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I have created a colormap that resembles the human connectome project colormap ROY-BIG-BL, doing it manually on the colormap editor see here.

However, I am not able to save this as a colormap. I tried different commands such as 

mycmap = get(gcf,'colormap')

I read that with Matlab 2015 one should use gca, but this gives an error.

Error using matlab.graphics.axis.Axes/get There is no colormap property on the Axes class.

When I then try to use the saved mycmap for another figure, it ignores all modifications und uses the basic colormap parula.

Thanks for help. How can I save it and use it as another colormap in any figure I want?

Robert Seifert
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Markus
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1 Answers1

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The definition of colormaps is deeply hidden inside the figure class, which is not accessible. So you can't save your colormap "with a name" in Matlab and access it like a normal colormap. But a colormap is nothin else than a Yx3 matrix, you can store on disk.

%// custom colormap
n = 50;               %// number of colors
R = linspace(1,0,n);  %// Red from 1 to 0
B = linspace(0,1,n);  %// Blue from 0 to 1
G = zeros(size(R));   %// Green all zero
myCustomColormap = [R(:), G(:), B(:)];

%// save colormap on disk
save('myCustomColormap','myCustomColormap');

%// clear for explanation purposes
clear 
%%%%%%%%%%%%%%%%%%%

%// load colormap saved on disk
load myCustomColormap

%// assign colormap
colormap( myCustomColormap );

You used the colormap editor to create your colormap. After you applied it, use the following code to get the required matrix for further reference:

myCustomColormap = colormap(gca)
save('myCustomColormap','myCustomColormap');

If you want to make the colormap generally available to all your functions, no matter where, add it to your Matlab search path.

Robert Seifert
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  • Thanks that worked perfectly. I integrated the obtained matrix in a m-file like in those https://mathworks.com/matlabcentral/fileexchange/51986-perceptually-uniform-colormaps from Anders Biguri. The colormap is now universally usable. – Markus Jul 09 '17 at 12:34