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[[File:Cones SMJ2 E.svg|right|frame|Normalized responsivity spectra of human cone cells, S, M, and L types]] | |||
'''LMS''' is a [[color space]] represented by the response of the three types of [[Cone cell|cones]] of the [[human eye]], named after their [[responsivity]] (sensitivity) at long, medium and short wavelengths. | |||
It is common to use the LMS color space when performing [[chromatic adaptation]] (estimating the appearance of a sample under a different illuminant). | |||
==XYZ to LMS== | |||
Typically, the color to be adapted will be specified in a color space other than LMS, but easily convertible to XYZ. The chromatic adaptation matrix in the [[von Kries transform]] method, however, is diagonal in LMS space, thus the usefulness of a [[transformation matrix]] '''M''' between spaces. The transformation matrices for some chromatic adaptation models in terms of [[CIE 1931 color space|CIEXYZ]] coordinates are presented here. | |||
; Notes : | |||
* All [[tristimulus value]]s are normally calculated using the [[CIE 1931 color space#The CIE standard observer|CIE 1931 2° standard colorimetric observer]].<ref name=fairchild>{{cite book|first=Mark D.|last=Fairchild|title=Color Appearance Models|publisher=[[Wiley Interscience]]|isbn=978-0-470-01216-1|year=2005|edition=2E|url=http://books.google.com/books?id=8_TxzK2B-5MC&pg=PA228&lpg=PA228&dq=hunt+model+tristimulus+matrix&source=web&ots=IRmPqu6kY2&sig=I781mz7ur2tnRKcAC8aM1GH2uWk}}</ref> | |||
* Unless specified otherwise, '''M''' is normalized (the elements in a row add up to unity) so the tristimulus values for an equal-energy illuminant (X=Y=Z), like [[standard illuminant|CIE Illuminant E]], produce equal LMS values.<ref name=fairchild/> | |||
===CMCCAT97=== | |||
The [[CMCCAT97]] color appearance model uses the Bradford transformation matrix (M<sub>B</sub>):<ref>{{cite book|url=http://books.google.com/books?id=zgeuoz_muCIC&pg=PA89&lpg=PA89&dq=ciecam97s+bradford+0.8951&source=web&ots=oJQ6ylBkOz&sig=91sZ-oHpaUHNivWBVyr6XyPm2B4#PPA89,M1|title=Computational Colour Science Using MATLAB|first=Stephen|last=Westland|coauthors=Ripamonti, Caterina|publisher=[[Wiley Interscience]]|page=89|chapter=6.2.2 CMCCAT97|year=2004|isbn=0-470-84562-7}}</ref> | |||
<math> | |||
\begin{bmatrix} | |||
L\\M\\S | |||
\end{bmatrix} | |||
= | |||
\begin{bmatrix} | |||
0.8951 & 0.2664 & -0.1614 \\ | |||
-0.7502 & 1.7135 & 0.0367 \\ | |||
0.0389 & -0.0685 & 1.0296 | |||
\end{bmatrix} | |||
\begin{bmatrix} | |||
X\\Y\\Z | |||
\end{bmatrix} | |||
</math> | |||
===RLAB=== | |||
The [[RLAB]] color appearance model uses the Hunt-Pointer-Estevez (HPE) transformation matrix (M<sub>H</sub>) for conversion from [[CIE 1931 color space|CIE XYZ]] to LMS:<ref name=fairchild/><ref>{{cite conference|title=The CIECAM02 Color Appearance Model|booktitle=IS&T/SID Tenth Color Imaging Conference|last=Moroney|first=Nathan|coauthors=Fairchild, Mark D.; Hunt, Robert W.G.; Li, Changjun; Luo, M. Ronnier; Newman, Todd|url=http://www.polybytes.com/misc/Meet_CIECAM02.pdf|location=[[Scottsdale, Arizona]]|isbn=0-89208-241-0|date=November 12, 2002|publisher=The [[Society for Imaging Science and Technology]]}}</ref> | |||
{| | |||
| Equal-energy illuminants: | |||
| <math> | |||
\begin{bmatrix} | |||
L\\M\\S | |||
\end{bmatrix} | |||
= | |||
\begin{bmatrix} | |||
0.38971 & 0.68898 & -0.07868\\ | |||
-0.22981 & 1.18340 & 0.04641\\ | |||
0.00000 & 0.00000 & 1.00000 | |||
\end{bmatrix} | |||
\begin{bmatrix} | |||
X\\Y\\Z | |||
\end{bmatrix} | |||
</math> | |||
|- | |||
|Normalized to [[CIE Standard Illuminant D65|D65]]: | |||
|<math> | |||
\begin{bmatrix} | |||
L\\M\\S | |||
\end{bmatrix} | |||
= | |||
\begin{bmatrix} | |||
0.4002 & 0.7076 & -0.0808 \\ -0.2263 & 1.1653 & 0.0457 \\ 0 & 0 & 0.9182 | |||
\end{bmatrix} | |||
\begin{bmatrix} | |||
X\\Y\\Z | |||
\end{bmatrix} | |||
</math> | |||
|} | |||
===CAT97s=== | |||
[[CIECAM97s]] uses a spectrally-sharpened Bradford chromatic adaptation matrix:<ref name=fairchild/> | |||
<math> | |||
\begin{bmatrix} | |||
L\\M\\S | |||
\end{bmatrix} | |||
= | |||
\begin{bmatrix} | |||
0.8562 & 0.3372 & -0.1934 \\ | |||
-0.8360 & 1.8327 & 0.0033 \\ | |||
0.0357 & -0.0469 & 1.0112 | |||
\end{bmatrix} | |||
\begin{bmatrix} | |||
X\\Y\\Z | |||
\end{bmatrix} | |||
</math> | |||
===CAT02=== | |||
The chromatic adaptation matrix (M<sub>CAT02</sub>) from the [[CIECAM02]] model is:<ref name=fairchild/> | |||
<math> | |||
\begin{bmatrix} | |||
L\\M\\S | |||
\end{bmatrix} | |||
= | |||
\begin{bmatrix} | |||
0.7328 & 0.4296 & -0.1624\\ | |||
-0.7036 & 1.6975 & 0.0061\\ | |||
0.0030 & 0.0136 & 0.9834 | |||
\end{bmatrix} | |||
\begin{bmatrix} | |||
X\\Y\\Z | |||
\end{bmatrix} | |||
</math> | |||
==See also== | |||
* [[Color balance]] | |||
* [[Color vision]] | |||
* [[Luminosity function]] | |||
* [[Trichromacy]] | |||
==References== | |||
<references/> | |||
{{Color space}} | |||
[[Category:Color space]] | |||
Revision as of 03:28, 14 January 2014
LMS is a color space represented by the response of the three types of cones of the human eye, named after their responsivity (sensitivity) at long, medium and short wavelengths.
It is common to use the LMS color space when performing chromatic adaptation (estimating the appearance of a sample under a different illuminant).
XYZ to LMS
Typically, the color to be adapted will be specified in a color space other than LMS, but easily convertible to XYZ. The chromatic adaptation matrix in the von Kries transform method, however, is diagonal in LMS space, thus the usefulness of a transformation matrix M between spaces. The transformation matrices for some chromatic adaptation models in terms of CIEXYZ coordinates are presented here.
- Notes
- All tristimulus values are normally calculated using the CIE 1931 2° standard colorimetric observer.[1]
- Unless specified otherwise, M is normalized (the elements in a row add up to unity) so the tristimulus values for an equal-energy illuminant (X=Y=Z), like CIE Illuminant E, produce equal LMS values.[1]
CMCCAT97
The CMCCAT97 color appearance model uses the Bradford transformation matrix (MB):[2]
RLAB
The RLAB color appearance model uses the Hunt-Pointer-Estevez (HPE) transformation matrix (MH) for conversion from CIE XYZ to LMS:[1][3]
| Equal-energy illuminants: | |
| Normalized to D65: |
CAT97s
CIECAM97s uses a spectrally-sharpened Bradford chromatic adaptation matrix:[1]
CAT02
The chromatic adaptation matrix (MCAT02) from the CIECAM02 model is:[1]
See also
References
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