World Library  
Flag as Inappropriate
Email this Article

CIE 1960 color space

Article Id: WHEBN0015307810
Reproduction Date:

Title: CIE 1960 color space  
Author: World Heritage Encyclopedia
Language: English
Subject: Color space, CIE 1964 color space, Mired, Color temperature, Ostwald color system
Collection: Color Space
Publisher: World Heritage Encyclopedia
Publication
Date:
 

CIE 1960 color space

The Planckian locus on the MacAdam (u, v) chromaticity diagram. The normals are lines of equal correlated color temperature.

The CIE 1960 color space ("CIE 1960 UCS", variously expanded Uniform Color Space, Uniform Color Scale, Uniform Chromaticity Scale, Uniform Chromaticity Space) is another name for the (u, v) chromaticity space devised by David MacAdam.[1]

The CIE 1960 UCS does not define a luminance or lightness component, but the Y tristimulus value of the XYZ color space or a lightness index similar to W* of the CIE 1964 color space are sometimes used.[2]

Today, the CIE 1960 UCS is mostly used to calculate correlated color temperature, where the isothermal lines are perpendicular to the Planckian locus. As a uniform chromaticity space, it has been superseded by the CIE 1976 UCS.

Contents

  • Background 1
  • Relation to CIE XYZ 2
  • Relation to CIELUV 3
  • References 4
  • External links 5

Background

Judd determined that a more uniform color space could be found by a simple projective transformation of the CIEXYZ tristimulus values:[3]

\begin{pmatrix} ''R'' \\ ''G'' \\ ''B'' \end{pmatrix} = \begin{pmatrix} 3.1956 & 2.4478 & -0.1434 \\ -2.5455 & 7.0492 & 0.9963 \\ 0.0000 & 0.0000 & 1.0000 \end{pmatrix} \begin{pmatrix} X \\ Y \\ Z \end{pmatrix}

(Note: What we have called "G" and "B" here are not the G and B of the CIE 1931 color space and in fact are "colors" that do not exist at all.)

Judd was the first to employ this type of transformation, and many others were to follow. Converting this RGB space to chromaticities one finds[4]

Judd's UCS, with the Planckian locus and the isotherms from 1,000K to 10,000K, perpendicular to the locus. Judd then translated these isotherms back into the CIEXYZ color space. (The colors used in this illustration are illustrative only and do not correspond to the true colors represented by the respective points.)

u=\frac{0.4661x+0.1593y}{y-0.15735x+0.2424}

v=\frac{0.6581y}{y-0.15735x+0.2424}

or equivalently (for comparative purposes with the equations to follow):

u=\frac{5.5932x+1.9116y}{12y-1.882x+2.9088}

v=\frac{7.8972y}{12y-1.882x+2.9088}

MacAdam simplified Judd's UCS for computational purposes:

u = \frac{4x}{12y - 2x + 3}

v = \frac{6y}{12y - 2x + 3}

The Colorimetry committee of the CIE considered MacAdam's proposal at its 14th Session in Brussels for use in situations where more perceptual uniformity was desired than the (x,y) chromaticity space,[5] and officially adopted it as the standard UCS the next year.[6]

Relation to CIE XYZ

The CIE 1960 UCS, also known as the MacAdam (u,v) chromaticity diagram. Colors outside the colored triangle cannot be represented on most computer screens.

U, V, and W can be found from X, Y, and Z using:

U= \textstyle{\frac{2}{3}}X
V=Y\,
W=\textstyle{\frac{1}{2}}(-X+3Y+Z)

Going the other way:

X=\textstyle{\frac 32}U
Y=V
Z=\textstyle{\frac{3}{2}}U-3V+2W

We then find the chromaticity variables as:

u =\frac U{U+V+W}= \frac{4X}{X + 15Y +3Z}
v =\frac V{U+V+W}= \frac{6Y}{X + 15Y + 3Z}

We can also convert from u and v to x and y:

x = \frac{3u}{2u - 8v + 4}
y = \frac{2v}{2u - 8v + 4}

Relation to CIELUV

u^\prime = u\,
v^\prime = \textstyle{\frac{3}{2}}v\,

References

  1. ^
  2. ^
  3. ^
  4. ^ (recommended reading)
  5. ^
  6. ^

External links

  • Free Windows utility to generate chromaticity diagrams. Delphi source included.
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.