Editing Brown (section)

=== Optics ===
Brown is a dark orange color. It can be thought of as dark [[orange (color)|orange]], but it can also be made in other ways. In the [[RGB color model]], which uses red, green and blue light in various combinations to make all the colors on computer and television screens, it is made by mixing red and green light.

In terms of the [[visible spectrum]], "brown" refers to long wavelength hues, [[yellow]], [[orange (colour)|orange]], or [[red]], in combination with low [[luminance]] or [[Saturation (color theory)|saturation]].<ref>"Some Experiments on Color", ''Nature'' '''111''', 1871, in {{cite book | title = Scientific Papers | author = [[John William Strutt]] (Lord Rayleigh) | year = 1899 | publisher = University Press | url = https://books.google.com/books?id=KWMSAAAAIAAJ&q=date:0-1923+light+red+green+yellow-or-orange&pg=PA84 }}</ref>
Since ''brown'' may cover a wide range of the visible spectrum, composite adjectives are used such as red brown, yellowish brown, dark brown or light brown.

As a color of low intensity, brown is a [[tertiary color]]: a mix of the three subtractive [[primary color]]s is brown if the [[cyan]] content is low. Brown exists as a color perception only in the presence of a brighter color contrast.<ref>"Color Vision", in {{cite book | title = The Feynman Lectures on Physics | author = [[Richard Feynman]] | year = 1964 | publisher = Addison Wesley Longman | url = https://feynmanlectures.caltech.edu/I_35.html}}</ref> Yellow, orange, red, or rose objects are still perceived as such if the general illumination level is low, despite reflecting the same amount of red or orange light as a brown object would in normal lighting conditions.
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File:Optical grey squares orange brown.svg|The colored disks appear to be brown and orange, but are actually an identical shade; their perceived color depends on the shade of grey they are surrounded by<ref>G. M. Johnson and M. D. Fairchild, "Visual psychophysics and color appearance", (chapter) in ''CRC Digital Color Imaging Handbook'', 115–171 (2003).</ref>
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