Fix links to NumPy project
@@ -202,10 +202,12 @@ integers less than 4, because the image has a bit depth of 2.
NumPy
-----
-`NumPy <http://numpy.scipy.org/>`_ is a package for scientific computing with Python. It is not part
+`NumPy <http://www.numpy.org/>`_ is a package for scientific computing with Python.
+It is not part
of a standard Python installation, it is
-`downloaded and installed separately <http://sourceforge.net/project/showfiles.php?group_id=1369&package_id=175103>`_
-if needed. Numpy's array manipulation facilities make it good for doing
+`downloaded and installed separately <https://pypi.org/project/numpy/>`_
+if needed.
+Numpy's array manipulation facilities make it good for doing
certain type of image processing, and scientific users of NumPy may wish
to output PNG files for visualisation.
