Contourf and NaNs (how to make white regions transparent)

Question

I\'m trying to make a contourf plot but certain areas of the data array have NaNs (only in the data matrix, the x and y meshgrid matrices are full). I\'d like these

Answer 1

Would it be an option to use pcolor instead of contourf?

[X Y] = meshgrid(10:50);
Z = X.*Y;
Z(10:30,10:30) = NaN;
figure
imshow(uint8(repmat(1:4:240,[60,1,3])));
hold on;
h = pcolor(X,Y,Z)
set(h,'Edgecolor',  'interp');
colormap jet;