Assigning black color to zero values of "imagesc" plot
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I want to use "imagesc" to plot the following matrix:
A=[9 24 6 12 6;
0 33 24 0 12;
0 0 13 14 12;
0 0 0 0 0];
I want to assign black color to 0 values and set the color bar from 6 to 33.
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Image Analyst
am 24 Sep. 2013
Try this:
A=[9 24 6 12 6;
0 33 24 0 12;
0 0 13 14 12;
0 0 0 0 0];
imagesc(A);
cmap = jet(max(A(:)));
% Make values 0-5 black:
cmap(1:6,:) = zeros(6,3);
colormap(cmap);
colorbar
2 Kommentare
Image Analyst
am 25 Sep. 2013
A=[9 9.1 8.3 0 0;
0 9.5 8.4 0 0;
0 0 9.6 8.3 8.1;
0 0 0 9.7 0];
lowestValue = min(A(A(:)>0))
highestValue = max(A(:))
imagesc(A);
cmap = jet(256);
colormap(cmap);
caxis(gca,[lowestValue-2/256, highestValue]);
% Make less than lowest value black:
cmap(1,:)=[0,0,0];
colormap(cmap)
colorbar
Weitere Antworten (1)
Kelly Kearney
am 24 Sep. 2013
It'll be a little tricky to do with imagesc, but you could get a similar result with pcolor:
aplt = nan(size(A)+1);
aplt(1:end-1,1:end-1) = A;
aplt(aplt == 0) = NaN;
pcolor(aplt);
colorbar;
set(gca, 'color', 'k', 'clim', [6 33], 'ydir', 'reverse')
2 Kommentare
Kelly Kearney
am 25 Sep. 2013
Neither function does any smoothing, unless you use interpolated shading with the pcolor plot. If you're referring to the black outlines of each grid cell that is the default under pcolor, you can alter that with a simple
shading flat;
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