Editing Primary color (section)

=== Real primaries ===
[[File:CIE1931xy_gamut_comparison.svg |thumb|300px|various RGB color spaces are represented as [[color triangle]]s with vertices that represent the primaries. The [[CIE 1931 color space|1931 CIE chromaticity diagram]] shows the gamut of the standard observer. Primaries outside of the colored region are imaginary.]]

Color spaces used in [[color reproduction]] must use real primaries that can be reproduced by practical sources, either lights in additive models, or pigments in subtractive models. Most [[RGB color spaces]] have real primaries, though some maintain imaginary primaries. For example, all the [[sRGB]] primaries fall within the gamut of human perception, and so can be easily represented by practical light sources, including CRT and LED displays, hence why sRGB is still the color space of choice for digital displays.

A color in a color space is defined as a combination of its primaries, where each primary must give a non-negative contribution. Any color space based on a finite number of real primaries is ''incomplete'' in that it cannot reproduce every color within the gamut of the standard observer.

Practical color spaces such as [[sRGB]]<ref name="sRGB_orig">{{cite web|author1=Michael Stokes|author2=Matthew Anderson|author3=Srinivasan Chandrasekar|author4=Ricardo Motta|date=5 November 1996|title=A Standard Default Color Space for the Internet – sRGB, Version 1.10|url=https://www.w3.org/Graphics/Color/sRGB.html <!-- ALTERNATIVE URL: http://www.color.org/sRGB.xalter -->|archive-url=|archive-date=|access-date=|website=}}</ref> and [[scRGB]]<ref name="iec-standard">{{Cite web|url=https://webstore.iec.ch/publication/6171|title=Multimedia systems and equipment - Colour measurement and management - Part 2-2: Colour management - Extended RGB colour space - scRGB|date=23 January 2003|access-date=18 April 2021|author1=HP|author-link1=Hewlett-Packard|author2=Microsoft|author-link2=Microsoft|author3=IEC|author-link3=International Electrotechnical Commission|editor=IEC|website=IEC}}</ref> are typically (at least partially) defined in terms of linear transformations from CIE XYZ, and [[color management]] often uses CIE XYZ as a middle point for transformations between two other color spaces.

Most color spaces in the color-matching context (those defined by their relationship to CIE XYZ) inherit its three-dimensionality. However, more complex [[color appearance model]]s like [[CIECAM02]] require extra dimensions to describe colors appear under different viewing conditions.<ref>{{cite book |last1=Fairchild |first1=Mark D. |title=Color Appearance Models. |date=2013 |publisher=Wiley |location=Hoboken |isbn=9781119967033 |page=287 |edition=3rd}}</ref>

{{clear}}