Library not loaded: /usr/local/lib/libpng15.15.dylib upon %matplotlib qt -> solution -> brew reinstall libpng qt

%matplotlib qt

---------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)
<ipython-input-1-6ad73d0e50c7> in <module>()
----> 1 get_ipython().magic(u'matplotlib qt')

/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/IPython/core/interactiveshell.pyc in magic(self, arg_s)
   2203         magic_name, _, magic_arg_s = arg_s.partition(' ')
   2204         magic_name = magic_name.lstrip(prefilter.ESC_MAGIC)
-> 2205         return self.run_line_magic(magic_name, magic_arg_s)
   2206 
   2207     #-------------------------------------------------------------------------

/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/IPython/core/interactiveshell.pyc in run_line_magic(self, magic_name, line)
   2124                 kwargs['local_ns'] = sys._getframe(stack_depth).f_locals
   2125             with self.builtin_trap:
-> 2126                 result = fn(*args,**kwargs)
   2127             return result
   2128 

/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/IPython/core/magics/pylab.pyc in matplotlib(self, line)

/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/IPython/core/magic.pyc in <lambda>(f, *a, **k)
    191     # but it's overkill for just that one bit of state.
    192     def magic_deco(arg):
--> 193         call = lambda f, *a, **k: f(*a, **k)
    194 
    195         if callable(arg):

/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/IPython/core/magics/pylab.pyc in matplotlib(self, line)
     78         """
     79         args = magic_arguments.parse_argstring(self.matplotlib, line)
---> 80         gui, backend = self.shell.enable_matplotlib(args.gui)
     81         self._show_matplotlib_backend(args.gui, backend)
     82 

/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/IPython/core/interactiveshell.pyc in enable_matplotlib(self, gui)
   2941                 gui, backend = pt.find_gui_and_backend(self.pylab_gui_select)
   2942 
-> 2943         pt.activate_matplotlib(backend)
   2944         pt.configure_inline_support(self, backend)
   2945 

/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/IPython/core/pylabtools.pyc in activate_matplotlib(backend)
    285     matplotlib.rcParams['backend'] = backend
    286 
--> 287     import matplotlib.pyplot
    288     matplotlib.pyplot.switch_backend(backend)
    289 

/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/pyplot.py in <module>()
     96 
     97 from matplotlib.backends import pylab_setup
---> 98 _backend_mod, new_figure_manager, draw_if_interactive, _show = pylab_setup()
     99 
    100 

/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/backends/__init__.pyc in pylab_setup()
     26     # imports. 0 means only perform absolute imports.
     27     backend_mod = __import__(backend_name,
---> 28                              globals(),locals(),[backend_name],0)
     29 
     30     # Things we pull in from all backends

/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/backends/backend_qt4agg.py in <module>()
     11 
     12 from backend_agg import FigureCanvasAgg
---> 13 from backend_qt4 import QtCore, QtGui, FigureManagerQT, FigureCanvasQT,\
     14      show, draw_if_interactive, backend_version, \
     15      NavigationToolbar2QT

/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/backends/backend_qt4.py in <module>()
     23     figureoptions = None
     24 
---> 25 from qt4_compat import QtCore, QtGui, _getSaveFileName, __version__
     26 
     27 backend_version = __version__

/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/backends/qt4_compat.py in <module>()
     54             verbose.report(cond+res, 'helpful')
     55 
---> 56     from PyQt4 import QtCore, QtGui
     57 
     58     # Alias PyQt-specific functions for PySide compatibility.

ImportError: dlopen(/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/PyQt4/QtGui.so, 2): Library not loaded: /usr/local/lib/libpng15.15.dylib
  Referenced from: /usr/local/lib/QtGui.framework/Versions/4/QtGui
  Reason: image not found