how to extract rgb color image from surface height colormap

Asked by Itzik Ben Shabat on 11 Mar 2015

Latest activity Commented on by Itzik Ben Shabat on 11 Mar 2015

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Hi all, I wrote the code attached below. what i wish to do now (and not sure how) is create an RGB image from the colors that are defined by the Z values. so lets say that in the given example the color at each point will translate to a pixel then i will have a 61X61 RGB color image. how can i do that ?

[X,Y] = meshgrid(-3:0.1:3,-3:0.1:3);
Z=peaks(X,Y);
%Geneating the colors for the colormap
colors=[0,0.6,1;
            0,0.6,1;
            0.95,0.95,0.95;
            0.953,0.64,0.375;
            0,1,0;
            1,1,1;
            1,1,1];
colors_number=size(colors,1);
colors_interp = interp1(1:colors_number,colors,1:0.1:colors_number);    
% Draw the surface
h=surf(X,Y,Z,'edgecolor','none');
colormap(colors_interp);

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Answer by Guillaume on 11 Mar 2015

Accepted Answer

See the tip section of caxis for an explanation of how matlab maps the Z values to a colour map index. So:

   mapbounds = caxis;
   numcolours = size(colors_interp, 1);
   mapindex = fix((Z-mapbounds(1)) / (mapbounds(2) - mapbounds(1)) * numcolours) + 1;
   mapindex(mapindex < 1) = 1;
   mapindex(mapindex > numcolours) = numcolours;
   img = ind2rgb(mapindex, colors_interp);
   imshow(img);

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Itzik Ben Shabat on 11 Mar 2015

thank you ! ! !

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