MunsellToxyY | R Documentation |
MunsellToxyY
Converts Munsell HVC to xyY coordinates, by interpolating over the
extrapolated Munsell renotation data
MunsellToxyY( MunsellSpec, xyC='NBS', hcinterp='bicubic', vinterp='cubic', YfromV='ASTM', warn=TRUE )
MunsellSpec |
a numeric Nx3 matrix or a vector that can be converted to
such a matrix.
Each row has Munsell HVC, where H is Hue Number,
and V and C are the standard Munsell Value and Chroma.
The Hue is automatically wrapped to the interval (0,100].
| ||||||||||||||||
xyC |
a numeric 2-vector with xy chromaticity of Illuminant C. It can also be one of the strings in the first column of this table; it is then replaced by the corresponding xy in the second column.
The default | ||||||||||||||||
hcinterp |
either | ||||||||||||||||
vinterp |
either | ||||||||||||||||
YfromV |
passed as the parameter | ||||||||||||||||
warn |
if a chip cannot be mapped (usually because the Chroma is too large),
its x and y are set to |
In case hcinterp='bicubic'
or vinterp='cubic'
a Catmull-Rom spline is used;
see the article Cubic Hermite spline.
This spline has the nice property that it is local and requires at most 4 points.
And if the knot spacing is uniform:
1) the resulting spline is C^1,
2) if the knots are on a line, the interpolated points are on the line too.
a data.frame
with these columns:
SAMPLE_NAME |
the original |
HVC |
the input Nx3 matrix, or the HVC matrix converted from the input Munsell notation |
xyY |
the computed output matrix, with CIE xyY coordinates of MunsellSpec illuminated by Illuminant C.
In case of error, x and y are set to |
Even when vinterp='cubic'
the function HVC \rarrow xyY is not C^1
on the plane V=1.
This is because of a change in Value spacing:
when V≥1 the Value spacing is 1, but when V≤1 the Value spacing is 0.2.
When making plots in planes of constant Value,
option hcinterp='bicubic'
makes fairly smooth ovals,
and hcinterp='bilinear'
makes polygons.
The ovals are smooth even when vinterp='linear'
,
but the function is not class C^1 at the planes of integer Value.
To get a fully C^1 function (except at the neutrals and on the plane V=1),
hcinterp
and vinterp
must be set to the defaults.
Jose Gama and Glenn Davis
Paul Centore 2014
The Munsell and Kubelka-Munk Toolbox
https://www.munsellcolourscienceforpainters.com/MunsellAndKubelkaMunkToolbox/MunsellAndKubelkaMunkToolbox.html
https://www.rit.edu/science/munsell-color-lab
https://www.rit-mcsl.org/MunsellRenotation/all.dat
https://www.rit-mcsl.org/MunsellRenotation/real.dat
Judd, Deane B. The 1931 I.C.I. Standard Observer and Coordinate System for Colorimetry. Journal of the Optical Society of America. Vol. 23. pp. 359-374. October 1933.
Newhall, Sidney M., Dorothy Nickerson, Deane B. Judd. Final Report of the O.S.A. Subcommitte on the Spacing of the Munsell Colors. Journal of the Optical Society of America. Vol. 33. No. 7. pp. 385-418. July 1943.
Kelly, Kenneth L. Kasson S. Gibson. Dorothy Nickerson. Tristimulus Specification of the Munsell Book of Color from Spectrophometric Measurements National Bureau of Standards RP1549 Volume 31. August 1943.
Judd, Deane B. and Günther Wyszecki. Extension of the Munsell Renotation System to Very Dark Colors. Journal of the Optical Society of America. Vol. 46. No. 4. pp. 281-284. April 1956.
National Television System Committee. [Report and Reports of Panel No. 11, 11-A, 12-19, with Some supplementary references cited in the Reports, and the Petition for adoption of transmission standards for color television before the Federal Communications Commission] (1953)
Rheinboldt, Werner C. and John P. Menard. Mechanized Conversion of Colorimetric Data to Munsell Renotations. Journal of the Optical Society of America. Vol. 50, Issue 8, pp. 802-807. August 1960.
Wikipedia. Cubic Hermite spline. https://en.wikipedia.org/wiki/Cubic_Hermite_spline
Paul Centore 2014 The Munsell and Kubelka-Munk Toolbox https://www.munsellcolourscienceforpainters.com/MunsellAndKubelkaMunkToolbox/MunsellAndKubelkaMunkToolbox.html
xyYtoMunsell()
MunsellToxyY( '7.6P 8.9/2.2' ) ## SAMPLE_NAME HVC.H HVC.V HVC.C xyY.x xyY.y xyY.Y ## 1 7.6P 8.9/2.2 87.6 8.9 2.2 0.3109520 0.3068719 74.6134498
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