function cmap=isolum(n,varargin)
%ISOLUM Isoluminant-Colormap compatible with red-green color perception deficiencies
%
% Written by Matthias Geissbuehler - matthias.geissbuehler@a3.epfl.ch
% January 2013
%
% Features:
% 1) All colors have the same luminescence (ideal for lifetime
% images that will be displayed with an additional transparency map
% to "mask" places where the lifetime is not well defined)
% 2) Color vision deficient persons can only see reduced color: as much
% as 10% of adult male persons have a red-green defiency (either
% Deuteranope or Protanope) -> as a result they can only distinguish
% between blue and yellow. A colormap which is "save" for color vision
% deficient persons is hence only based on these colors.
% However: people with normal vision DO have a larger space of colors
% available: it would be a pity to discard this freedom. So the goal
% must be a colormap that is both using as many colors as possible
% for normal-sighted people as well as a colormap that will "look"
% blue-yellow to people with colorblindness without transitions that
% falsify the information by including a non-distinct transitions
% (as is the case for many colormaps based on the whole spectrum
% (ex. rainbow or jet).
% That's what this colormap here tries to achieve.
% 3) In order to be save for publications, the colormap uses colors that
% are only from the CMYK colorspace (or at least not too far)
%
%
% See also: ametrine, morgenstemning
%
%
% Please feel free to use this colormap at your own convenience.
% A citation to the original article is of course appreciated, however not "mandatory" :-)
%
% M. Geissbuehler and T. Lasser "How to display data by color schemes compatible
% with red-green color perception deficiencies" Opt. Express 21, 9862-9874 (2013)
% http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-21-8-9862
%
%
% For more detailed information, please see:
% http://lob.epfl.ch -> Research -> Color maps
%
%
% Usage:
% cmap = isolum(n)
%
% All arguments are optional:
%
% n The number of elements (256)
%
% Further on, the following options can be applied
% 'gamma' The gamma of the monitor to be used (1.8)
% 'minColor' The absolute minimum value can have a different color
% ('none'), 'white','black','lightgray', 'darkgray'
% or any RGB value ex: [0 1 0]
% 'maxColor' The absolute maximum value can have a different color
% 'invert' (0), 1=invert the whole colormap
%
% Examples:
% figure; imagesc(peaks(200));
% colormap(isolum)
% colorbar
%
% figure; imagesc(peaks(200));
% colormap(isolum(256,'gamma',1.8,'minColor','black','maxColor',[0 1 0]))
% colorbar
%
% figure; imagesc(peaks(200));
% colormap(isolum(256,'invert',1,'minColor','white'))
% colorbar
%
%
%
%
%
%
% Copyright (c) 2013, Matthias Geissbuehler
% All rights reserved.
%
% Redistribution and use in source and binary forms, with or without
% modification, are permitted provided that the following conditions are
% met:
%
% * Redistributions of source code must retain the above copyright
% notice, this list of conditions and the following disclaimer.
% * Redistributions in binary form must reproduce the above copyright
% notice, this list of conditions and the following disclaimer in
% the documentation and/or other materials provided with the distribution
%
% THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
% AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
% IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
% ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
% LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
% CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
% SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
% INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
% CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
% ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
% POSSIBILITY OF SUCH DAMAGE.
% Copyright 2013 Matthias Geissbuehler - matthias.geissbuehler@a3.epfl.ch
% $Revision: 3.0 $ $Date: 2013/01/29 12:00:00 $
p=inputParser;
p.addParamValue('gamma',1.8, @(x)x>0);
p.addParamValue('minColor','none');
p.addParamValue('maxColor','none');
p.addParamValue('invert',0, @(x)x==0 || x==1);
if nargin==1
p.addRequired('n', @(x)x>0 && mod(x,1)==0);
p.parse(n);
elseif nargin>1
p.addRequired('n', @(x)x>0 && mod(x,1)==0);
p.parse(n, varargin{:});
else
p.addParamValue('n',256, @(x)x>0 && mod(x,1)==0);
p.parse();
end
config = p.Results;
n=config.n;
%the ControlPoints and the spacing between them
%the ControlPoints in a very isoluminescence case
cP(:,1) = [90 190 245]./255; k(1)=1; %cyan at index 1
cP(:,2) = [157 157 200]./255; k(2)=16; %purple at index 16
cP(:,3) = [220 150 130]./255; k(3)=32; %purple at index 32
cP(:,4) = [245 120 80 ]./255; k(4)=43; %redish at index 43
cP(:,5) = [180 180 0 ]./255; k(5)=64; %yellow at index 64
% Making them strictly isoluminescent
tempgraymap = mean((cP).^config.gamma,1);
tempgraymap = tempgraymap .^(1/config.gamma);
cP(1,:)=cP(1,:)./tempgraymap.*mean(tempgraymap);
cP(2,:)=cP(2,:)./tempgraymap.*mean(tempgraymap);
cP(3,:)=cP(3,:)./tempgraymap.*mean(tempgraymap);
for i=1:4 % interpolation between control points, while keeping the luminescence constant
f{i} = linspace(0,1,(k(i+1)-k(i)+1))'; % linear space between these controlpoints
ind{i} = linspace(k(i),k(i+1),(k(i+1)-k(i)+1))';
cmap(ind{i},1) = ((1-f{i})*cP(1,i)^config.gamma + f{i}*cP(1,i+1)^config.gamma).^(1/config.gamma);
cmap(ind{i},2) = ((1-f{i})*cP(2,i)^config.gamma + f{i}*cP(2,i+1)^config.gamma).^(1/config.gamma);
cmap(ind{i},3) = ((1-f{i})*cP(3,i)^config.gamma + f{i}*cP(3,i+1)^config.gamma).^(1/config.gamma);
end
% normal linear interpolation to achieve the required number of points for the colormap
cmap = abs(interp1(linspace(0,1,size(cmap,1)),cmap,linspace(0,1,n)));
if config.invert
cmap = flipud(cmap);
end
if ischar(config.minColor)
if ~strcmp(config.minColor,'none')
switch config.minColor
case 'white'
cmap(1,:) = [1 1 1];
case 'black'
cmap(1,:) = [0 0 0];
case 'lightgray'
cmap(1,:) = [0.8 0.8 0.8];
case 'darkgray'
cmap(1,:) = [0.2 0.2 0.2];
end
end
else
cmap(1,:) = config.minColor;
end
if ischar(config.maxColor)
if ~strcmp(config.maxColor,'none')
switch config.maxColor
case 'white'
cmap(end,:) = [1 1 1];
case 'black'
cmap(end,:) = [0 0 0];
case 'lightgray'
cmap(end,:) = [0.8 0.8 0.8];
case 'darkgray'
cmap(end,:) = [0.2 0.2 0.2];
end
end
else
cmap(end,:) = config.maxColor;
end
