imshow with axes like contour

Thanks. I did not understand the meaning of 'extent'.

    > Another thing I could not find which is probably
    > possible as well: How can I display a label for the
    > colorbar (not ticklabel)?

colorbar returns an Axes instance for the colorbar, so you can use any
of the Axes methods described at

    cax = colorbar()
    cax.set_title('A title')

or if your prefer "setp" style args

    cax = colorbar()
    setp(cax, title='A title', ylabel='ylabel', xlabel='xlabel')