Editing Chromaticity (section)

{{Short description|Specification of color hue and saturation}}
{{For|the album by Tony MacAlpine|Chromaticity (album)}}

[[File:PlanckianLocus.png|right|thumb|250px|The [[CIE 1931 color space|CIE 1931]] xy chromaticity space, also showing the chromaticities of black-body light sources of various temperatures, and lines of constant [[Color temperature#Correlated color temperature|correlated color temperature]]]]

[[File:SRGB gamut within CIExyY color space mesh.webm|alt=3D Chromaticity Diagram of the WideGamutRGB color space|thumb|sRGB gamut plotted in CIE xyY color space. '''''x'' and ''y'' are the chromaticity axes''', the ''Y'' axis represents (linear) [[Relative luminance|luminance]].]]

'''Chromaticity''' is an objective specification of the quality of a [[color]] regardless of its [[luminance]]. Chromaticity consists of two [[dimension|independent parameters]], often specified as ''[[hue]]'' (''h'') and ''[[colorfulness]]'' (''s''), where the latter is alternatively called ''saturation'', ''chroma'', ''intensity'',<ref>In modern terminology the word ''intensity'' may refer to lightness, not colorfulness.</ref> or ''[[excitation purity]]''.<ref>{{cite book | title = Progress in Optics | author = Emil Wolf | publisher = North Holland Pub. Co | year = 1961 | url = https://books.google.com/books?id=5n7yXmBusL0C&q=chromaticity+hue+purity}}</ref><ref>{{cite book | title = The Focal Encyclopedia of Photography | author = Leslie D. Stroebel, Richard D. Zakia | publisher = Focal Press | year = 1993 | isbn = 978-0-240-51417-8 | url = https://archive.org/details/focalencyclopedi00lesl| url-access = registration | page = [https://archive.org/details/focalencyclopedi00lesl/page/124 124] | quote = chromaticity hue saturation chroma colorfulness purity. }}</ref> This number of parameters follows from [[trichromacy]] of vision of most humans, which is assumed by most models in [[color science]].