munsellinterpol: xyYtoMunsell – R documentation

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xyYtoMunsell

Convert xyY coordinates into a Munsell specification

Description

xyYtoMunsell Converts xyY coordinates into a Munsell specification, by interpolating over the extrapolated Munsell renotation data

Usage

xyYtoMunsell( xyY, xyC='NBS', hcinterp='bicubic', vinterp='cubic',
                     VfromY='ASTM', warn=TRUE, perf=FALSE )

Arguments

`xyY`	a numeric Nx3 matrix with CIE xyY coordinates in the rows, or a vector that can be converted to such a matrix, by row. These are for viewing in an environment with Illuminant C, with Y=100.
`xyC`	a numeric 2-vector with xy chromaticity of Illuminant C. It can also be one of the strings given in `MunsellToxyY()`.
`hcinterp`	either `'bicubic'` or `'bilinear'` (partial matching enabled). See `MunsellToxyY()` for details.
`vinterp`	either `'cubic'` or `'linear'` (partial matching enabled). See `MunsellToxyY()` for details.
`VfromY`	passed as the parameter `which` to the function `VfromY()`. See `VfromY()` for details. Option `'MGO'` is not allowed because then Y>100 when V=10.
`warn`	if an xyY cannot be mapped (usually because the root finder has wandered afar), its H and V are set to `NA` in the returned `data.frame`. Just before returning, if any rows have `NA`, and this argument is `TRUE`, then a warning is logged.
`perf`	if `perf` is `TRUE`, then extra performance related metrics are appended to the returned `data.frame`, see Value.

Details

See MunsellToxyY() and the User Guide - Appendix C.

Value

a data.frame with N rows and these columns:

`xyY`	The input xyY
`HVC`	the computed HVC. H is automatically wrapped to (0,100]. In case of failure, H and C are `NA`.
`SAMPLE_NAME`	a character vector - the Munsell notation for HVC

If perf is TRUE then there are these additional columns:

`time.elapsed`	elapsed time in seconds. If available, the function `microbenchmark::get_nanotime()` is used.
`iterations`	the number of iterations of `rootSolve::multiroot()`
`evalations`	the number of forward (HVC → xyY) function evaluations
`estim.precis`	the estimated precision from `rootSolve::multiroot()`. This is in the HC plane for the Munsell Value easily computed from Y.

If the rownames of xyY are not NULL and have no duplicates, they are copied to the returned data frame.

Warning

Even when vinterp='cubic' the function xyY → HVC 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.

Author(s)

Jose Gama and Glenn Davis

Source

Paul Centore 2014 The Munsell and Kubelka-Munk Toolbox http://centore.isletech.net/~centore/MunsellAndKubelkaMunkToolbox/MunsellAndKubelkaMunkToolbox.html
http://www.rit.edu/science/pocs/renotation
http://www.rit-mcsl.org/MunsellRenotation/all.dat
http://www.rit-mcsl.org/MunsellRenotation/real.dat

References

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.

Paul Centore 2014 The Munsell and Kubelka-Munk Toolbox http://centore.isletech.net/~centore/MunsellAndKubelkaMunkToolbox/MunsellAndKubelkaMunkToolbox.html

Examples

xyYtoMunsell(c(0.310897, 0.306510, 74.613450))
##       xyY.1     xyY.2     xyY.3     HVC.H     HVC.V     HVC.C    SAMPLE_NAME
## 1  0.310897  0.306510 74.613450 87.541720  8.900000  2.247428 7.5P 8.9/2.2

munsellinterpol

Interpolate Munsell Renotation Data from Hue/Chroma to CIE/RGB

v2.6-1

GPL (>= 3)

Authors

Jose Gama [aut, trl], Paul Centore [aut, cph], Glenn Davis [aut, cre]

Initial release

2020-02-02