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50% CIELAB lightness
(Y = 18.4%)

In photography, painting, and other visual arts, middle gray or middle grey is a tone that is perceptually about halfway between black and white on a lightness scale;^[1] in photography and printing, it is typically defined as 18% reflectance in visible light.^[2]^[3]

Light meters, cameras, and pictures are often calibrated using an 18% gray card^[4]^[5]^[6] or a color reference card such as a ColorChecker.^[7]^[8]^[9] On the assumption that 18% is similar to the average reflectance of a scene, a gray card can be used to estimate the required exposure of the film.^[5]

History

Following the Weber–Fechner law, at the start of the 20th century human lightness perception was assumed to be logarithmic. In 1903, The New International Encyclopædia illustrated this concept by stating that given a black and white with a luminance ratio of 1:60 (　 : 　), the geometric mean had to be used to find the middle gray.^[10] That is equivalent to a relative luminance of 12.9% (　).

When Albert Henry Munsell was developing his color system, he tried to ascertain the relation between luminance and perceived lightness. As early as 1906, he wrote: 'Should we use logarithmic curve or curve of squares?'^[11] In 1920 Priest, Gibson, and McNicholas showed using both a König-Martens spectrophotometer and an apparatus designed by Gibson where the outputs of two photocells are balanced^[12] that the shades in Munsell's 1915 atlas followed a square root curve, which was later confirmed by extensive experiments.^[13]^[14] In Munsell's system, the shades of neutral gray were labelled N¹ to N⁹, with N⁵ in the middle and 0 and 10 denoting the unachievable ideal black and perfect white.^[15]

In 1933, Alexander Ector Orr Munsell (Albert Henry Munsell's son) found "that a series of neutral reflecting surfaces whose reflectances are...18.0...and 100.0 percent...form for the average observer a series of equal differences in value."^[16]

From the 1930s onward various lightness curves were proposed, but halfway through the 20th century, the proposals settled on cube-root-based curves. In 1976 the International Commission on Illumination defined the CIELAB color space,^[17] an extension of which would become the standard for the coming decades in a variety of applications.^[18]^[19] Following research in the 80s and 90s, more and more advanced models of color vision were developed, the first major step being CIECAM97s; see Lightness § 1933 for details.

Table of middle grays

Below are various "middle" grays based on various criteria.

The shades in the rightmost column will only be correct if viewed on a calibrated monitor.

Note that LCD screens, even when correctly calibrated, often have a brightness that varies considerably depending on the viewing angle.

Middle gray as defined by	Year	CIEXYZ relative luminance (Y)
Geomean of 60:1	1903	12.91%
Munsell, Sloan & Godlove	1933	18%
CIELAB	1976	18.42%
sRGB	1996	21.40%
Munsell's original N⁵	1906	25.00%
NCS S 5000-N	1964	26%
Mac, pre-OS X 10.6	1984	≈ 30%
CIECAM02 lightness	2002	*
CIECAM97s lightness	1997	*
50% Luminance	1931	50.00%

Quarter luminance list (typical monitor calibrated to 2.2 gamma, 50% luminance gray has RGB hex 0xBA value, which is 0.5^(1/2.2)*255)

Middle gray as defined by	Year	CIEXYZ relative luminance
100% Luminance	1931	100%
75% Luminance	1931	75%
50% Luminance	1931	50%
25% Luminance	1931	25%
0% Luminance	1931	0%

* Context-dependent; an estimate is displayed here taking the environment where it appears in the article into account and assuming a neutrally lit surround of 200 cd/m².

References

^ Stephen Quiller (1999). Painter's Guide to Color: Includes the New Quiller Color Wheel. Watson-Guptill. ISBN 0-8230-3913-7.
^ Blain Brown (2002). Cinematography: Theory and Practice : Imagemaking for Cinematographers, Directors, and Videographers. Focal Press. ISBN 0-240-80500-3.
^ Woods, Mark. How to Effectively Use the Gray Card Archived 2014-11-29 at the Wayback Machine. cameraguild.com
^ Steven Barclay (1999). The Motion Picture Image: From Film to Digital. Focal Press. ISBN 0-240-80390-6.
^ ^a ^b Film and Its Techniques by Raymond Spottiswoode
^ Gevaert Manual of Photography, ed. A.H.S. Craeybeckx
^ C. S. McCamy, H. Marcus, and J. G. Davidson (1976). "A Color-Rendition Chart". Journal of Applied Photographic Engineering 2(3). 95–99.
^ Shoptalk: a new tool for checking color photography by Norman Goldberg
^ How to Photograph Landscapes & Scenic Views by David Brooks
^ Daniel Coit Gilman; Harry Thurston Peck & Frank Moore Colby (1903). The New International Encyclopædia. Dodd, Mead and Company.
^ Kuehni, Rolf G. (February 2002). "The early development of the Munsell system". Color Research & Application. 27 (1): 20–27. doi:10.1002/col.10002.
^ First the photocells are illuminated by lamps and their outputs are balanced without the sample present; then the sample is placed at one cell and the lamp illuminating the other cell is moved further away until the outputs rebalance. For a more detailed description see K.S. Gibson, Photoelectric spectrophotometry using the null method.
^ Priest, Irwin G.; Gibson, K.S.; McNicholas, H.J. (September 1920). "An examination of the Munsell color system. I: Spectral and total reflection and the Munsell scale of Value". Technical Paper 167 (3). United States Bureau of Standards: 27.
^ Munsell AEO, Sloan LL, Godlove IH. Neutral value scales I, Munsell neutral value scale. J Opt Soc Am 1933;23:394 – 401
^ Priest, Irwin G.; Gibson, K.S.; McNicholas, H.J. (September 1920). "An examination of the Munsell color system. I: Spectral and total reflection and the Munsell scale of Value". Technical Paper 167 (3). United States Bureau of Standards: 27.
^ Munsell AEO, Sloan LL, Godlove IH. Neutral value scales I, Munsell neutral value scale. J Opt Soc Am 1933;23:394 – 401
^ CIE Colorimetry–Part 4: 1976 L* a* b* Colour Space
^ H. Pauli, Proposed extension of the CIE recommendation on "Uniform color spaces, color difference equations, and metric color terms"
^ Kenichiro Masaoka, Fu Jiang, Mark D. Fairchild & Rodney L. Heckaman, Analysis of color volume of multi-chromatic displays using gamut rings

[1] Stephen Quiller (1999). Painter's Guide to Color: Includes the New Quiller Color Wheel. Watson-Guptill. ISBN 0-8230-3913-7.

[2] Blain Brown (2002). Cinematography: Theory and Practice : Imagemaking for Cinematographers, Directors, and Videographers. Focal Press. ISBN 0-240-80500-3.

[3] Woods, Mark. How to Effectively Use the Gray Card Archived 2014-11-29 at the Wayback Machine. cameraguild.com

[4] Steven Barclay (1999). The Motion Picture Image: From Film to Digital. Focal Press. ISBN 0-240-80390-6.

[Spottiswoode-5] Film and Its Techniques by Raymond Spottiswoode

[6] Gevaert Manual of Photography, ed. A.H.S. Craeybeckx

[7] C. S. McCamy, H. Marcus, and J. G. Davidson (1976). "A Color-Rendition Chart". Journal of Applied Photographic Engineering 2(3). 95–99.

[8] Shoptalk: a new tool for checking color photography by Norman Goldberg

[9] How to Photograph Landscapes & Scenic Views by David Brooks

[10] Daniel Coit Gilman; Harry Thurston Peck & Frank Moore Colby (1903). The New International Encyclopædia. Dodd, Mead and Company.

[11] Kuehni, Rolf G. (February 2002). "The early development of the Munsell system". Color Research & Application. 27 (1): 20–27. doi:10.1002/col.10002.

[12] First the photocells are illuminated by lamps and their outputs are balanced without the sample present; then the sample is placed at one cell and the lamp illuminating the other cell is moved further away until the outputs rebalance. For a more detailed description see K.S. Gibson, Photoelectric spectrophotometry using the null method.

[13] Priest, Irwin G.; Gibson, K.S.; McNicholas, H.J. (September 1920). "An examination of the Munsell color system. I: Spectral and total reflection and the Munsell scale of Value". Technical Paper 167 (3). United States Bureau of Standards: 27.

[14] Munsell AEO, Sloan LL, Godlove IH. Neutral value scales I, Munsell neutral value scale. J Opt Soc Am 1933;23:394 – 401

[15] Priest, Irwin G.; Gibson, K.S.; McNicholas, H.J. (September 1920). "An examination of the Munsell color system. I: Spectral and total reflection and the Munsell scale of Value". Technical Paper 167 (3). United States Bureau of Standards: 27.

[16] Munsell AEO, Sloan LL, Godlove IH. Neutral value scales I, Munsell neutral value scale. J Opt Soc Am 1933;23:394 – 401

[17] CIE Colorimetry–Part 4: 1976 L* a* b* Colour Space

[18] H. Pauli, Proposed extension of the CIE recommendation on "Uniform color spaces, color difference equations, and metric color terms"

[19] Kenichiro Masaoka, Fu Jiang, Mark D. Fairchild & Rodney L. Heckaman, Analysis of color volume of multi-chromatic displays using gamut rings

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+{{Short description|Shade of the color gray}}{{Cleanup rewrite|date=June 2022|there are many articles on gray, this one either needs to be cleaned up and made unique and useful, or deleted, or merged. It does not comply with Wikipedia's quality standards.|entire article}}
-{{Short description|Shade of the color gray}}{{Multiple issues|
-{{Cleanup rewrite|date=June 2022|There are many articles on grey, this one either needs to be cleaned up and made unique and useful, or deleted, or merged. It does not comply with Wikipedia's quality standards.|entire article}}{{Copy edit|for=Part of it reads like a how-to guide|date=September 2022}}
-{{External links|date=September 2022}}
-}}
 <div class="thumb tright"><div class=thumbinner style=width:12em><div style=background:white;position:relative;height:9em><div style=background:black;position:absolute;width:50%;height:100%></div><div style=background:rgba({{loop|3|{{#expr:255*(1.055*((50+16)/116)^(3/2.4)-0.055)}},}}1);position:absolute;left:25%;top:25%;width:50%;height:50%></div></div><div class=thumbcaption style=text-align:center>50% [[CIELAB]] lightness<br />([[Tristimulus colorimeter|Y]] = {{#expr:((50+16)/116)^3*100round1}}%)</div></div></div>
 In [[photography]], [[painting]], and other visual arts, '''middle gray''' or '''middle grey''' is a tone that is perceptually about halfway between black and white on a [[lightness (color)|lightness]] scale;<ref>{{cite book | title = Painter's Guide to Color: Includes the New Quiller Color Wheel | author = Stephen Quiller | publisher = Watson-Guptill | year = 1999 | isbn = 0-8230-3913-7 | url = https://books.google.com/books?id=unHoFlKMHTAC&q=%22middle+gray%22&pg=PA36 }}</ref> in photography and printing, it is typically defined as 18% reflectance in visible light.<ref>{{cite book | title = Cinematography: Theory and Practice : Imagemaking for Cinematographers, Directors, and Videographers | author = Blain Brown | publisher = Focal Press | year = 2002 | isbn = 0-240-80500-3 | url = https://books.google.com/books?id=1JL2jFbNPNAC&q=%22middle+gray%22+18%25&pg=PA121 }}</ref><ref>Woods, Mark. ''[https://www.cameraguild.com/member-resources/techtips/how-to-effectively-use-the-gray-card.aspx How to Effectively Use the Gray Card] {{webarchive|url=https://web.archive.org/web/20141129190140/https://www.cameraguild.com/member-resources/techtips/how-to-effectively-use-the-gray-card.aspx |date=2014-11-29 }}''. cameraguild.com</ref>
-Light meters, cameras, and pictures are often calibrated using an 18% [[gray card]]<ref>{{cite book | title = The Motion Picture Image: From Film to Digital | author = Steven Barclay | publisher = Focal Press | year = 1999 | isbn = 0-240-80390-6 | url = https://books.google.com/books?id=9qRzglF7GsYC&q=%22middle+gray%22+18%25+gray-card+calibrating&pg=PA38 }}</ref><ref name=Spottiswoode>''Film and Its Techniques'' by Raymond Spottiswoode</ref><ref>''Gevaert Manual of Photography'', ed. A.H.S. Craeybeckx</ref> or a [[color chart|color reference card]] such as a [[ColorChecker]].<ref>C. S. McCamy, H. Marcus, and J. G. Davidson (1976). [https://home.cis.rit.edu/~cnspci/references/mccamy1976.pdf "A Color-Rendition Chart"]. ''Journal of Applied Photographic Engineering'' '''2'''(3). 95–99.</ref><ref>''Shoptalk: a new tool for checking color photography'' by Norman Goldberg</ref><ref>''How to Photograph Landscapes & Scenic Views'' by David Brooks</ref> On the assumption that 18% is similar to the average reflectance of a scene, a grey card can be used to estimate the required exposure of the film.<ref name=Spottiswoode/>
+Light meters, cameras, and pictures are often calibrated using an 18% [[gray card]]<ref>{{cite book | title = The Motion Picture Image: From Film to Digital | author = Steven Barclay | publisher = Focal Press | year = 1999 | isbn = 0-240-80390-6 | url = https://books.google.com/books?id=9qRzglF7GsYC&q=%22middle+gray%22+18%25+gray-card+calibrating&pg=PA38 }}</ref><ref name=Spottiswoode>''Film and Its Techniques'' by Raymond Spottiswoode</ref><ref>''Gevaert Manual of Photography'', ed. A.H.S. Craeybeckx</ref> or a [[color chart|color reference card]] such as a [[ColorChecker]].<ref>C. S. McCamy, H. Marcus, and J. G. Davidson (1976). [https://home.cis.rit.edu/~cnspci/references/mccamy1976.pdf "A Color-Rendition Chart"]. ''Journal of Applied Photographic Engineering'' '''2'''(3). 95–99.</ref><ref>''Shoptalk: a new tool for checking color photography'' by Norman Goldberg</ref><ref>''How to Photograph Landscapes & Scenic Views'' by David Brooks</ref> On the assumption that 18% is similar to the average reflectance of a scene, a gray card can be used to estimate the required exposure of the film.<ref name=Spottiswoode/>
 ==History==
 Following the [[Weber–Fechner law]], at the start of the 20th century human lightness perception was assumed to be logarithmic. In 1903, ''The New International Encyclopædia'' illustrated this concept by stating that given a black and white with a luminance ratio of 1:60 (<span style=background:#232323>　</span>&nbsp;:&nbsp;<span style="background:white;border:1px solid#232323">　</span>), the [[geometric mean]] had to be used to find the middle gray.<ref>{{cite book | title = The New International Encyclopædia |author1=Daniel Coit Gilman |author2=Harry Thurston Peck |author3=Frank Moore Colby  |name-list-style=amp | publisher = Dodd, Mead and Company | year = 1903 | url =https://archive.org/details/newinternationa06gilm/page/128}}</ref> That is equivalent to a relative luminance of 12.9% (<span style=background:#656565>　</span>).
-When Munsell was developing [[Munsell color system|his colour system]], he tried to ascertain the relation between luminance and perceived lightness. As early as 1906, he wrote: 'Should we use logarithmic curve or curve of squares?'<ref>{{cite journal|title=The early development of the Munsell system|first=Rolf G.|last=Kuehni|volume=27|issue=1|pages=20–27|doi=10.1002/col.10002|date=February 2002|journal=Color Research & Application}}</ref> In 1920 Priest, Gibson, and McNicholas showed using both a König-Martens spectrophotometer and an apparatus designed by Gibson where the outputs of two photocells are balanced<ref>First the photocells are illuminated by lamps and their outputs are balanced without the sample present; then the sample is placed at one cell and the lamp illuminating the other cell is moved further away until the outputs rebalance. For a more detailed description see K.S. Gibson, ''Photoelectric spectrophotometry using the null method''.</ref> that the shades in Munsell's 1915 atlas followed a square root curve, which was later confirmed by extensive experiments.<ref>{{Cite journal|first1=Irwin G.|last1=Priest|last2=Gibson|first2=K.S.|last3=McNicholas|first3=H.J.|title=An examination of the Munsell color system. I: Spectral and total reflection and the Munsell scale of Value|journal=Technical Paper 167|page=27|issue=3|publisher=United States Bureau of Standards|date=September 1920}}</ref><ref>Munsell AEO, Sloan LL, Godlove IH. Neutral value scales I, Munsell neutral value scale. J Opt Soc Am 1933;23:394 – 401</ref> In Munsell's system, the shades of neutral gray were labelled N<sup style=text-decoration:underline>1</sup> to N<sup style=text-decoration:underline>9</sup>, with N<sup style=text-decoration:underline>5</sup> in the middle and 0 and 10 denoting the unachievable ideal black and perfect white.<ref>{{Cite journal|first1=Irwin G.|last1=Priest|last2=Gibson|first2=K.S.|last3=McNicholas|first3=H.J.|title=An examination of the Munsell color system. I: Spectral and total reflection and the Munsell scale of Value|journal=Technical Paper 167|page=27|issue=3|publisher=United States Bureau of Standards|date=September 1920}}</ref>
+When [[Albert Henry Munsell]] was developing [[Munsell color system|his color system]], he tried to ascertain the relation between luminance and perceived lightness. As early as 1906, he wrote: 'Should we use logarithmic curve or curve of squares?'<ref>{{cite journal|title=The early development of the Munsell system|first=Rolf G.|last=Kuehni|volume=27|issue=1|pages=20–27|doi=10.1002/col.10002|date=February 2002|journal=Color Research & Application}}</ref> In 1920 Priest, Gibson, and McNicholas showed using both a König-Martens spectrophotometer and an apparatus designed by Gibson where the outputs of two photocells are balanced<ref>First the photocells are illuminated by lamps and their outputs are balanced without the sample present; then the sample is placed at one cell and the lamp illuminating the other cell is moved further away until the outputs rebalance. For a more detailed description see K.S. Gibson, ''Photoelectric spectrophotometry using the null method''.</ref> that the shades in Munsell's 1915 atlas followed a square root curve, which was later confirmed by extensive experiments.<ref>{{Cite journal|first1=Irwin G.|last1=Priest|last2=Gibson|first2=K.S.|last3=McNicholas|first3=H.J.|title=An examination of the Munsell color system. I: Spectral and total reflection and the Munsell scale of Value|journal=Technical Paper 167|page=27|issue=3|publisher=United States Bureau of Standards|date=September 1920}}</ref><ref>Munsell AEO, Sloan LL, Godlove IH. Neutral value scales I, Munsell neutral value scale. J Opt Soc Am 1933;23:394 – 401</ref> In Munsell's system, the shades of neutral gray were labelled N<sup style=text-decoration:underline>1</sup> to N<sup style=text-decoration:underline>9</sup>, with N<sup style=text-decoration:underline>5</sup> in the middle and 0 and 10 denoting the unachievable ideal black and perfect white.<ref>{{Cite journal|first1=Irwin G.|last1=Priest|last2=Gibson|first2=K.S.|last3=McNicholas|first3=H.J.|title=An examination of the Munsell color system. I: Spectral and total reflection and the Munsell scale of Value|journal=Technical Paper 167|page=27|issue=3|publisher=United States Bureau of Standards|date=September 1920}}</ref>
-In 1933, Alexander Ector Orr Munsell ([[Albert Henry Munsell]]'s son) found "that a series of neutral reflecting surfaces whose reflectances are ..., 18.0, ..., and 100.0 percent, ..., form for the average observer a series of equal differences in value."<ref>Munsell AEO, Sloan LL, Godlove IH. Neutral value scales I, Munsell neutral value scale. J Opt Soc Am 1933;23:394 – 401</ref>
+In 1933, Alexander Ector Orr Munsell (Albert Henry Munsell's son) found "that a series of neutral reflecting surfaces whose reflectances are...18.0...and 100.0 percent...form for the average observer a series of equal differences in value."<ref>Munsell AEO, Sloan LL, Godlove IH. Neutral value scales I, Munsell neutral value scale. J Opt Soc Am 1933;23:394 – 401</ref>
-From the 1930s onward various lightness curves were proposed, but halfway through the 20th century, the proposals settled on cube-root-based curves. In 1976 the [[International Commission on Illumination]] defined the [[CIELAB color space]],<ref>CIE Colorimetry–Part 4: 1976 L* a* b* Colour Space</ref> an extension of which<ref>H. Pauli, ''Proposed extension of the CIE recommendation on "Uniform color spaces, color difference equations, and metric color terms"''</ref> would become the standard for the coming decades in a variety of applications.<ref>Kenichiro Masaoka, Fu Jiang, Mark D. Fairchild & Rodney L. Heckaman, ''Analysis of color volume of multi-chromatic displays using gamut rings''</ref> Following research in the 80s, in the 90s more and more advanced models of colour vision were developed, the first major step being [[CIECAM97s]]; see [[Lightness#1933|Lightness § 1933]] for details.
+From the 1930s onward various lightness curves were proposed, but halfway through the 20th century, the proposals settled on cube-root-based curves. In 1976 the [[International Commission on Illumination]] defined the [[CIELAB color space]],<ref>CIE Colorimetry–Part 4: 1976 L* a* b* Colour Space</ref> an extension of which would become the standard for the coming decades in a variety of applications.<ref>H. Pauli, ''Proposed extension of the CIE recommendation on "Uniform color spaces, color difference equations, and metric color terms"''</ref><ref>Kenichiro Masaoka, Fu Jiang, Mark D. Fairchild & Rodney L. Heckaman, ''Analysis of color volume of multi-chromatic displays using gamut rings''</ref> Following research in the 80s and 90s, more and more advanced models of color vision were developed, the first major step being [[CIECAM97s]]; see [[Lightness#1933|Lightness § 1933]] for details.
 ==Table of middle grays==
 Below are various "middle" grays based on various criteria.
-<onlyinclude>The shades in the rightmost column will only be correct if viewed on a calibrated monitor; you can check if the 50% luminance level of your monitor is correct [https://jsfiddle.net/L47ysmtw here]. If the hatched rectangle does not appear to be of the same brightness, then the "middle grays" rendered in the table are not correctly displayed on your screen.
+<onlyinclude>The shades in the rightmost column will only be correct if viewed on a calibrated monitor.
-Note that LCD screens, even when correctly calibrated, often have a brightness that varies considerably depending on the viewing angle. When using the luminance level checker above, try stepping back and changing your position until the hatched rectangle in the center of the gray field appears to dissolve into the background.
+Note that LCD screens, even when correctly calibrated, often have a brightness that varies considerably depending on the viewing angle.
 {| class="wikitable sortable" style="text-align:center"
@@ Line 32: / Line 29: @@
 |style="font-weight:bold;text-align:left"|Munsell, Sloan & Godlove||1933||18%||style="background:#767676;height:3.2em"data-sort-value=118|
 |-
-|style="font-weight:bold;text-align:left"|[[CIELAB|L*a*b*]]||1976||18.42%||style="background:#777777;height:3.2em"data-sort-value=119|
+|style="font-weight:bold;text-align:left"|[[CIELAB]]||1976||18.42%||style="background:#777777;height:3.2em"data-sort-value=119|
 |-
 |style="font-weight:bold;text-align:left"|[[sRGB]]||1996||21.40%||style="background:#808080;height:3.2em"data-sort-value=128|