Changing colorscale increments on a surface plot
31 views (last 30 days)
Show older comments
I've got some data which ranges from 1 to around 1E-06 which I am plotting using the mesh function. I'm using the jet colormap which is fine but the color scales goes from 1 to 0.1 in steps of 0.1 and I want it go from 1 to 1E-09 or so in increments of one order of magnitude. i.e. colorscale goes, 1, 0.1, 0.01, 0.001, 1E-04 etc. This will give a broad range of color data and should be fairly intuitive to interpret, currently my surface is nearly all blue as it is not scaling the color.
Some googling suggesting using the set command, but I've not had any success.
I tried:
mesh(X,Y,Z) view(2)
aa = colorbar;
get(aa,'Ytick');
%This returns a vector of [0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1]
%So then if we create a vector tt, with the desired YTick
tt = [1e-10,1e-09,1e-08,1e-07,1e-06,1e-05,1e-04,1e-03,1e-02,1e-01,1]
set(aa,'Ytick',tt);
But this doesn't appear to do anything, the colors on the graph stay the same. Any help which could set me on the right track would be greatly appreciated.
Thanks in advance Rob
0 Comments
Accepted Answer
Mike Garrity
on 24 Sep 2014
I'm afraid that the colormap is always applied as a linear function of the CData. Changing the ticks on the colorbar doesn't change anything about how the colormap is applied, it just changes the values which are displayed on the colorbar.
You've really got two options here.
One is to make your CData be a transformed version of your ZData
C = log10(Z);
mesh(X,Y,Z,C)
The other is to transform the colors in your colormap like so:
ncolorsin = 2048;
ncolorsout = 128;
c = jet(ncolorsin); % Get a big copy of jet
t = linspace(0,1,ncolorsout); % Create a linear ramp the size of the colormap we actually want
t2 = t.^10; % Apply whatever transform you like to the ramp
% Use that to scale the big linear colormap into the small stretched one.
c2 = c(1+floor((ncolorsin-1)*t2'),:);
colormap(c2); % Use that as the colormap
Both approaches have advantages and disadvantages.
3 Comments
Enrico Aymerich
on 1 Dec 2020
Edited: Enrico Aymerich
on 1 Dec 2020
Actually, the second option is also good, but if the transform is t.^10 the image tends to be saturated to low values (as Rob commented). It seems to work better with t2 = sqrt(t) or similar. I had a similar issue
More Answers (1)
Image Analyst
on 23 Sep 2014
You can get up to 256 colors in a colormap
colormap(jet(256));
the default, which you're probably seeing is only 64.
3 Comments
Image Analyst
on 24 Sep 2014
Not exactly sure what that means, but have you checked out the caxis() function?
See Also
Categories
Find more on Colormaps in Help Center and File Exchange
Products
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!