Black mask over pcolor plot

I have two matrices of the same size. The first one is function of two variables, which is to be displayed using pcolor. But then I need to mask (paint with black) part of this plot using the mask defined by the second matrix (zeros for transparent cells, ones for those to be masked). I need the colorbar and caxis to remain from the main pcolor of the function. How can I do this? I suspect this is something to do with AlphaData property of the second graph, but so far I only see the solutions for imshow, but not for pcolor.

Answer 1

[J. Alex Lee]

You can assign NaN in your first matrix according to your mask and set the background of your axes to black:

A = randi(255,200,200);
B = false(200,200);
B(20:30,60:80) = true;

A(B) = NaN;

pcolor(A)
set(gca,'Color','k')

Answer 2

[Image Analyst]

An example of what you'd like to see would be good. In the meantime, check out patch() and fill().