RGB color spaces: Difference between revisions

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{{short description|Any additive color space based on the RGB color model}}
{{Short description|Any additive color space based on the RGB color model}}
{{more citations needed|date=December 2014}}
{{More citations needed|date=December 2014}}
[[File:CIE1931xy_gamut_comparison.svg |thumb|300px|1931 CIE chromaticity diagram showing some RGB color spaces as defined by their chromaticity triangles]]
[[File:CIE1931xy_gamut_comparison.svg|thumb|300px|1931 CIE chromaticity diagram showing some RGB color spaces as defined by their chromaticity triangles]]


'''<abbr title="red–green–blue">RGB</abbr> color spaces''' are a category of [[Additive color|additive]] colorimetric [[color space]]s<ref>{{cite web |title=colorimetric colour space (definition) |url=https://cie.co.at/eilvterm/17-23-042 |location=France |publisher= International Commission on Illumination (CIE)|access-date=8 October 2023}}</ref> specifying part of its absolute color space definition using the [[RGB color model]].<ref>{{cite web|author=Pascale, Danny|url=http://www.babelcolor.com/download/A%20review%20of%20RGB%20color%20spaces.pdf|title=A Review of RGB color spaces...from xyY to R'G'B'|access-date=20 October 2021}}</ref>
'''<abbr title="red–green–blue">RGB</abbr> color spaces''' are a category of [[Additive color|additive]] colorimetric [[color space]]s<ref>{{cite web |title=colorimetric colour space (definition) |url=https://cie.co.at/eilvterm/17-23-042 |location=France |publisher=International Commission on Illumination (CIE) |access-date=8 October 2023}}</ref> specifying part of its absolute color space definition using the [[RGB color model]].<ref>{{cite web |author=Pascale, Danny |url=http://www.babelcolor.com/download/A%20review%20of%20RGB%20color%20spaces.pdf |title=A Review of RGB color spaces...from xyY to R'G'B' |access-date=20 October 2021}}</ref>


RGB color spaces are commonly found describing the mapping of the RGB color model to human perceivable color, but some RGB color spaces use imaginary (non-real-world) primaries and thus can not be displayed directly.
RGB color spaces are commonly found describing the mapping of the RGB color model to human perceivable color, but some RGB color spaces use imaginary (non-real-world) primaries and thus can not be displayed directly.


Like any color space, while the specifications in this category use the RGB color model to describe their space, it is not mandatory to use that model to signal pixel color values. Broadcast TV color spaces like NTSC, PAL, Rec. 709, Rec. 2020 additionally describe a translation from RGB to YCbCr and that is how they are usually signalled for transmission, but an image can be stored as either RGB or YCbCr. This demonstrates using the singular term "RGB color space" can be misleading, since a chosen color space or signalled colour can be described by any appropriate color model. However the singular can be seen in specifications where storage signalled as RGB is its intended use.
Like any color space, while the specifications in this category use the RGB color model to describe their space, it is not mandatory to use that model to signal pixel color values. Broadcast TV color spaces like [[NTSC]], [[PAL]], [[Rec. 709]], [[Rec. 2020]] additionally describe a translation from RGB to [[YCbCr]] and that is how they are usually signalled for transmission, but an image can be stored as either RGB or YCbCr. This demonstrates using the singular term "RGB color space" can be misleading, since a chosen color space or signalled colour can be described by any appropriate color model. However the singular can be seen in specifications where storage signalled as RGB is its intended use.


==Definition==
== Definition ==
[[File:RGB Cube Show lowgamma cutout b.png|thumb|300px|RGB cube]]
[[File:RGB Cube Show lowgamma cutout b.png|thumb|300px|RGB cube]]
The normal human eye contains three types of color-sensitive [[cone cell]]s. Each cell is responsive to light of either long, medium, or short wavelengths, which we generally categorize as red, green, and blue. Taken together, the responses of these cone cells are called the [[CIE 1931 color space#Tristimulus values|Tristimulus values]], and the combination of their responses is processed into the psychological effect of color vision.
The normal human eye contains three types of color-sensitive [[cone cell]]s. Each cell is responsive to [[light]] of either long, medium, or short [[Wavelength|wavelengths]], which we generally categorize as red, green, and blue. Taken together, the responses of these cone cells are called the [[CIE 1931 color space#Tristimulus values|Tristimulus values]], and the combination of their responses is processed into the psychological effect of color vision.


RGB use in color space definitions employ primaries (and often a white point) based on the RGB color model, to map to real world color. Applying [[Grassmann's laws (color science)|Grassmann's law]] of light additivity, the range of colors that can be produced are those enclosed within the triangle on the chromaticity diagram defined using the primaries as [[Vertex (geometry)|vertices]].<ref>{{cite book|last=Hunt|first=R. W. G|title=The Reproduction of Colour (6th ed.)|year=2004|publisher=Chichester UK: Wiley–IS&T Series in Imaging Science and Technology|isbn=0-470-02425-9|url-access=registration|url=https://archive.org/details/reproductionofco0000hunt}}</ref>
RGB use in color space definitions employ primaries (and often a [[white point]]) based on the RGB color model, to map to real world color. Applying [[Grassmann's laws (color science)|Grassmann's law]] of light additivity, the range of colors that can be produced are those enclosed within the triangle on the chromaticity diagram defined using the primaries as [[Vertex (geometry)|vertices]].<ref>{{cite book |last=Hunt |first=R. W. G |title=The Reproduction of Colour (6th ed.) |year=2004 |publisher=Chichester UK: Wiley–IS&T Series in Imaging Science and Technology |isbn=0-470-02425-9 |url-access=registration |url=https://archive.org/details/reproductionofco0000hunt}}</ref>


The primary colors are usually mapped to [[xyY]] chromaticity coordinates, though the '''uʹ,vʹ''' coordinates from the UCS chromaticity diagram may be used. Both xyY and uʹ,vʹ are derived from the [[CIE 1931 color space]], a device independent space also known as '''XYZ''' which covers the full [[gamut]] of human-perceptible colors visible to the [[CIE 1931 color space#CIE standard observer|CIE 2° standard observer]].
The primary colors are usually mapped to [[CIE 1931 color space#CIE xyY color space|xyY]] chromaticity coordinates, though the '''uʹ,vʹ''' coordinates from the UCS chromaticity diagram may be used. Both xyY and uʹ,vʹ are derived from the [[CIE 1931 color space]], a device independent space also known as '''XYZ''' which covers the full [[gamut]] of human-perceptible colors visible to the [[CIE 1931 color space#CIE standard observer|CIE 2° standard observer]].


==Applications==
== Applications ==
{{See also|List of color spaces and their uses|label 1 = List of Color Spaces}}
{{See also|List of color spaces and their uses|label 1 = List of Color Spaces}}
[[Image:1Mcolors.png|thumbnail|100px|left|One million colors in RGB space, visible in full-size image]]
[[File:1Mcolors.png|thumb|100px|left|One million colors in RGB space, visible in full-size image]]
<!-- There should probably be a mention of the CIE 1931 RGB space here, with an explanation of its use. -->
<!-- There should probably be a mention of the CIE 1931 RGB space here, with an explanation of its use. -->
RGB color spaces are well-suited to describing the electronic display of color, such as [[computer monitors]] and [[color television]]. These devices often reproduce colours using an array of red, green, and blue phosphors agitated by a [[cathode-ray tube]] (CRT), or an array of red, green, and blue [[LCD]]s lit by a backlight, and are therefore naturally described by an additive color model with RGB primaries.
 
RGB color spaces are well-suited to describing the electronic display of color, such as [[Computer monitor|computer monitors]] and [[color television]]. These devices often reproduce colours using an array of red, green, and blue phosphors agitated by a [[cathode-ray tube]] (CRT), or an array of red, green, and blue [[Liquid-crystal display|LCD]]s lit by a backlight, and are therefore naturally described by an additive color model with RGB primaries.


Early examples of RGB color spaces came with the adoption of the [[NTSC]] color television standard in 1953 across North America, followed by [[PAL]] and [[SECAM]] covering the rest of the world. These early RGB spaces were defined in part by the phosphor used by CRTs in use at the time, and the gamma of the electron beam. While these color spaces reproduced the intended colors using additive red, green, and blue primaries, the broadcast signal itself was encoded from RGB components to a composite signal such as [[YIQ]], and decoded back by the receiver into RGB signals for display.
Early examples of RGB color spaces came with the adoption of the [[NTSC]] color television standard in 1953 across North America, followed by [[PAL]] and [[SECAM]] covering the rest of the world. These early RGB spaces were defined in part by the phosphor used by CRTs in use at the time, and the gamma of the electron beam. While these color spaces reproduced the intended colors using additive red, green, and blue primaries, the broadcast signal itself was encoded from RGB components to a composite signal such as [[YIQ]], and decoded back by the receiver into RGB signals for display.


[[HDTV]] uses the [[BT.709]] color space, later repurposed for computer monitors as [[sRGB color space|sRGB]]. Both use the same color primaries and white point, but different transfer functions, as HDTV is intended for a dark living room while sRGB is intended for a brighter office environment.{{citation needed|date=January 2023}} The gamut of these spaces is limited, covering only 35.9% of the CIE 1931 gamut.<ref>{{cite web |last1=Yamashita |first1=Takayuki |last2=Nishida |first2=Yukihiro |last3=Emoto |first3=Masaki |last4=Ohmura |first4=Kohei |last5=Masaoka |first5=Kenichiro |last6=Masuda |first6=Hiroyasu |last7=Sugawara |first7=Masayuki |title=Super Hi-Vision as Next-Generation Television and Its Video Parameters |url=http://informationdisplay.org/IDArchive/2012/NovemberDecember/FrontlineTechnologySuperHiVisionasNextGen.aspx |website=Information Display|archive-url=https://web.archive.org/web/20180210024304/http://informationdisplay.org/IDArchive/2012/NovemberDecember/FrontlineTechnologySuperHiVisionasNextGen.aspx |archive-date=2018-02-10 }}</ref> While this allows the use of a limited bit depth without causing [[color banding]], and therefore reduces transmission bandwidth, it also prevents the encoding of deeply saturated colors that might be available in an alternate color spaces. Some RGB color spaces such as [[Adobe RGB color space|Adobe RGB]] and [[ProPhoto RGB color space|ProPhoto]] intended for the creation, rather than transmission, of images are designed with expanded gamuts to address this issue, however this does not mean the larger space has 'more colors". The numerical quantity of colors is related to bit depth and not the size or shape of the gamut. A large space with a low bit depth can be detrimental to the [[Color space#RGB density|gamut density]] and result in high <math> \Delta E </math> errors{{Explain|reason=Please define delta-E|date=January 2023}}.
[[High-definition television|HDTV]] uses the [[Rec. 709|BT.709]] color space, later repurposed for computer monitors as [[sRGB]]. Both use the same color primaries and white point, but different transfer functions, as HDTV is intended for a dark living room while sRGB is intended for a brighter office environment.{{Citation needed|date=January 2023}} The gamut of these spaces is limited, covering only 35.9% of the CIE 1931 gamut.<ref>{{cite web |last1=Yamashita |first1=Takayuki |last2=Nishida |first2=Yukihiro |last3=Emoto |first3=Masaki |last4=Ohmura |first4=Kohei |last5=Masaoka |first5=Kenichiro |last6=Masuda |first6=Hiroyasu |last7=Sugawara |first7=Masayuki |title=Super Hi-Vision as Next-Generation Television and Its Video Parameters |url=http://informationdisplay.org/IDArchive/2012/NovemberDecember/FrontlineTechnologySuperHiVisionasNextGen.aspx |website=Information Display|archive-url=https://web.archive.org/web/20180210024304/http://informationdisplay.org/IDArchive/2012/NovemberDecember/FrontlineTechnologySuperHiVisionasNextGen.aspx |archive-date=2018-02-10}}</ref> While this allows the use of a limited bit depth without causing [[Colour banding|color banding]], and therefore reduces transmission bandwidth, it also prevents the encoding of deeply saturated colors that might be available in an alternate color spaces. Some RGB color spaces such as [[Adobe RGB color space|Adobe RGB]] and [[ProPhoto RGB color space|ProPhoto]] intended for the creation, rather than transmission, of images are designed with expanded gamuts to address this issue, however this does not mean the larger space has 'more colors". The numerical quantity of colors is related to bit depth and not the size or shape of the gamut. A large space with a low bit depth can be detrimental to the [[Color space#RGB density|gamut density]] and result in high <math> \Delta E </math> errors.{{Explain|reason=Please define delta-E|date=January 2023}}


More recent color spaces such as [[Rec. 2020]] for UHD-TVs define an extremely large gamut covering 63.3% of the CIE 1931 space.<ref>{{cite web |last1=Baker |first1=Simon |title=The Pointer's Gamut - The Coverage of Real Surface Colors by RGB Color Spaces and Wide Gamut Displays |url=https://tftcentral.co.uk/articles/pointers_gamut |website=TFTCentral |access-date=13 January 2023 |language=en |date=19 February 2014}}</ref> This standard is not currently realisable with current LCD technology, and alternative architectures such as [[quantum dot]]<ref>{{cite journal |last1=Chen |first1=Haiwei |last2=He |first2=Juan |last3=Wu |first3=Shin-Tson |title=Recent Advances on Quantum-Dot-Enhanced Liquid-Crystal Displays |url=https://ieeexplore.ieee.org/document/7809081 |journal=IEEE Journal of Selected Topics in Quantum Electronics |pages=1–11 |doi=10.1109/JSTQE.2017.2649466 |date=September 2017|volume=23 |issue=5 |bibcode=2017IJSTQ..2349466C |s2cid=1400159 |url-access=subscription }}</ref> or [[OLED]]<ref>{{cite journal |last1=Huang |first1=Yuge |last2=Hsiang |first2=En-Lin |last3=Deng |first3=Ming-Yang |last4=Wu |first4=Shin-Tson |title=Mini-LED, Micro-LED and OLED displays: present status and future perspectives |journal=Light: Science & Applications |pages=105 |language=en |doi=10.1038/s41377-020-0341-9 |date=18 June 2020|volume=9 |issue=1 |pmid=32577221 |pmc=7303200 |bibcode=2020LSA.....9..105H |s2cid=235470310 }}</ref> based devices are currently{{When|date=March 2025}} in development.
More recent color spaces such as [[Rec. 2020]] for UHD-TVs define an extremely large gamut covering 63.3% of the CIE 1931 space.<ref>{{cite web |last1=Baker |first1=Simon |title=The Pointer's Gamut - The Coverage of Real Surface Colors by RGB Color Spaces and Wide Gamut Displays |url=https://tftcentral.co.uk/articles/pointers_gamut |website=TFTCentral |access-date=13 January 2023 |language=en |date=19 February 2014}}</ref> This standard is not currently realisable with current LCD technology, and alternative architectures such as [[quantum dot]]<ref>{{cite journal |last1=Chen |first1=Haiwei |last2=He |first2=Juan |last3=Wu |first3=Shin-Tson |title=Recent Advances on Quantum-Dot-Enhanced Liquid-Crystal Displays |journal=IEEE Journal of Selected Topics in Quantum Electronics |pages=1–11 |doi=10.1109/JSTQE.2017.2649466 |date=September 2017|volume=23 |issue=5 |bibcode=2017IJSTQ..2349466C |s2cid=1400159}}</ref> or [[OLED]]<ref>{{cite journal |last1=Huang |first1=Yuge |last2=Hsiang |first2=En-Lin |last3=Deng |first3=Ming-Yang |last4=Wu |first4=Shin-Tson |title=Mini-LED, Micro-LED and OLED displays: present status and future perspectives |journal=Light: Science & Applications |pages=105 |language=en |doi=10.1038/s41377-020-0341-9 |date=18 June 2020|volume=9 |issue=1 |pmid=32577221 |pmc=7303200 |bibcode=2020LSA.....9..105H |s2cid=235470310}}</ref> based devices are currently{{When|date=March 2025}} in development.


== Color space specifications employing the RGB color model ==
== Color space specifications employing the RGB color model ==
{| class="wikitable sortable"
{| class="wikitable sortable"
! rowspan="3" | Color space
! rowspan="3" | Reference Standard
! rowspan="3" | Primary Color Model
! rowspan="3" | Year
! rowspan="3" | [[Standard illuminant#White points of standard illuminants|White point]]
! colspan="6" | Color Primaries
! rowspan="2" | [[gamma correction|Display gamma]]
! colspan="5" | [[gamma correction|Transfer function parameters]]
|-
|-
!rowspan=3| Color space !!rowspan=3| Reference Standard
! colspan="2" | Red
! rowspan="3" |Primary Color Model!! rowspan="3" | Year
! colspan="2" | Green
!rowspan=3| [[Standard illuminant#White points of standard illuminants|White point]]
! colspan="2" | Blue
!colspan=6| Color Primaries
! rowspan="2" title="decoding gamma" | ''γ''
! rowspan="2" |[[Gamma correction|Display]]   
! title="offset 'a'" | α
[[Gamma correction|gamma]]
! title="linear-domain threshold" | β !! title="linear gain" | δ
! colspan="5" |[[gamma correction|Transfer function parameters]]
! title="transition point" | βδ
|-
|-
!colspan=2| Red !!colspan=2| Green !!colspan=2| Blue!! rowspan="2" title="decoding gamma" | ''γ''
! x<sub>ʀ</sub>
! title="offset 'a'" | α !! title="linear-domain threshold" | β !! title="linear gain" | δ !!title="transition point"| βδ
! y<sub>ʀ</sub>
! x<sub>ɢ</sub>
! y<sub>ɢ</sub>
! x<sub>ʙ</sub>
! y<sub>ʙ</sub>
! EOTF
! a + 1 !! K<sub>0</sub>/φ = E<sub>t</sub><!-- = δ^(γ/(α-γ)) -->
! φ<!-- = α^γ*(γ-1)^(γ-1) / (a^(γ-1)*γ^γ) --> !! K<sub>0</sub><!-- = a/(γ-1) -->
|-
|-
! x<sub>ʀ</sub> !! y<sub>ʀ</sub> !! x<sub>ɢ</sub> !! y<sub>ɢ</sub> !! x<sub>ʙ</sub> !! y<sub>ʙ</sub>
! [[NTSC-J]]
!EOTF
| ''Based on NTSC (M)''
! a + 1 !! K<sub>0</sub>/φ = E<sub>t</sub><!--= δ^(γ/(α-γ))--> !! φ<!--= α^γ*(γ-1)^(γ-1) / (a^(γ-1)*γ^γ)--> !! K<sub>0</sub><!--= a/(γ-1)-->
| Y′IQ, YCbCr
|-
| 1987
![[NTSC-J]]
| [[Standard illuminant#Illuminant series D|D93]]
|''Based on NTSC(M)''
| rowspan="2" | 0.63
|Y′IQ, YCbCr
| rowspan="3" | 0.34
|1987
| rowspan="2" | 0.31
|[[Standard illuminant#Illuminant series D|D93]]
| rowspan="3" | 0.595
| rowspan="2" |0.63
| rowspan="3" | 0.155
| rowspan="3" |0.34
| rowspan="3" | 0.07
| rowspan="2" |0.31
| rowspan="2" | Curved
| rowspan="3" |0.595
| rowspan="3" |0.155
| rowspan="3" |0.07
| rowspan="2" |Curved
|
|
| colspan="4" |
| colspan="4" |
|-
|-
![[NTSC]], [[Multiple sub-Nyquist sampling encoding|MUSE]]
! [[NTSC]], [[Multiple sub-Nyquist sampling encoding|MUSE]]
|SMPTE RP 145 ([[SMPTE C|C]]), 170M, 240M
| SMPTE RP 145 ([[SMPTE C|C]]), 170M, 240M
|Y′IQ, YPbPr, YCbCr
| Y′IQ, YPbPr, YCbCr
|1987
| 1987
| rowspan="8" |[[Illuminant D65|D65]]
| rowspan="8" | [[Illuminant D65|D65]]
|{{sfrac|20|9}}
| {{sfrac|20|9}}
|1.1115
| 1.1115
|0.0057
| 0.0057
|4
| 4
|0.0228
| 0.0228
|-
|-
!{{visible anchor|Apple RGB}}
! {{visible anchor|Apple RGB}}
|''(Apple Computer)''
| ''(Apple Computer)''
|RGB
| RGB
|
|
|0.625
| 0.625
|0.28
| 0.28
|1.8
| 1.8
|
|
| colspan="4" rowspan="2" |
| colspan="4" rowspan="2" |
|-
|-
![[PAL]] / [[SECAM]]
! [[PAL]] / [[SECAM]]
|[[EBU]] 3213-E, [[Rec. 601|BT.470/601 (B/G)]]
| [[EBU]] 3213-E, [[Rec. 601|BT.470/601 (B/G)]]
|Y′UV, YDbDr, YCbCr
| Y′UV, YDbDr, YCbCr
|1970
| 1970
| rowspan="5" |0.64
| rowspan="5" | 0.64
| rowspan="9" |0.33
| rowspan="9" | 0.33
|0.29
| 0.29
| rowspan="4" |0.60
| rowspan="4" | 0.60
| rowspan="5" |0.15
| rowspan="5" | 0.15
| rowspan="5" |0.06
| rowspan="5" | 0.06
|Curved
| Curved
|{{sfrac|14|5}}
| {{sfrac|14|5}}
|-
|-
! [[sRGB]]
! [[sRGB]]
| IEC 61966-2-1  
| IEC 61966-2-1
|RGB|| 1996, 1999
| RGB
| rowspan="3" |0.30
| 1996, 1999
| rowspan="2" |2.2|| rowspan="2" title="2.4" | {{sfrac|12|5}}  
| rowspan="3" | 0.30
| rowspan="2" | 1.055 || rowspan="2" title="0.0031308049535" | 0.0031308 || rowspan="2" title="12.920020442059" | 12.92 || rowspan="2" title="0.040449936" | 0.04045
| rowspan="2" | 2.2
| rowspan="2" title="2.4" | {{sfrac|12|5}}
| rowspan="2" | 1.055
| rowspan="2" title="0.0031308049535" | 0.0031308
| rowspan="2" title="12.920020442059" | 12.92
| rowspan="2" title="0.040449936" | 0.04045
|-
|-
![[scRGB]]
! [[scRGB]]
|IEC 61966-2-2<!-- IEC 61966-2-4 xvYCC -->
| IEC 61966-2-2<!-- IEC 61966-2-4 xvYCC -->
|
|
|2003
| 2003
|-
|-
! [[High-definition television|HDTV]]
! [[High-definition television|HDTV]]
| [[ITU-R]] [[Rec. 709|BT.709]]
| [[ITU-R]] [[Rec. 709|BT.709]]
|YCbCr|| 1999
| YCbCr
|Curved|| title="2.(2)" | {{sfrac|20|9}}  
| 1999
| 1.099 || 0.004 || 4.5 || 0.018
| Curved
| title="2.(2)" | {{sfrac|20|9}}
| 1.099
| 0.004
| 4.5
| 0.018
|-
|-
! [[Adobe RGB color space|Adobe RGB]]
! [[Adobe RGB color space|Adobe RGB]]
| ''(Adobe)''
| ''(Adobe)''
|RGB|| 1998
| RGB
| rowspan="5" | 0.21 || rowspan="5" | 0.71
| 1998
|2.2|| title="≈ 2.2" | {{sfrac|563|256}}  
| rowspan="5" | 0.21
| rowspan="5" | 0.71
| 2.2
| title="≈ 2.2" | {{sfrac|563|256}}
| colspan="4" rowspan="4" |
| colspan="4" rowspan="4" |
|-
|-
![[Multiplexed Analogue Components|M.A.C]].
! [[Multiplexed Analogue Components|M.A.C]].
|ITU-R BO.650-2<ref>{{Cite web |title=RECOMMENDATION ITU-R BO.650-2 *,** {{!}} Standards for conventional television systems for satellite broadcasting in the channels defined by Appendix 30 of the Radio Regulations |url=https://extranet.itu.int/brdocsearch/R-REC/R-REC-BO/R-REC-BO.650/R-REC-BO.650-2-199203-I/R-REC-BO.650-2-199203-I!!PDF-E.pdf#page=18 |website=}}</ref>
| ITU-R BO.650-2<ref>{{cite web |title=RECOMMENDATION ITU-R BO.650-2 *,** {{!}} Standards for conventional television systems for satellite broadcasting in the channels defined by Appendix 30 of the Radio Regulations |url=https://extranet.itu.int/brdocsearch/R-REC/R-REC-BO/R-REC-BO.650/R-REC-BO.650-2-199203-I/R-REC-BO.650-2-199203-I!!PDF-E.pdf#page=18}}</ref>
|YPbPr
| YPbPr
|1985
| 1985
| rowspan="4" |0.67
| rowspan="4" | 0.67
| rowspan="4" |0.14
| rowspan="4" | 0.14
| rowspan="4" |0.08
| rowspan="4" | 0.08
|2.8
| 2.8
|
|
|-
|-
! [[NTSC#Colorimetry|NTSC-FCC]]
! [[NTSC#Colorimetry|NTSC-FCC]]
| [[Rec. 601|ITU-R BT.470/601 (M)]]
| [[Rec. 601|ITU-R BT.470/601 (M)]]
|Y′IQ, YCbCr|| 1953
| Y′IQ, YCbCr
| 1953
| rowspan="2" title="(0.3101, 0.3162)" | [[Standard illuminant#Illuminants B and C|C]]
| rowspan="2" title="(0.3101, 0.3162)" | [[Standard illuminant#Illuminants B and C|C]]
| rowspan="2" | 2.2<ref>47 CFR § 73.682 (20) (iv)</ref>
| rowspan="2" | 2.2<ref>47 CFR § 73.682 (20) (iv)</ref>
| title="2.2" | {{sfrac|11|5}}  
| title="2.2" | {{sfrac|11|5}}
|-
|-
![[PAL-M]]
! [[PAL-M]]
|ITU-R BT.470-6<ref>{{Cite web |title=Recommendation ITU-R BT.470-6 {{!}} Conventional Television Systems |url=https://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.470-6-199811-S!!PDF-E.pdf#page=2}}</ref>
| ITU-R BT.470-6<ref>{{cite web |title=Recommendation ITU-R BT.470-6 {{!}} Conventional Television Systems |url=https://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.470-6-199811-S!!PDF-E.pdf#page=2}}</ref>
|Y′UV, YCbCr
| Y′UV, YCbCr
|1972
| 1972
|
|
|-
|-
! [[eciRGB]]
! [[eciRGB]]
| ISO 22028-4  
| ISO 22028-4
| || 2008, 2012
|
| title="(0.34567, 0.35850), ISO 22028: (0.3457, 0.3585) " | [[Standard illuminant#Illuminant series D|D50]]
| 2008, 2012
|1.8|| 3  
| title="(0.34567, 0.35850), ISO 22028: (0.3457, 0.3585)" | [[Standard illuminant#Illuminant series D|D50]]
| 1.16 || 0.008856 || 9.033 || 0.08
| 1.8
| 3
| 1.16
| 0.008856
| 9.033
| 0.08
|-
|-
![[DCI-P3]]
! [[DCI-P3]]
|SMPTE RP 431-2
| SMPTE RP 431-2
|YCbCr
| YCbCr
|2011
| 2011
|6300K
| 6300K
| rowspan="2" |0.68
| rowspan="2" | 0.68
| rowspan="2" |0.32
| rowspan="2" | 0.32
| rowspan="2" |0.265
| rowspan="2" | 0.265
| rowspan="2" |0.69
| rowspan="2" | 0.69
| rowspan="2" |0.15
| rowspan="2" | 0.15
| rowspan="2" |0.06
| rowspan="2" | 0.06
|2.6
| 2.6
|{{sfrac|13|5}}
| {{sfrac|13|5}}
| colspan="4" |
| colspan="4" |
|-
|-
![[Display P3]]
! [[DCI-P3#Display P3|Display P3]]
|SMPTE EG 432-1
| SMPTE EG 432-1
|RGB
| RGB
|2010
| 2010
| rowspan="2" |D65
| rowspan="2" | D65
|~2.2
| ~2.2
|{{sfrac|12|5}}
| {{sfrac|12|5}}
| rowspan="1" |1.055
| rowspan="1" | 1.055
| rowspan="1" |0.0031308
| rowspan="1" | 0.0031308
| rowspan="1" |12.92
| rowspan="1" | 12.92
| rowspan="1" |0.04045
| rowspan="1" | 0.04045
|-
|-
![[Ultra-high-definition television|UHDTV]]
! [[Ultra-high-definition television|UHDTV]]
|[[ITU-R]] [[Rec. 2020|BT.2020]], [[Rec. 2100|BT.2100]]
| [[ITU-R]] [[Rec. 2020|BT.2020]], [[Rec. 2100|BT.2100]]
|YCbCr
| YCbCr
|2012, 2016
| 2012, 2016
|0.708
| 0.708
|0.292
| 0.292
|0.170
| 0.170
|0.797
| 0.797
|0.131
| 0.131
|0.046
| 0.046
|Curved
| Curved
|
|
|1.0993
| 1.0993
|0.018054
| 0.018054
|4.5
| 4.5
|0.081243
| 0.081243
|-
|-
! [[Wide-gamut RGB color space|Wide Gamut]]
! [[Wide-gamut RGB color space|Wide Gamut]]
| ''(Adobe)''
| ''(Adobe)''
|RGB||
| RGB
| rowspan="3" title="(0.34567, 0.35850), ISO 22028: (0.3457, 0.3585) " | [[Standard illuminant#Illuminant series D|D50]]
|
| title="700 nm" | 0.7347 || 0.2653 || title="525 nm" | 0.1152 || 0.8264 || title="450 nm" | 0.1566 || 0.0177
| rowspan="3" title="(0.34567, 0.35850), ISO 22028: (0.3457, 0.3585)" | [[Standard illuminant#Illuminant series D|D50]]
|2.2|| title="= 2.19921875" | {{sfrac|563|256}}  
| title="700 nm" | 0.7347
| 0.2653
| title="525 nm" | 0.1152
| 0.8264
| title="450 nm" | 0.1566
| 0.0177
| 2.2
| title="= 2.19921875" | {{sfrac|563|256}}
| colspan="4" |
| colspan="4" |
|-
|-
! RIMM  
! RIMM
| ISO 22028-3  
| ISO 22028-3
| || 2006, 2012
|
| 0.7347 || 0.2653 || 0.1596 || 0.8404 || 0.0366 || 0.0001
| 2006, 2012
|2.222|| title="2.(2)" | {{sfrac|20|9}}  
| 0.7347
|| 1.099|| 0.0018 || 5.5 || 0.099
| 0.2653
| 0.1596
| 0.8404
| 0.0366
| 0.0001
| 2.222
| title="2.(2)" | {{sfrac|20|9}}
| 1.099
| 0.0018
| 5.5
| 0.099
|-
|-
! [[ProPhoto RGB color space|ProPhoto (ROMM)]]  
! [[ProPhoto RGB color space|ProPhoto (ROMM)]]  
| ISO 22028-2  
| ISO 22028-2  
| || 2006, 2013
|
| 0.734699 || 0.265301 || 0.159597 || 0.840403 || 0.036598 || 000105
| 2006, 2013
|1.8|| title="1.8" | {{sfrac|9|5}}  
| 0.734699
| 1 || title="1/512" | 0.001953125 || 16 || 0.031248
| 0.265301
| 0.159597
| 0.840403
| 0.036598
| 000105
| 1.8
| title="1.8" | {{sfrac|9|5}}
| 1
| title="1/512" | 0.001953125
| 16
| 0.031248
|-
|-
! [[CIE 1931 color space#CIE RGB color space|CIE RGB]] .
! [[CIE 1931 color space#CIE RGB color space|CIE RGB]]
| rowspan="2" |[[CIE 1931 color space]] <ref>{{cite web |last=Harley |first=Nicola |date=10 May 2017 |title=Color picker from image |url=https://html-color-codes.info/colors-from-image/ |url-access=subscription |url-status=live |archive-url=https://web.archive.org/web/20250609164950/https://shotvu.com/ |archive-date=9 Jun 2025 |publisher=The Telegraph |location=}}{{cbignore}}</ref>
| rowspan="2" | [[CIE 1931 color space]]
|
|
| rowspan="2" | 1931
| rowspan="2" | 1931
| rowspan="2" title="(1/3, 1/3)" | [[Standard illuminant#Illuminant E|E]]
| rowspan="2" title="(1/3, 1/3)" | [[Standard illuminant#Illuminant E|E]]
| 0.73474284 || 0.26525716 || 0.27377903 || 0.7174777 || 0.16655563 || 0.00891073
| 0.73474284
| 0.26525716
| 0.27377903
| 0.7174777
| 0.16655563
| 0.00891073
|
|
|
|
| colspan="4" rowspan="2" |
| colspan="4" rowspan="2" |
|- title="mot RGB!"
|- title="mot RGB!"
! [[CIE 1931 color space|CIE XYZ]]
! [[CIE 1931 color space|CIE XYZ]]
!
!
| 1 || 0 || 0 || 1 || 0 || 0
| 1
| || 1  
| 0
| 0
| 1
| 0
| 0
|
| 1  
|}
|}
<!--JEDEC P22 / EIA397 (JC-22.1)  
 
FFmpeg -color_primaries jedec-p22
<!-- JEDEC P22 / EIA397 (JC-22.1) FFmpeg -color_primaries jedec-p22
| D65 || 0.63 || 0.34 || 0.295 || 0.605 || 0.155 || 0.077 -->The [[CIE 1931 color space]] standard defines both the CIE RGB space, which is a color space with monochromatic [[Primary color|primaries]], and the CIE XYZ color space, which is functionally similar to a linear RGB color space, however the primaries are not physically realizable, thus are not described as red, green, and blue.
| D65
| 0.63
| 0.34
| 0.295
| 0.605
| 0.155
| 0.077 -->
The [[CIE 1931 color space]] standard defines both the CIE RGB space, which is a color space with monochromatic [[Primary color|primaries]], and the CIE XYZ color space, which is functionally similar to a linear RGB color space, however the primaries are not physically realizable, thus are not described as red, green, and blue.


M.A.C. is not to be confused with MacOS. Here, M.A.C.refers to [[Multiplexed Analogue Components]].
M.A.C. is not to be confused with MacOS. Here, M.A.C.refers to [[Multiplexed Analogue Components]].


==See also==
== See also ==
 
* [[CIELUV|CIELUV color space]]
*[[CIELUV color space]]
* [[Web colors]]
*[[Web colors]]
* [[RGB color model]]
*[[RGB color model]]
* [[RGBA color model]]
*[[RGBA color model]]


==References==
== References ==
{{Reflist}}
{{reflist}}


==External links==
== External links ==
* [https://codenameart.com/downloads/free-rgb-color-chart/ RGB Color Chart.]
* [https://codenameart.com/downloads/free-rgb-color-chart/ RGB Color Chart.]
* {{cite web|publisher=International Color Consortium (ICC) |url=https://www.color.org/chardata/rgb/rgb_registry.xalter |title=Three component color encoding registry |access-date=2022-02-11}}
* {{cite web |publisher=International Color Consortium (ICC) |url=https://www.color.org/chardata/rgb/rgb_registry.xalter |title=Three component color encoding registry |access-date=2022-02-11}}
*{{cite web|author=Susstrunk, Buckley and Swen|url=http://infoscience.epfl.ch/getfile.py?mode=best&recid=34089|title=Standard RGB Color Spaces|format=PDF|access-date=November 18, 2005}}
* {{cite web |author=Susstrunk, Buckley and Swen |url=http://infoscience.epfl.ch/getfile.py?mode=best&recid=34089 |title=Standard RGB Color Spaces |format=PDF |access-date=November 18, 2005 |archive-date=February 17, 2007 |archive-url=https://web.archive.org/web/20070217040139/http://infoscience.epfl.ch/getfile.py?mode=best&recid=34089 |url-status=dead}}
*{{cite web|author=Lindbloom, Bruce|url=http://www.brucelindbloom.com/index.html?WorkingSpaceInfo.html|title=RGB Working Space Information|access-date=November 18, 2005}}
* {{cite web |author=Lindbloom, Bruce |url=http://www.brucelindbloom.com/index.html?WorkingSpaceInfo.html |title=RGB Working Space Information |access-date=November 18, 2005}}
*{{cite web|author=Colantoni, Philippe|url=http://www.couleur.org/index.php?page=rgbcube|title=RGB cube transformation in different color spaces|url-status=dead|archive-url=https://web.archive.org/web/20080505081130/http://www.couleur.org/index.php?page=rgbcube|archive-date=2008-05-05}}
* {{cite web |author=Colantoni, Philippe |url=http://www.couleur.org/index.php?page=rgbcube |title=RGB cube transformation in different color spaces |url-status=dead |archive-url=https://web.archive.org/web/20080505081130/http://www.couleur.org/index.php?page=rgbcube |archive-date=2008-05-05}}


{{Color space}}
{{Color space}}


[[Category:Color space]]
[[Category:Color space]]

Latest revision as of 14:41, 5 September 2025

Template:Short description Template:More citations needed

File:CIE1931xy gamut comparison.svg
1931 CIE chromaticity diagram showing some RGB color spaces as defined by their chromaticity triangles

RGB color spaces are a category of additive colorimetric color spaces[1] specifying part of its absolute color space definition using the RGB color model.[2]

RGB color spaces are commonly found describing the mapping of the RGB color model to human perceivable color, but some RGB color spaces use imaginary (non-real-world) primaries and thus can not be displayed directly.

Like any color space, while the specifications in this category use the RGB color model to describe their space, it is not mandatory to use that model to signal pixel color values. Broadcast TV color spaces like NTSC, PAL, Rec. 709, Rec. 2020 additionally describe a translation from RGB to YCbCr and that is how they are usually signalled for transmission, but an image can be stored as either RGB or YCbCr. This demonstrates using the singular term "RGB color space" can be misleading, since a chosen color space or signalled colour can be described by any appropriate color model. However the singular can be seen in specifications where storage signalled as RGB is its intended use.

Definition

File:RGB Cube Show lowgamma cutout b.png
RGB cube

The normal human eye contains three types of color-sensitive cone cells. Each cell is responsive to light of either long, medium, or short wavelengths, which we generally categorize as red, green, and blue. Taken together, the responses of these cone cells are called the Tristimulus values, and the combination of their responses is processed into the psychological effect of color vision.

RGB use in color space definitions employ primaries (and often a white point) based on the RGB color model, to map to real world color. Applying Grassmann's law of light additivity, the range of colors that can be produced are those enclosed within the triangle on the chromaticity diagram defined using the primaries as vertices.[3]

The primary colors are usually mapped to xyY chromaticity coordinates, though the uʹ,vʹ coordinates from the UCS chromaticity diagram may be used. Both xyY and uʹ,vʹ are derived from the CIE 1931 color space, a device independent space also known as XYZ which covers the full gamut of human-perceptible colors visible to the CIE 2° standard observer.

Applications

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File:1Mcolors.png
One million colors in RGB space, visible in full-size image

RGB color spaces are well-suited to describing the electronic display of color, such as computer monitors and color television. These devices often reproduce colours using an array of red, green, and blue phosphors agitated by a cathode-ray tube (CRT), or an array of red, green, and blue LCDs lit by a backlight, and are therefore naturally described by an additive color model with RGB primaries.

Early examples of RGB color spaces came with the adoption of the NTSC color television standard in 1953 across North America, followed by PAL and SECAM covering the rest of the world. These early RGB spaces were defined in part by the phosphor used by CRTs in use at the time, and the gamma of the electron beam. While these color spaces reproduced the intended colors using additive red, green, and blue primaries, the broadcast signal itself was encoded from RGB components to a composite signal such as YIQ, and decoded back by the receiver into RGB signals for display.

HDTV uses the BT.709 color space, later repurposed for computer monitors as sRGB. Both use the same color primaries and white point, but different transfer functions, as HDTV is intended for a dark living room while sRGB is intended for a brighter office environment.Script error: No such module "Unsubst". The gamut of these spaces is limited, covering only 35.9% of the CIE 1931 gamut.[4] While this allows the use of a limited bit depth without causing color banding, and therefore reduces transmission bandwidth, it also prevents the encoding of deeply saturated colors that might be available in an alternate color spaces. Some RGB color spaces such as Adobe RGB and ProPhoto intended for the creation, rather than transmission, of images are designed with expanded gamuts to address this issue, however this does not mean the larger space has 'more colors". The numerical quantity of colors is related to bit depth and not the size or shape of the gamut. A large space with a low bit depth can be detrimental to the gamut density and result in high ΔE errors.Template:Explain

More recent color spaces such as Rec. 2020 for UHD-TVs define an extremely large gamut covering 63.3% of the CIE 1931 space.[5] This standard is not currently realisable with current LCD technology, and alternative architectures such as quantum dot[6] or OLED[7] based devices are currentlyTemplate:When in development.

Color space specifications employing the RGB color model

Color space Reference Standard Primary Color Model Year White point Color Primaries Display gamma Transfer function parameters
Red Green Blue γ α β δ βδ
xʀ yʀ xɢ yɢ xʙ yʙ EOTF a + 1 K0/φ = Et φ K0
NTSC-J Based on NTSC (M) Y′IQ, YCbCr 1987 D93 0.63 0.34 0.31 0.595 0.155 0.07 Curved
NTSC, MUSE SMPTE RP 145 (C), 170M, 240M Y′IQ, YPbPr, YCbCr 1987 D65 Template:Sfrac 1.1115 0.0057 4 0.0228
Template:Visible anchor (Apple Computer) RGB 0.625 0.28 1.8
PAL / SECAM EBU 3213-E, BT.470/601 (B/G) Y′UV, YDbDr, YCbCr 1970 0.64 0.33 0.29 0.60 0.15 0.06 Curved Template:Sfrac
sRGB IEC 61966-2-1 RGB 1996, 1999 0.30 2.2 Template:Sfrac 1.055 0.0031308 12.92 0.04045
scRGB IEC 61966-2-2 2003
HDTV ITU-R BT.709 YCbCr 1999 Curved Template:Sfrac 1.099 0.004 4.5 0.018
Adobe RGB (Adobe) RGB 1998 0.21 0.71 2.2 Template:Sfrac
M.A.C. ITU-R BO.650-2[8] YPbPr 1985 0.67 0.14 0.08 2.8
NTSC-FCC ITU-R BT.470/601 (M) Y′IQ, YCbCr 1953 C 2.2[9] Template:Sfrac
PAL-M ITU-R BT.470-6[10] Y′UV, YCbCr 1972
eciRGB ISO 22028-4 2008, 2012 D50 1.8 3 1.16 0.008856 9.033 0.08
DCI-P3 SMPTE RP 431-2 YCbCr 2011 6300K 0.68 0.32 0.265 0.69 0.15 0.06 2.6 Template:Sfrac
Display P3 SMPTE EG 432-1 RGB 2010 D65 ~2.2 Template:Sfrac 1.055 0.0031308 12.92 0.04045
UHDTV ITU-R BT.2020, BT.2100 YCbCr 2012, 2016 0.708 0.292 0.170 0.797 0.131 0.046 Curved 1.0993 0.018054 4.5 0.081243
Wide Gamut (Adobe) RGB D50 0.7347 0.2653 0.1152 0.8264 0.1566 0.0177 2.2 Template:Sfrac
RIMM ISO 22028-3 2006, 2012 0.7347 0.2653 0.1596 0.8404 0.0366 0.0001 2.222 Template:Sfrac 1.099 0.0018 5.5 0.099
ProPhoto (ROMM) ISO 22028-2 2006, 2013 0.734699 0.265301 0.159597 0.840403 0.036598 000105 1.8 Template:Sfrac 1 0.001953125 16 0.031248
CIE RGB CIE 1931 color space 1931 E 0.73474284 0.26525716 0.27377903 0.7174777 0.16655563 0.00891073
CIE XYZ 1 0 0 1 0 0 1

The CIE 1931 color space standard defines both the CIE RGB space, which is a color space with monochromatic primaries, and the CIE XYZ color space, which is functionally similar to a linear RGB color space, however the primaries are not physically realizable, thus are not described as red, green, and blue.

M.A.C. is not to be confused with MacOS. Here, M.A.C.refers to Multiplexed Analogue Components.

See also

References

Template:Reflist

External links

  • RGB Color Chart.
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Template:Color space

  1. ↑ Script error: No such module "citation/CS1".
  2. ↑ Script error: No such module "citation/CS1".
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  5. ↑ Script error: No such module "citation/CS1".
  6. ↑ Script error: No such module "Citation/CS1".
  7. ↑ Script error: No such module "Citation/CS1".
  8. ↑ Script error: No such module "citation/CS1".
  9. ↑ 47 CFR § 73.682 (20) (iv)
  10. ↑ Script error: No such module "citation/CS1".
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