# How do I create a logarithmic scale colormap or colorbar?

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I need to color 'surf' plots on a log scale and subsequently displace the log-based colorbar.

MathWorks Support Team on 14 May 2020
Edited: MathWorks Support Team on 14 May 2020
Please follow the steps below to create a log colobar in 'surf' plot:
% Plot the surface plot
[X, Y] = meshgrid(1:0.5:10,1:20);
Z = sin(X) + cos(Y);
figure;
surf(X, Y, Z)
% Show the colorbar
colorbar
% Set the log colobar
set(gca,'ColorScale','log')
Note: This feature was introduced in MATLAB R2018a.

#### 1 Comment

Samira Daneshgar on 12 Jan 2017
Hi, I would like to know how can I apply the same thing for the contourf. Thanks,

lvn on 4 May 2018
Strange official answer, since it is clearly possible in Matlab:
set(gca,'ColorScale','log')

sam ira on 8 Oct 2018
I get this error also in R2018a ...
Sanat Kumar Tiwari on 31 Mar 2020
@Ivn, thanks for pointing out simple solution that is working fine. @Walter, your solution also gives similar results but the colorscales need some adjustment for best colorscheme.
It's surprising that official MATLAB answer is "feature not available" !
Walter Roberson on 31 Mar 2020
You can tell by the wording of the official answer that it was written for an older version of MATLAB.

Berthold Reisz on 15 Mar 2019
Try the following:
% let A be your data
A = 100*rand(100,100);
% plot log10 of A
pcolor(log10(A))
% get the minimum and maximum value of A
c1 = min(min(A));
c2 = max(max(A));
% set limits for the caxis
caxis([log10(c1) log10(c2)]);
% preallocate Ticks and TickLabels
num_of_ticks = 5;
Ticks = zeros(1,num_of_ticks);
TickLabels = zeros(1,num_of_ticks);
% distribute Ticks and TickLabels
for n = 1:1:num_of_ticks
Ticks(n) = log10(round(c2)/num_of_ticks*n);
TickLabels(n) = round(c2)/num_of_ticks*n;
end
% set Ticks and TickLabels
colorbar('Ticks',Ticks,'TickLabels',TickLabels)

R2018a

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