In [1]: import matplotlibIn [2]: matplotlib.__version__Out[2]: '1.2.0'In [3]: from matplotlib import pyplot as pltIn [4]: fig = plt.figure()In [5]: ax = fig.add_subplot(1,1,1)In [6]: import numpy as npIn [7]: ax.imshow(np.zeros((128, 128)))Out[7]: <matplotlib.image.AxesImage at 0x105085ed0>In [8]: fig.savefig('test.ps')---------------------------------------------------------------------------TypeError                                 Traceback (most recent call last)<ipython-input-8-d877e517da66> in <module>()----> 1 fig.savefig('test.ps')/opt/local/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/site-packages/matplotlib/figure.py in savefig(self, *args, **kwargs)   1362             kwargs.setdefault('edgecolor', rcParams['savefig.edgecolor'])   1363 -> 1364         self.canvas.print_figure(*args, **kwargs)   1365    1366         if transparent:/opt/local/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/site-packages/matplotlib/backend_bases.py in print_figure(self, filename, dpi, facecolor, edgecolor, orientation, format, **kwargs)   2091                 orientation=orientation,   2092                 bbox_inches_restore=_bbox_inches_restore,-> 2093                 **kwargs)   2094         finally:   2095             if bbox_inches and restore_bbox:/opt/local/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/site-packages/matplotlib/backend_bases.py in print_ps(self, *args, **kwargs)   1858         from .backends.backend_ps import FigureCanvasPS # lazy import   1859         ps = self.switch_backends(FigureCanvasPS)-> 1860         return ps.print_ps(*args, **kwargs)   1861    1862     def print_raw(self, *args, **kwargs):/opt/local/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/site-packages/matplotlib/backends/backend_ps.py in print_ps(self, outfile, *args, **kwargs)    969     970     def print_ps(self, outfile, *args, **kwargs):--> 971         return self._print_ps(outfile, 'ps', *args, **kwargs)    972     973     def print_eps(self, outfile, *args, **kwargs):/opt/local/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/site-packages/matplotlib/backends/backend_ps.py in _print_ps(self, outfile, format, *args, **kwargs)   1005             self._print_figure(outfile, format, imagedpi, facecolor, edgecolor,   1006                                orientation, isLandscape, papertype,-> 1007                                **kwargs)   1008    1009     def _print_figure(self, outfile, format, dpi=72, facecolor='w', edgecolor='w',/opt/local/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/site-packages/matplotlib/backends/backend_ps.py in _print_figure(self, outfile, format, dpi, facecolor, edgecolor, orientation, isLandscape, papertype, **kwargs)   1098             bbox_inches_restore=_bbox_inches_restore)   1099 -> 1100         self.figure.draw(renderer)   1101    1102         if dryrun: # return immediately if dryrun (tightbbox=True)/opt/local/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/site-packages/matplotlib/artist.py in draw_wrapper(artist, renderer, *args, **kwargs)     53     def draw_wrapper(artist, renderer, *args, **kwargs):     54         before(artist, renderer)---> 55         draw(artist, renderer, *args, **kwargs)     56         after(artist, renderer)     57 /opt/local/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/site-packages/matplotlib/figure.py in draw(self, renderer)    998         dsu.sort(key=itemgetter(0))    999         for zorder, a, func, args in dsu:-> 1000             func(*args)   1001    1002         renderer.close_group('figure')/opt/local/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/site-packages/matplotlib/artist.py in draw_wrapper(artist, renderer, *args, **kwargs)     53     def draw_wrapper(artist, renderer, *args, **kwargs):     54         before(artist, renderer)---> 55         draw(artist, renderer, *args, **kwargs)     56         after(artist, renderer)     57 /opt/local/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/site-packages/matplotlib/axes.py in draw(self, renderer, inframe)   2086    2087         for zorder, a in dsu:-> 2088             a.draw(renderer)   2089    2090         renderer.close_group('axes')/opt/local/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/site-packages/matplotlib/artist.py in draw_wrapper(artist, renderer, *args, **kwargs)     53     def draw_wrapper(artist, renderer, *args, **kwargs):     54         before(artist, renderer)---> 55         draw(artist, renderer, *args, **kwargs)     56         after(artist, renderer)     57 /opt/local/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/site-packages/matplotlib/image.py in draw(self, renderer, *args, **kwargs)    364             im._url = self.get_url()    365             im._gid = self.get_gid()--> 366             renderer.draw_image(gc, l, b, im)    367         gc.restore()    368 /opt/local/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/site-packages/matplotlib/backends/backend_ps.py in draw_image(self, gc, x, y, im, dx, dy, transform)    470     471         h, w, bits, imagecmd = self._get_image_h_w_bits_command(im)--> 472         hexlines = '\n'.join(self._hex_lines(bits))    473     474         if dx is None:TypeError: sequence item 0: expected str instance, bytes found