Editing Additive color

{{short description|Model for predicting color created by mixing visible light}}
{{use mdy dates|date=September 2021}}
{{Use American English|date=October 2020}}
[[File:RGB combination on wall.png|thumb|Red, green, and blue lights combining by reflecting from a white wall: secondary colors yellow, cyan, and magenta are found at the intersections of red and green, green and blue, and blue and red. The intersection of all three primary colors together yields white.]]
[[File:J C Maxwell with top.jpg|thumb|[[James Clerk Maxwell]], with his color top that he used for investigation of color vision and additive color]]

'''Additive color''' or '''additive mixing''' is a property of a [[color model]] that predicts the appearance of [[color]]s made by coincident component [[light]]s, i.e. the perceived color can be predicted by summing the numeric representations of the component colors.<ref>{{cite web |last1=MacEvoy |first1=Bruce |title=handprint : colormaking attributes |url=https://www.handprint.com/HP/WCL/color5.html#theoryadd |website=www.handprint.com |access-date=26 February 2019}}</ref> Modern formulations of [[Grassmann's laws (color science)|Grassmann's laws]]<ref>{{cite web |last1=MacEvoy |first1=Bruce |title=handprint : colormaking attributes |url=https://www.handprint.com/HP/WCL/color6.html#grassmann |website=www.handprint.com |access-date=26 February 2019}}</ref> describe the additivity in the color perception of light mixtures in terms of algebraic equations. Additive color predicts perception and not any sort of change in the photons of light themselves. These predictions are only applicable in the limited scope of color matching experiments where viewers match small patches of uniform color isolated against a gray or black background.

Additive color models are applied in the design and testing of electronic displays that are used to render realistic images containing diverse sets of color using [[phosphor]]s that emit light of a limited set of [[primary color]]s. Examination with a sufficiently powerful magnifying lens will reveal that each pixel in [[Cathode-ray tube|CRT]], [[Liquid crystal display|LCD]], and most other types of color video displays is composed of red, green, and blue light-emitting phosphors which appear as a variety of single colors when viewed from a normal distance.

Additive color, alone, does not predict the appearance of mixtures of printed color inks, dye layers in color [[photograph]]s on [[photographic film|film]], or paint mixtures. Instead, [[subtractive color]] is used to model the appearance of [[pigment]]s or [[dye]]s, such as those in [[paint]]s and [[ink]]s.

The combination of two of the common three additive [[primary color]]s in equal proportions produces an additive [[secondary color]]—[[cyan]], [[magenta]] or [[yellow]]. Additive color is also used to predict colors from overlapping projected colored lights often used in theatrical lighting for plays, concerts, circus shows, and night clubs.<ref name="briggs">{{cite web|url=http://www.huevaluechroma.com/044.php|title=The Dimensions of Color|author=David Briggs|year=2007|access-date=2011-11-23|url-status=live|archive-url=https://web.archive.org/web/20150928031404/http://www.huevaluechroma.com/044.php|archive-date=2015-09-28}}</ref>

The full [[gamut]] of color available in any additive color system is defined by all the possible combinations of all the possible [[luminosity|luminosities]] of each primary color in that system. In [[chromaticity]] space, a gamut is a plane [[convex polygon]] with corners at the primaries. For three primaries, it is a [[triangle]].

==History ==
[[File:Tartan Ribbon.jpg|thumb|The first permanent color photograph, taken by Thomas Sutton, under the direction of James Clerk Maxwell in 1861]]
Systems of additive color are motivated by the [[Young–Helmholtz theory]] of [[trichromatic color vision]], which was articulated around 1850 by [[Hermann von Helmholtz]], based on earlier work by [[Thomas Young (scientist)|Thomas Young]]. For his experimental work on the subject, [[James Clerk Maxwell]] is sometimes credited as being the father of additive color.<ref>{{cite web | title = James Clerk Maxwell | url = http://www.cis.rit.edu/node/280 | work = Inventor's Hall of Fame, Rochester Institute of Technology Center for Imaging Science | url-status = live | archive-url = https://web.archive.org/web/20100918095755/http://www.cis.rit.edu/node/280 | archive-date = 2010-09-18 }}</ref> He had the photographer [[Thomas Sutton (photographer)|Thomas Sutton]] photograph a tartan ribbon on black-and-white film three times, first with a red, then green, then blue color filter over the lens. The three black-and-white images were developed and then projected onto a screen with three different projectors, each equipped with the corresponding red, green, or blue color filter used to take its image. When brought into alignment, the three images (a black-and-red image, a black-and-green image and a black-and-blue image) formed a full-color image, thus demonstrating the principles of additive color.<ref>{{cite book | title = Exploring Colour Photography: A Complete Guide | author = Robert Hirsch | publisher = Laurence King Publishing | year = 2004 | isbn = 1-85669-420-8 | url = https://books.google.com/books?id=4Gx2WItWGYoC&q=maxwell+additive+color+photograph+register&pg=PA28 | url-status = live | archive-url = https://web.archive.org/web/20170225083437/https://books.google.com/books?id=4Gx2WItWGYoC&pg=PA28&dq=maxwell+additive+color+photograph+register#PPA28,M1 | archive-date = 2017-02-25 }}</ref>

==See also==
[[File:Additive colors.ogv|thumb|Additive color mixing with CD covers]]

* [[Color mixing]]
* [[Color space]]
* [[Color theory]]
* [[Color motion picture film]]
* [[Kinemacolor]]
* [[Prizma|Prizma Color]]
* [[RGB color model]]
* [[Subtractive color]]
* [[Technicolor]]
* [[William Friese-Greene]]

==References==

{{Reflist}}

==External links==
*[http://www.poeticmind.co.uk/research/rgb-cmyk-colour-systems/ RGB and CMYK Colour systems.] 
*[http://www.edinphoto.org.uk/1_P/1_photographers_maxwell.htm http://www.edinphoto.org.uk/1_P/1_photographers_maxwell.htm] - Photos and stories from the James Clerk Maxwell Foundation.
* Stanford University CS 178 [http://graphics.stanford.edu/courses/cs178/applets/colormixing.html interactive Flash demo] comparing additive and subtractive color mixing.

{{Color topics}}

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