Editing Color (section)

=== Spectral colors<span class="anchor" id="Spectral colours"></span> ===
{{main|Spectral color}}
The familiar colors of the [[rainbow]] in the [[visible spectrum|spectrum]]—named using the [[Latin]] word for ''appearance'' or ''apparition'' by [[Isaac Newton]] in 1671—include all those colors that can be produced by visible [[light]] of a single wavelength only, the [[spectral color|''pure spectral'' or ''monochromatic'' color]]s. The spectrum above shows approximate wavelengths (in [[nanometre|nm]]) for spectral colors in the visible range. Spectral colors have 100% [[colorfulness#Excitation purity|purity]], and are fully [[colorfulness|saturate]]d. A complex mixture of spectral colors can be used to describe any color, which is the definition of a light [[power spectrum]].

The spectral colors form a continuous spectrum, and how it is divided into [[color term|distinct colors linguistically]] is a matter of culture and historical contingency.<ref>[[Brent Berlin|Berlin, B.]] and [[Paul Kay|Kay, P.]], ''[[Basic Color Terms: Their Universality and Evolution]]'', Berkeley: [[University of California Press]], 1969.</ref> Despite the ubiquitous [[ROYGBIV]] mnemonic used to remember the spectral colors in English, the inclusion or exclusion of colors is contentious, with disagreement often focused on [[indigo#Classification as a spectral color|indigo]] and cyan.<ref>{{cite book|last=Waldman|first=Gary|title=Introduction to light: the physics of light, vision, and color|year=2002|publisher=Dover Publications|location=Mineola|isbn=978-0486421186|page=193|url=https://books.google.com/books?id=PbsoAXWbnr4C&pg=PA193}}</ref> Even if the subset of color terms is agreed, their wavelength ranges and borders between them may not be.

The ''intensity'' of a spectral color, relative to the context in which it is viewed, may alter its perception considerably. For example, a low-intensity orange-yellow is [[brown]], and a low-intensity yellow-green is [[olive green]]. Additionally, hue shifts towards yellow or blue happen if the intensity of a spectral light is increased; this is called [[Bezold–Brücke shift]]. In [[color models]] capable of representing spectral colors,<ref>{{cite web |title=Perceiving Color |url=http://courses.washington.edu/psy333/lecture_pdfs/chapter7_Color.pdf#page=72 |website=courses.washington.edu}}</ref> such as [[CIELUV]], a spectral color has the maximal saturation. In [[Helmholtz–Kohlrausch effect#Helmholtz color coordinates|Helmholtz coordinates]], this is described as 100% [[Colorfulness#Excitation purity|purity]].