libpng version incompatibility in fresh installation of IPython

Question

I used this guide to install the "scientific stack" for Python (OSX 10.9.2, brewed Python 2.7.6, IPython 2.0, matplotlib 1.3.1, libpng 1.6.10). Everything was looking good.

However, trying to run a simple plot in IPython's notebook environment with --pylab=inline gives me this error:

/usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/IPython/core/formatters.py:239: FormatterWarning: Exception in image/png formatter: Could not create write struct FormatterWarning,

And in the terminal it says: libpng warning: Application built with libpng-1.5.17 but running with 1.6.10

I have no other libpng installed as far as I can tell. I tried deleting all files beginning with libpng from /usr/local/ and reinstalling everything, to no avail. The output from building matplotlib (pip install matplotlib) contains:

BUILDING MATPLOTLIB
            matplotlib: yes [1.3.1]
                python: yes [2.7.6 (default, Mar 16 2014, 15:04:47)  [GCC
                        4.2.1 Compatible Apple LLVM 5.1 (clang-503.0.38)]]
              platform: yes [darwin]

REQUIRED DEPENDENCIES AND EXTENSIONS
                 numpy: yes [version 1.8.1]
              dateutil: yes [using dateutil version 2.2]
               tornado: yes [using tornado version 3.2]
             pyparsing: yes [using pyparsing version 2.0.1]
                 pycxx: yes [Couldn't import.  Using local copy.]
                libagg: yes [pkg-config information for 'libagg' could not
                        be found. Using local copy.]
              freetype: yes [version 17.2.11]
                   png: yes [version 1.6.10]

OPTIONAL SUBPACKAGES
           sample_data: yes [installing]
              toolkits: yes [installing]
                 tests: yes [using nose version 1.3.1]

OPTIONAL BACKEND EXTENSIONS
                macosx: yes [installing, darwin]
                qt4agg: yes [installing, Qt: 4.8.6, PyQt4: 4.10.4]
               gtk3agg: no  [Requires pygobject to be installed.]
             gtk3cairo: no  [Requires cairo to be installed.]
                gtkagg: no  [Requires pygtk]
                 tkagg: yes [installing, version 81008]
                 wxagg: no  [requires wxPython]
                   gtk: no  [Requires pygtk]
                   agg: yes [installing]
                 cairo: no  [cairo not found]
             windowing: no  [Microsoft Windows only]

OPTIONAL LATEX DEPENDENCIES
                dvipng: no
           ghostscript: no
                 latex: no
               pdftops: no

So it seems to me matplotlib should be compiled against libpng 1.6.10? Can someone help me figure out what's going on?

Answer 1

An expansion of the answer provided by @glenn-randers-pehrson:

pip uninstall matplotlib
cd /opt/X11/include/libpng15
mv png.h _png.h
mv pngconf.h _pngconf.h
mv pnglibconf.h _pnglibconf.h
pip install matplotlib
(if needed remove the old directory or use the force option)

(now move the .h files back to their original locations)

Answer 2

Look for old header files beginning with "png" (png.h, pngconf.h, perhaps others) and remove them.