How to generate a non-linear colormap/colorbar?

Question

I would like to show a non-uniform colorbar as in the first picture. I have tried the code below. \'mycamp4\' is a colormap manually saved. The result is shown as the second

Answer 1

You can customize the colormap and the ticks in the colorbar, but the colorbar itself is based on linear intervals and you can't change that.

There's a workaround though.

lets say you want your colorbar like that in picture 1 with N nonlinear intervals (e.g. color_limits = [1 2 20], if N=2). you have to:

1) define another variable for your data. e.g.

data2 = nan(size(data));
for i=1:N
   b = data>color_limits(i) & data>=color_limits(i+1);
   data2(b) = i-0.5;
end

Basically you are binning data, using the intervals in color_limits, into a different variable data2 that you will display

2) make your image of data2

3) define the colorbar limits: caxis([0 N])

4) define a colormap with N colors, e.g. colormap(jet(N))

5) customize the ticks in the colorbar