satellite link ([[DVB-S]]) operated by [[Globecast]]]]
 
The '''[[European Broadcasting Union|EBU]] colour bars''' are a television [[test card]] used to check if a [[video signal]] has been altered by recording or transmission, and what adjustments must be made to bring it back to specification. It is also used for setting a television monitor or receiver to reproduce [[chrominance]] and [[Luminance (video)|luminance]] information correctly. The EBU bars are most commonly shown arranged side-by-side in a vertical manner (as in the images in this article), though some broadcasters – such as [[Telewizja Polska|TVP]]<ref>{{Cite web|url=https://fmtvdx.eu/tv/europesch-testbeelden/|title=Europesche-testbeelden, Radio Bulletin 1972|website=fmtvdx.eu}}</ref> in Poland, and [[Radio Télévision Gabonaise|Gabon Télévision]]<ref>{{Cite web|url=https://www.youtube.com/watch?v=vcIC7WyNmRo|title=TV-DX RTG C2 Gabon Television 05.12.1993|via=www.youtube.com}}</ref> in Gabon – were known to have aired a horizontal version of the EBU bars.

It is similar to the [[SMPTE color bars]], although that pattern is typically associated with the [[NTSC]] analogue colour TV system. Many test cards, such as [[Philips PM5544]] or [[Telefunken FuBK]], feature elements equivalent to the EBU colour bars.

==75% Colour Bars==
[[File:EBU Colorbars 75 0 75 0.svg|thumb|EBU 75/0/75/0 Colour Bars pattern'' <small>Displayed colours are only approximate due to different transfer and colour spaces used on web pages ([[sRGB]]) and video ([[Rec. 601|BT.601]] or [[Rec. 709|BT.709]])</small>'']]
The '''75% Colour Bars''' or '''EBU/[[Independent Broadcasting Authority|IBA]] 100/0/75/0 Colour Bars''' pattern<ref>{{cite web|url=http://www.channel6.dk/mainsite/EN/Page421.html |title=Channel 6 Television Denmark – Test patterns (English) |website=Channel6.dk |date=14 December 2016 |accessdate=2022-02-17}}</ref><ref>{{cite web|url=http://www.channel6.dk/mainsite/Downloads/Test%20patterns%20HD/EBU%20BAR%20HD.jpg |format=JPG|title=Photographic image of colour bars|website=Channel6.dk|access-date=2022-02-23}}</ref><ref name="BT.471">{{cite web|url=https://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.471-1-198607-I!!PDF-E.pdf |title=RECOMMENDATION ITU-R BT.471-1* – Nomenclature and description of colour bar signals |website=Itu.int |date= |accessdate=2022-02-17}}</ref> is very similar to the SMPTE colour bars pattern, although it only features seven colour bars, and the white bar is at 100% intensity.

There is a variant where the white bar is also at 75% intensity ('''EBU 75/0/75/0'''). This pattern is generated by certain types of test equipment – including the '''Philips PM5519'''.<ref>{{Cite web|url=https://www.testequipmenthq.com/datasheets/PHILIPS-PM5519-Datasheet.pdf|title=Philips PM 5519 datasheet|website=testequipmenthq.com}}</ref>

The signal values of these bars for the [[PAL]] analogue system are:<ref>{{Cite web|url=https://www.testequipmenthq.com/datasheets/PHILIPS-PM5519-Datasheet.pdf|title=Philips PM 5519 datasheet, p.3|website=testequipmenthq.com}}</ref>
{| class="wikitable"
!
! Luminance
! Chroma amplitude
! Chroma Φ
|-----
| style="background-color: #ffffff;"| White 100/0/75/0
| 1.00
| –
| –
|-
| style="background-color: #bbbbbb;"| White 75/0/75/0
| 0.75
| –
| –
|-
| style="background-color: #bdbd12; "| Yellow
| 0.67
| 0.33
| 167º
|-
| style="background-color: #00bcbc;"| Cyan
| 0.53
| 0.47
| 283º
|-----
| style="background-color: #00bd12; "| Green
| 0.44
| 0.44
| 241º
|-
| style="background-color: #c000bc; color: white  "| Magenta
| 0.31
| 0.44
| 61º
|-----
| style="background-color: #c00000; color: white "| Red
| 0.23
| 0.47
| 103º
|-
| style="background-color: #0000bb; color: white "| Blue
| 0.08
| 0.33
| 347º
|-
| style="background-color: #000000; color: white "| Black
| 0
| –
| –
|}
<small>''Displayed colours are converted from the original PAL BT.601 colour space to sRGB – the colour space used on web pages. They are only approximate, giving a notion of how the bars would look on a calibrated PAL display.''</small>

==100% Colour Bars==
[[File:EBU Colorbars HD.svg|thumb|[[European Broadcasting Union|EBU]] 100/0/100/0 Colour Bars'' <small>Displayed colours are only approximate due to different transfer and colour spaces used on web pages ([[sRGB]]) and video ([[Rec. 601|BT.601]] or [[Rec. 709|BT.709]])</small>'']] 
An alternate form of colour bars is the '''100% Colour Bars''' or '''EBU 100/0/100/0 Colour Bars''' pattern (specified in ITU-R Rec. BT.1729<ref name="auto">{{cite web|title=BT.1729 : Common 16:9 or 4:3 aspect ratio digital television reference test pattern|url=https://www.itu.int/rec/R-REC-BT.1729/|access-date=2022-02-14|website=Itu.int}}</ref>), also known as the '''[[RGB color model|RGB]] pattern '''or '''full field bars''', which consists of eight vertical bars of 100% intensity, and does not include the castellation or luminance patterns. Like the SMPTE colour bars pattern, the colour order is white, yellow, cyan, green, magenta, red, and blue – but with an additional column of saturated black. This pattern is used to check peak colour levels, and colour saturation, as well as colour alignment. The 100% pattern is not as common as the SMPTE bars, or the above-mentioned EBU 75% pattern, but many pieces of test equipment can be selected to generate either one. Many professional cameras can be set to generate a 100% pattern for calibration of broadcast or recording equipment, especially in a multi-camera installation where all camera signals must match.

===Standard Definition===
EBU colour bar values for [[standard-definition television]] systems following [[BT.601]], as specified in ITU-R Rec. BT.1729:<ref name="auto2">{{Cite web |title=BT.1729: Common 16:9 or 4:3 aspect ratio digital television reference test pattern |url=https://www.itu.int/rec/R-REC-BT.1729-0-200504-I/en |access-date=2022-04-12 |website=www.itu.int |page=18}}</ref>
{| class="wikitable"
|+10-bit digital [[YCbCr]] values for 100/0/100/0 bars on SD systems
! 
! Y
! Cb
! Cr
|-
| style="background-color:#fff; color:#000" | White
| 940
| 512
| 512
|-
| style="background-color:#ffff1c; color:#000" | Yellow
| 840
| 64
| 585
|-
| style="background-color:#00ffff; color:#000" | Cyan
| 678
| 663
| 64
|-
| style="background-color:#00ff1c; color:#000" | Green
| 578
| 215
| 137
|-
| style="background-color:#ff00fe; color:#fff" | Magenta
| 426
| 809
| 887
|-
| style="background-color:#ff0000; color:#fff" | Red
| 326
| 361
| 960
|-
| style="background-color:#0000fe; color:#fff" | Blue
| 164
| 960
| 439
|-
| style="background-color:#000000; color:#fff" | Black
| 64
| 512
| 512
|}
<small>''Displayed colours are converted from the original PAL BT.601 colour space to sRGB – the colour space used on web pages. They are only approximate, but represent what is seen on a properly calibrated display using the original colour space.''</small>

Calculation of <math>Y</math> ([[luminance]]) and  <math>C_B C_R</math> ([[YCbCr|colour difference]]) signals from  <math>R'</math>,  <math>G' </math> and  <math>B'</math> components according to BT.601 is as follows:<ref name="auto1">{{Cite web |title=BT.1729: Common 16:9 or 4:3 aspect ratio digital television reference test pattern |url=https://www.itu.int/rec/R-REC-BT.1729-0-200504-I/en |access-date=2022-04-12 |website=www.itu.int |page=10}}</ref>

:<math>\begin{align}
 Y' &=  0.299  \cdot R' + 0.587  \cdot G' + 0.114  \cdot B'\\
 C_B ' &=  0.564 \cdot (B' - Y')\\
 C_R ' &=  0.713 \cdot (R' - Y')\\
\end{align}</math>

===High Definition===
EBU colour bar values for [[High-definition television|high definition]] TV systems following [[BT.709]], as specified in ITU-R Rec. BT.1729:<ref name="auto2"/>
{| class="wikitable"
|+10-bit digital [[YCbCr]] values for 100/0/100/0 bars on HD systems
!
! Y
! Cb
! Cr
|-
| style="background-color:#fff; color:#000" | White
| 940
| 512
| 512
|-
| style="background-color:#ffff00; color:#000" | Yellow
| 877
| 64
| 553
|-
| style="background-color:#00ffff; color:#000" | Cyan
| 754
| 615
| 64
|-
| style="background-color:#00ff00; color:#000" | Green
| 691
| 167
| 105
|-
| style="background-color:#ff00ff; color:#fff" | Magenta
| 313
| 857
| 919
|-
| style="background-color:#ff0000; color:#fff" | Red
| 250
| 409
| 960
|-
| style="background-color:#0000ff; color:#fff" | Blue
| 127
| 960
| 471
|-
| style="background-color:#000000; color:#fff" | Black
| 64
| 512
| 512
|}

Calculation of <math>Y</math> (luminance) and  <math>C_B C_R</math> (colour difference) signals from  <math>R'</math>,  <math>G' </math> and  <math>B'</math> components according to BT.709 is as follows:<ref name="auto1" />

:<math>\begin{align}
 Y' &=  0.2126  \cdot R' + 0.7152  \cdot G' + 0.0722  \cdot B'\\
 C_B ' &=  (B' - Y') / 1.8556\\
 C_R ' &=  (R' - Y') / 1.5748\\
\end{align}</math>

== HDR UHDTV ==
In 2020 the EBU published a newer colour bar pattern named '''Colour Bars for Use in the Production of Hybrid Log Gamma (HDR) UHDTV''', designed for [[High-dynamic-range television|HDR]] broadcasts, taking into account the extended [[Gamut|colour gamut]] of these systems.<ref name=":0">{{Cite book |url=https://tech.ebu.ch/files/live/sites/tech/files/shared/tech/tech3373.pdf |title=EBU Tech 3373 – COLOUR BARS FOR USE IN THE PRODUCTION OF HYBRID-LOG GAMMA (HDR) UHDTV |publisher=EBU |year=2020}}</ref> It includes 100% and 75% ITU-R [[Rec. 2100|BT.2100]] [[Hybrid log–gamma|HLG]] colour bars, and colour bars which can be converted to ITU-R [[Rec. 709|BT.709]] 75% bars when ''scene-light'' and ''display-light'' mathematical transforms defined in ITU-R BT.2408 are used.<ref name=":0" />

This pattern allows testing of [[Ultra-high-definition television|UHDTV]] to [[High-definition television|HDTV]] conversion, measuring luminance response, saturation and hue shifts, and checking near‑black performance. It can also be used to check for correct hardware settings, transmission chain errors, and proper [[Color space|colour space]] transforms from ITU‑R BT.2100 HLG to ITU‑R BT.709.<ref name=":0" /> Versions of the pattern are freely available as a still image<ref>{{Cite book|url=https://tech.ebu.ch/publications/tech3373-tiff|title=(U)HDTV HDR BT.2100 HLG Colour Bars (TIFF)|date=17 April 2020|via=tech.ebu.ch}}</ref> or video file.<ref>{{Cite book|url=https://tech.ebu.ch/publications/tech3373-v210|title=(U)HDTV HDR BT.2100 HLG Colour Bars (QT v210)|date=3 July 2020|via=tech.ebu.ch}}</ref>

The pattern is similar to the [[ITU-R]] recommendation '''BT.2111''' that also covers the [[Perceptual quantizer|PQ]] transfer function.<ref>{{Cite book |url=https://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.2111-2-202012-I!!PDF-E.pdf |title=Recommendation ITU-R BT.2111-2 |publisher=ITU-R |year=2020}}</ref> Another similar pattern named '''Colour Bar Test Pattern for Hybrid Log-Gamma (HLG) High Dynamic Range Television (HDR-TV) System''' was developed by [[Association of Radio Industries and Businesses|ARIB]] in 2018 (ARIB STD-B72), based on the [[SMPTE color bars]] commonly used in Japan and United States.<ref>{{Cite web |title=About obtaining ARIB Standards (STD-B72)｜Association of Radio Industries and Businesses |url=https://www.arib.or.jp/english/std_tr/broadcasting/std-b72.html |access-date=2024-01-24 |website=www.arib.or.jp}}</ref>

==See also==
{{Portal|Television}}
{{Commons category|EBU Colorbars}}
* [[SMPTE color bars]]
* [[Indian-head test pattern]]
* [[Test Card F]]
* [[Philips PM5544]]
* [[Telefunken FuBK]]

==References==
{{Reflist}}

==External links==
* [https://web.archive.org/web/20160303174447/http://www.pembers.freeserve.co.uk/Test-Cards/Test-Card-Technical.html#Bars Colour Bars and PLUGE]

{{standard test item}}
{{European Broadcasting Union}}

[[Category:Test cards]]
[[Category:Television terminology]]
[[Category:European Broadcasting Union]]