Editing Web colors (section)

{{short description|Color used in designing web pages}}
{{Use dmy dates|date=October 2014}}
{{Use American English|date=October 2020}}
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'''Web colors''' are [[color]]s used in [[Web design|displaying web pages]] on the [[World Wide Web]];  they can be described by way of three methods:  a color may be specified as an [[RGB color model|RGB]] triplet,  in [[hexadecimal]] format (a ''hex triplet'') or according to its common English name in some cases. A [[color tool]] or other [[graphics software]] is often used to generate color values. In some uses, '''hexadecimal color''' codes are specified with notation using a leading [[number sign]] (#).<ref>{{cite book | last = Niederst Robbins | first = Jennifer | title = Web Design in a Nutshell | publisher = O'Reilly |date=February 2006 |page=830 | isbn = 978-0-596-00987-8 |chapter=Appendix D: Specifying Color }}</ref><ref>York, Richard. ''Beginning CSS'', pp. 71–72.</ref> A color is specified according to the intensity of its red, green and blue components, each represented by eight [[bit]]s. Thus, there are 24 bits used to specify a web color within the [[sRGB]] gamut, and 16,777,216 colors that may be so specified.

Colors outside the sRGB gamut can be specified in [[CSS|Cascading Style Sheets]] by making one or more of the red, green and blue components negative or greater than 100%, so the color space is theoretically an unbounded extrapolation of sRGB similar to [[scRGB]].<ref>{{cite web |url=https://www.w3.org/TR/css3-color/#rgb-color |at=section 4.2.1. RGB color values |title=CSS Color Module Level 3 |date=7 June 2011 |publisher=W3C |editor1-first=Tantek |editor1-last=Çelik |editor2-first=Chris |editor2-last=Lilley |editor3-first=L. David |editor3-last=Baron |first1=Steven |last1=Pemberton |first2=Brad |last2=Pettit }}</ref> Specifying a non-sRGB color this way requires the <code>RGB()</code> function call. It is impossible with the hexadecimal syntax (and thus impossible in legacy [[HTML]] documents that do not use CSS).

The first versions of [[Mosaic (web browser)|Mosaic]] and [[Netscape Navigator]] used the [[X11 color names]] as the basis for their color lists, as both started as [[X Window System]] applications.
Web colors have an unambiguous colorimetric definition, [[sRGB]], which relates the [[chromaticity|chromaticities]] of a particular [[phosphor]] set, a given transfer curve, adaptive whitepoint, and viewing conditions.<ref>{{cite book |last1=Sharma |first1=Gaurav |last2=Bala |first2=Raja |title=Digital Color Imaging Handbook |date=19 December 2017 |publisher=CRC Press |isbn=978-1-4200-4148-4 |url=https://books.google.com/books?id=OxlBqY67rl0C&q=srgb&pg=PA89 |language=en}}</ref> These have been chosen to be similar to many real-world [[Computer monitor|monitors]] and viewing conditions, to allow rendering to be fairly close to the specified values even without [[color management]]. [[User agent]]s vary in the fidelity with which they represent the specified colors. More advanced user agents use color management to provide better color fidelity; this is particularly important for [[Web-to-print]] applications.