function [xRen yRen YRen] = MakeExtrapolatedRenotationMatrices();
% Purpose Convert the extrapolated Munsell renotation data into three MATLAB matrices.
%
% Description The Munsell system specifies a local colour by giving its hue (H), value (V),
% and chroma(C) in the form HV/C. The value is a number between 0 and 10,
% although for practical purposes value usually ranges only from 1 to 9.
% The chroma is a positive number, whose bound depends on hue and value,
% as given by the MacAdam limits. The hue specification consists of a letter
% designator (B, BG, G, GY, Y, YR, R, RP, P, PB), and a number designator
% which is greater than 0, and less than or equal to 10. If chroma is
% 0, then the local colour has no hue, and is specified as NV, where N is the
% string "N," and V is the value. For example, 5.6R8.2/4.1 is a light pastel
% red, while N3 is a dark grey.
%
% The Commission Internationale de l'Eclairage (CIE) uses a different system
% for specifying colours. In their system, standardized in 1931,
% a coloured light source is specified by three coordinates: x, y, and Y.
% The coordinate Y gives a colour's luminance, or relative luminance.
% When interpreted as a
% relative luminance, as will be done here, Y is a number between 0 and
% 100, that expresses the intensity of the source as a percentage of some
% maximum intensity. This percentage is calculated with regard to the
% human photopic luminous efficiency function, which has been established
% as part of the CIE 2 degree standard observer. When dealing with
% physical samples such as paints, Y is the percentage of a fixed light
% source that a paint sample reflects (with regard to the standard
% observer).
%
% The coordinates x and y are chromaticity coordinates. While Y
% indicates, roughly speaking, how light or dark a colour is, x and y
% indicate hue and chroma. For example, the colour might be saturated red,
% or a dull green. The CIE chromaticity diagram ([Foley1990, Sect. 13.2.2])
% displays all chromaticities that are possible for a light source of a fixed
% luminance, when the light source is viewed in isolation.
%
% There is a conceptual difficulty in converting between Munsell specifications
% and CIE coordinates. The difficulty occurs because the Munsell system
% applies to local colours, which are defined by spectral reflectance
% functions, and CIE coordinates apply to coloured lights, which are defined
% by spectral power distributions (SPD). The 1943 Munsell renotation ([Newhall1943])
% bridged this gap by fixing Illuminant C as a light source,
% that illuminates the local colour. The local colour is specified in the
% Munsell system, and the light reflecting off the local colour is analyzed
% in terms of CIE coordinates. The Y value is the percentage of light,
% originally of an Illuminant C SPD, that the local colour reflects,
% measured in terms of the CIE standard observer. The x and y chromaticity
% coordinates can be found for the reflected light.
%
% The Munsell renotation went further, by using assessments from 40 human
% observers of Munsell hue, value, and chroma. The results of these assessments
% were averaged, to express xyY coordinates as smooth functions of
% Munsell samples. The renotation used samples from the 1929 Munsell Book of
% Color, and recommended some changes, summarized in Table III of
% [Newhall1943]. For example, the 1929 sample 2.5R8/4 was renotated to
% 2.0R7.8/3.1. The 1943 Munsell renotation is a standard today, and supersedes
% previous versions of the Munsell system.
%
% The conversion data for the Munsell renotation was originally given as
% a look-up table, expressing a Munsell specification in xyY coordinates
% ([Newhall1943, Table I]). Grey values were not included in this table;
% according to ([Newhall1943, p. 386]), the xy coordinates of any neutral grey
% are the xy coordinates of the white point of Illuminant C.
% The renotation matrices made by the current routine include all the data
% from ([Newhall1943, Table I]), and augment it with data for greys.
%
% To aid in interpolation, the renotation data has been
% extrapolated, sometimes beyond the MacAdam limits, in the file all.dat from
% [MCSL2010]. The file all.dat has been renamed ExtrapolatedMunsellRenotation.txt,
% and a description has been added to the top of the file. This routine
% uses the extrapolated renotation data.
%
% This routine makes three data matrices (xRen, yRen, and YRen), one for
% each of x, y, and Y. The three matrices
% give the x, y, and Y coordinates for the extrapolated Munsell renotations.
% Each matrix is triply indexed. The three indices,
% which are identical for each matrix, are HueIndex, Value Index, and Chroma Index.
%
% HueIndex goes from 0 to 41, corresponding to Munsell hues, as follows:
% 1 2.5R | 9 2.5Y | 17 2.5G | 25 2.5B | 33 2.5P | 41 N
% 2 5R | 10 5Y | 18 5G | 26 5B | 34 5P |
% 3 7.5R | 11 7.5Y | 19 7.5G | 27 7.5B | 35 7.5P |
% 4 10R | 12 10Y | 20 10G | 28 10B | 36 10P |
% 5 2.5YR | 13 2.5GY | 21 2.5BG | 29 2.5PB | 37 2.5RP |
% 6 5YR | 14 5GY | 22 5BG | 30 5PB | 38 5RP |
% 7 7.5YR | 15 7.5GY | 23 7.5BG | 31 7.5PB | 39 7.5RP |
% 8 10YR | 16 10GY | 24 10BG | 32 10PB | 40 10RP |
% In addition to chromatic colours, neutral greys are given a hue index of 41.
%
% ValueIndex runs from 1 to 9, and is equal to the Munsell value.
%
% ChromaIndex runs from 1 to 19, and is half the Munsell chroma. Greys, whose
% chroma is 0, are assigned a ChromaIndex of 20.
%
% The three matrices contain entries of NaN for Munsell specifications
% that are beyond the extrapolated renotation data. Note that some of the
% extrapolated data is beyond the MacAdam limits.
%
% The three matrices are combined as fields of a structure, named
% ExtrapolatedRenotationMatrices. This routine saves that structure
% in a .mat file, for use by other ColorLab routines.
%
% [Foley1990] James D. Foley, Andries van Dam, Steven K. Feiner, & John
% F. Hughes, Computer Graphics: Principles and Practice, 2nd ed.,
% Addison-Wesley Publishing Company, 1990.
% [MCSL2010] http://www.cis.rit.edu/mcsl/online/munsell.php, as of June 12, 2010
% [Newhall1943] S. M. Newhall, D. Nickerson, & D. B. Judd, "Final
% Report of the O.S.A. Subcommittee on the Spacing of the Munsell
% Colors," Journal of the Optical Society of America, Vol. 33,
% Issue 7, pp. 385-418, 1943.
%
% Syntax [xRen yRen YRen] = MakeExtrapolatedRenotationMatrices();
%
% xRen, yRen, YRen Matrices for Munsell renotation data. See Description
% for details.
%
% Related
% Functions
%
% Required roo2xy
% Functions
%
% Author Paul Centore (September 5, 2010)
% Revision Paul Centore (May 9, 2012)
% ---Changed ! to ~ so that code would work in both Matlab and Octave.
% Revision Paul Centore (December 26, 2012)
% ---Moved from MunsellConversions program to MunsellToolbox.
% Revision Paul Centore (August 31, 2013)
% ---Moved from MunsellToolbox program to MunsellAndKubelkaMunkToolbox.
% Revision Paul Centore (Jan. 1, 2014)
% ---Replaced call to IlluminantCWhitePoint with call to roo2xy (from OptProp).
%
% Copyright 2010, 2012, 2014 Paul Centore
%
% This file is part of MunsellAndKubelkaMunkToolbox.
%
% MunsellAndKubelkaMunkToolbox is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
%
% MunsellAndKubelkaMunkToolbox is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with MunsellAndKubelkaMunkToolbox. If not, see .
% Initialize three extrapolated renotation matrices with NaN everywhere
xRen = NaN * ones(41,9,20);
yRen = NaN * ones(41,9,20);
YRen = NaN * ones(41,9,20);
% Make list of Munsell hues for which renotation data is available
HueList = {'2.5R', '5R', '7.5R', '10R',...
'2.5YR', '5YR', '7.5YR', '10YR',...
'2.5Y', '5Y', '7.5Y', '10Y',...
'2.5GY', '5GY', '7.5GY', '10GY',...
'2.5G', '5G', '7.5G', '10G',...
'2.5BG', '5BG', '7.5BG', '10BG',...
'2.5B', '5B', '7.5B', '10B',...
'2.5PB', '5PB', '7.5PB', '10PB',...
'2.5P', '5P', '7.5P', '10P',...
'2.5RP', '5RP', '7.5RP', '10RP',...
'N'};
fid = fopen('ExtrapolatedMunsellRenotation.txt', 'r');
% Read through and ignore the description at the start of the file.
% The line 'DESCRIPTION ENDS HERE' has been added to the file, to
% indicate when the description ends.
FileLine = fgetl(fid);
while strcmp(FileLine, 'DESCRIPTION ENDS HERE') == false
FileLine = fgetl(fid);
end
% Read through line with headings, and leading space of second line
for i = 1:6
blankspace = fscanf(fid,'%s',1);
end
% Each loop iteration reads a line of renotation data,
% and enters it into renotation matrices
linectr = 0;
while ~feof(fid)
% Read in Munsell coordinates, and xyY coordinates
linectr = linectr + 1;
HStr = fscanf(fid,'%s',1);
VStr = fscanf(fid,'%s',1);
CStr = fscanf(fid,'%s',1);
xStr = fscanf(fid,'%s',1);
yStr = fscanf(fid,'%s',1);
YStr = fscanf(fid,'%s',1);
% Determine matrix indices for data just read in
for i = 1:length(HueList)
if strcmp(HStr,HueList{i}) == 1
HueIndex = i;
end
end
ValueIndex = str2num(VStr);
ChromaIndex = str2num(CStr)/2;
if abs(ValueIndex - round(ValueIndex)) < 0.001 % Only record entries with integer values
% Enter data into appropriate matrix cells
xRen(HueIndex, ValueIndex, ChromaIndex) = str2num(xStr);
yRen(HueIndex, ValueIndex, ChromaIndex) = str2num(yStr);
YRen(HueIndex, ValueIndex, ChromaIndex) = str2num(YStr);
end
end
fclose(fid);
disp(['number of colours read from file: ',num2str(linectr)]);
% Fill renotation matrices for greys. The reflectance percentages for the
% nine integer values are taken from Table II of [Newhall1943].
RenotationPercentages = [1.210, 3.126, 6.555, 12.00, 19.77, 30.05, 43.06, 59.10, 78.66];
for MunsellValue = 1:9 % Loop over nine grey values
RenotationPercentage = RenotationPercentages(MunsellValue);
% In the Munsell renotation, the xy coordinates of neutral greys are taken to be
% the xy coordinates of Illuminant C
[xRen(41,MunsellValue,20) yRen(41,MunsellValue,20)] = roo2xy(ones(size([400:10:700])), 'C/2', [400:10:700]);
% The following line was replaced Jan. 1, 2014 by the line above, by Paul Centore
% [xRen(41,MunsellValue,20) yRen(41,MunsellValue,20)] = IlluminantCWhitePoint();
YRen(41,MunsellValue,20) = RenotationPercentage;
end
% Save three matrices as fields of one structure, and save that structure
% as a .mat file.
ExtrapolatedRenotationMatrices.x = xRen;
ExtrapolatedRenotationMatrices.y = yRen;
ExtrapolatedRenotationMatrices.Y = YRen;
save ExtrapolatedRenotationMatrices.mat ExtrapolatedRenotationMatrices;