I am experimenting with numpy masked arrays, and have a question about how imshow handles them: from numpy import ma from pylab import colorbar, imshow, show a=ma.array([[1,2,3],[4,5,6]],mask=[[0,0,1],[0,0,0]], fill_value=0) imshow(a, interpolation='nearest') colorbar() show() With svn matplotlib, the missing value is treated as if identical to the maximum value. I thought imshow would instead respect the masked array's fill_value property by calling fix_invalid, and perhaps defaulting to the min() or max() if fill_value is the default 999999. What is the intended behavior? Relatedly, it looks like imshow and other functions like contour are badly confused by NaNs, I thought they were supported? Thanks, Darren