Munsell Resources
by Paul Centore
(last updated August 10, 2020)
Measurements of Munsell Books
Spectrophotometric measurements of reflectance spectra
of Munsell books provide useful data
for further analysis. Here are some publicly available sets of measurements. The first four
are measurements of X-Rite's 1976 Munsell Book of Color, made by the University of Joensuu in
1988 or 1989. This article
analyzes the Joensuu measurements, and compares them to more recent measurements.
- Robin Myers
has posted an extensive spectral library online, including many measurements of Munsell
samples. (The program SpectraShop is required for viewing the data.)
- This page
contains the Joensuu measurements of the 1976 matte Munsell book, made with an acousto-optical tunable
filter (AOTF).
- This page
contains the Joensuu measurements of the 1976 matte Munsell book, made with a Perkin-Elmer Lambda 9
spectrophotometer.
- This page
contains the Joensuu measurements of the 1976 glossy Munsell book, made with a Perkin-Elmer Lambda 18
spectrophotometer.
- This page
contains the Joensuu measurements of 32 glossy Munsell chips, made with a Minolta CM-2002 spectrophotometer.
- This textfile contains spectrophotometric
measurements of the reflectance spectra of Munsell samples in X-Rite's 2007 Munsell Book of Color
(Glossy finish). The measurements were made in 2012 with a ColorMunki spectrophotometer.
This file gives the DEs for the
measurements, with respect to the 1943 renotation, and converts them into CIE coordinates for Illuminants
C and D50.
- In 2012, measurements were made of 235 swatches in the 2nd edition of
The New Munsell Student Color Set. Only standard Munsell colours
(those that occur in the 1943 renotation) were measured. A ColorMunki
spectrophotometer was used for the measurements.
This textfile
contains the measured reflectance spectra data.
Conversions between Munsell and CIE Coordinates
The
Munsell and Kubelka-Munk Toolbox contains two Octave/MATLAB routines,
MunsellToxyY.m
and
xyYtoMunsell.m,
that convert between CIE and Munsell coordinates.
Other tools are also available for
converting between Munsell specifications and CIE coordinates:
-
Glenn Davis's gluonics website
has ported some routines from the MAKM toolbox, and provides a very handy interactive Munsell
converter that anybody can use online. Just enter some CIE coordinates (in XYZ or xyY
format), and click to find the Munsell specification, or vice versa. If you only have a
few conversions to make, this site is probably your best destination. (For a colour
description in everyday language, the site also gives
ISCC-NBS system colour designations.)
-
The Colour package for Python
is an open-source project that has also ported some routines from the MAKM toolbox, including
many of the Munsell routines. It's not clear whether conversions between Munsell and
other colour systems have been implemented yet, but the project is currently in progress, so
they'll probably be there soon if they're not there already.
-
The
Virtual Atlas,
produced by the British company VCS Consulting, is
available for free download. The option View: Colour Conversion produces an interface for converting
between Munsell and CIE coordinates. (Set the tabs above the entry area to read "C," "1931," "Munsell
Aim," and "CIE Yxy." Then enter a Munsell string into the entry area and press "Go!" to convert
that Munsell string to CIE coordinates.) The algorithm behind this code is discussed in a
1990 paper (N. S. Smith, T. W. A. Whitfield, & T. J. Wiltshire, "A Colour Notation Conversion
Program," COLOR Research and Application, Vol. 15, Number 6, December
1990, pp. 338-343). The original implementation was in Pascal; the current implementation is
object-oriented.
-
Here
are some open-source C/C++ conversions routines.
-
Here is a Munsell package for R, the open source
statistics program.
-
Jose Gama has started a port of the
Munsell and Kubelka-Munk Toolbox to R.
-
Psychtoolbox-3 is a set of open source routines that run in Matlab,
so they should work in Octave as well. This toolbox is developed mainly at the University of
Pennsylvania, where it is used for vision research. Currently, it has code to convert from Munsell to xyY,
but not from xyY to Munsell.
-
Wallkill color produces commercial software that
can be used interactively to make Munsell conversions. For $9.95 (as of Jan. 8, 2012), one can buy
a one-year license for the basic Wallkill program. In the basic
program, Munsell specifications can be entered manually, one
at a time, and converted to xyY coordinates, and vice versa. One glitch is that the program
will terminate, and must be restarted, if the entered specification is outside the MacAdam limits. The
Wallkill program runs only on older Windows systems.
-
BabelColor's Patch Tool is also commercial software
that performs Munsell conversions.
-
The X-Rite VS450 spectrophotometer measures a colour's reflectance spectrum, and will automatically convert
it to Munsell coordinates. The Konica-Minolta CM-500 does the same. Other spectrophotometers
might provide similar functionality. The Variable Spectro 1 is a very portable and affordable
spectrophotometer that doesn't give an interpolated Munsell specification, but does give the
standard Munsell colour (as listed in the 1943 Renotation) that is nearest to the
measured colour: it returns Munsell value as an integer, chroma as an even integer, and hue as a multiple
of 2.5.
-
A 1987 paper (Frederick T. Simon & Judith A. Frost. "A New Method for the Conversion of
CIE Colorimetric Data to Munsell Notations," COLOR Research and Application,
Vol. 12, Number 5, 1987, pp. 256-260) implemented Munsell conversion code in Fortran, as part
of a thesis project. This code could not be located.
-
A 1980 paper (Michael R. Pointer. "The Gamut of Real Surface
Colours," Color Research and Application, Vol. 5, Number 3, 1980, pp. 145-155)
says, on p. 146, "These Munsell notation data were converted into CIE coordinates
using an extrapolation program." The program is attributed to a personal communication
from L.E. DeMarsh in 1977. This program could not be located.
Conversions between Munsell and RGB Systems
-
Here is a helpful online discussion about the problem of converting Munsell
specifications to RGB coordinates.
-
The discussion above suggested this
free software for Munsell conversions. It is helpful for visualization, but only runs on PCs.
-
The article
Conversions Between the Munsell and sRGB Colour Systems
provides a technical discussion of the issue, and resulted in two files (one for going from
Munsell to sRGB, and one for the opposite direction) in the
The Munsell and Kubelka-Munk Toolbox:
MunsellRenotationTosRGB.txt and
sRGBToMunsell.txt.
-
Timo Teichert has provided a useful spreadsheet,
Munsell-to-RGB-Tables.xlsm (or
Munsell-to-RGB-Tables.xlsx), that visually
implements the data in the two text files above.
Other Open-Source Octave/MATLAB Colour Science Code
In addition to the
Munsell and Kubelka-Munk Toolbox, other open-source Octave/MATLAB code is available for colour
science applications:
-
Colorlab
is a project started at the University of Valencia. Though it seems to be maintained
sporadically, it a useful source of code, most of it fairly well documented.
-
Psychtoolbox-3 is a set of open source routines
that run in Matlab,
so they should work in Octave as well. This toolbox is developed mainly at the University of
Pennsylvania, where it is used for vision research. There is a forum, for which
registration is required.
-
Stephen Westland, Caterina Ripamonti, and Vien Cheung have produced their
Computational Colour Toolbox, which is available at the MATLAB Central file exchange. Among
other topics, there is code for colour appearance models, colour management, and colour
device characterization.
-
optprop is also
availabe at the MATLAB Central file exchange. This toolbox uses sophisticated methods of
representing and passing colour coordinates, and accessing basic illuminant and
colour-matching data. Many of its graphics are three-dimensional. While
three-dimensional graphics work well in MATLAB, Octave's three-dimensional capabilities
are very limited, so not all the code will transfer to Octave.
If anybody else knows of more resources, either for conversions, measurements of Munsell products, or
open-source colour science code, please let me know at {paul ATSIGN isletech.net}, and they
will be added to the lists. Also, anybody is welcome to combine the open-source code listed above
into a more unified and useful form.