Re: [Matplotlib-users] Trouble with imshow

[Benjamin R. <ben...@ou...>]

On Wed, Feb 2, 2011 at 5:33 PM, Robert Abiad <ab...@ss...> wrote:

> Hello All,
>
> I'm very new to python, so bear with me.
>
> I'd like to use python to do my image processing, but I'm running into
> behavior that doesn't make
> sense to me.  I'm using Windows 7 Pro (64-bit) with 4 gigs of memory,
> python 2.6.6, and the newest
> versions of ipython, pyfits, matplotlib (1.0.1), numpy (1.5.1), scipy.  I'm
> loading in a fits file
> that's 26 MB (~16 Mpixels).  When I load my image in ImageJ, I can see
> memory usage go up by 50MB,
> but when I try displaying the image using imshow(), my memory usage goes up
> by around 500MB, each
> time.  If I close the figure and replot it, imshow() crashes.  I don't know
> if I'm doing something
> wrong, or if it's a new or known bug.  I tried the same thing on Linux and
> got the same result.
> Here's a transcript.
>
>   Welcome to pylab, a matplotlib-based Python environment.
>   For more information, type 'help(pylab)'.
>
> In [1]: import pyfits
>
> In [2]: from Tkinter import *
>
> In [3]: import tkFileDialog
>
> In [4]: image=pyfits.getdata(tkFileDialog.askopenfilename())
>
> In [5]: imshow(image)
> Out[5]: <matplotlib.image.AxesImage object at 0x03BCA170>
>
> In [6]: close()
>
> In [7]: imshow(image,origin='lower')
> Out[7]: <matplotlib.image.AxesImage object at 0x0440E170>
>
> In [8]: close()
>
> In [9]: imshow(image[100:3600,100:3600],origin='lower')
> Out[9]: <matplotlib.image.AxesImage object at 0x045D9FB0>
>
> In [10]: Exception in Tkinter callback
> Traceback (most recent call last):
>   File "C:\app\Python2.6\lib\lib-tk\Tkinter.py", line 1410, in __call__
>     return self.func(*args)
>   File "C:\app\Python2.6\lib\lib-tk\Tkinter.py", line 495, in callit
>     func(*args)
>   File
> "C:\app\Python2.6\lib\site-packages\matplotlib\backends\backend_tkagg.py",
> line 263, in
> idle_draw
>     self.draw()
>   File
> "C:\app\Python2.6\lib\site-packages\matplotlib\backends\backend_tkagg.py",
> line 248, in draw
>     FigureCanvasAgg.draw(self)
>   File
> "C:\app\Python2.6\lib\site-packages\matplotlib\backends\backend_agg.py",
> line 394, in draw
>     self.figure.draw(self.renderer)
>   File "C:\app\Python2.6\lib\site-packages\matplotlib\artist.py", line 55,
> in draw_wrapper
>     draw(artist, renderer, *args, **kwargs)
>   File "C:\app\Python2.6\lib\site-packages\matplotlib\figure.py", line 798,
> in draw
>     func(*args)
>   File "C:\app\Python2.6\lib\site-packages\matplotlib\artist.py", line 55,
> in draw_wrapper
>     draw(artist, renderer, *args, **kwargs)
>   File "C:\app\Python2.6\lib\site-packages\matplotlib\axes.py", line 1946,
> in draw
>     a.draw(renderer)
>   File "C:\app\Python2.6\lib\site-packages\matplotlib\artist.py", line 55,
> in draw_wrapper
>     draw(artist, renderer, *args, **kwargs)
>   File "C:\app\Python2.6\lib\site-packages\matplotlib\image.py", line 354,
> in draw
>     im = self.make_image(renderer.get_image_magnification())
>   File "C:\app\Python2.6\lib\site-packages\matplotlib\image.py", line 569,
> in make_image
>     transformed_viewLim)
>   File "C:\app\Python2.6\lib\site-packages\matplotlib\image.py", line 201,
> in _get_unsampled_image
>     x = self.to_rgba(self._A, self._alpha)
>   File "C:\app\Python2.6\lib\site-packages\matplotlib\cm.py", line 193, in
> to_rgba
>     x = self.norm(x)
>   File "C:\app\Python2.6\lib\site-packages\matplotlib\colors.py", line 820,
> in __call__
>     result = (val-vmin) / (vmax-vmin)
>   File "C:\app\Python2.6\lib\site-packages\numpy\ma\core.py", line 3673, in
> __div__
>     return divide(self, other)
>   File "C:\app\Python2.6\lib\site-packages\numpy\ma\core.py", line 1077, in
> __call__
>     m |= filled(domain(da, db), True)
>   File "C:\app\Python2.6\lib\site-packages\numpy\ma\core.py", line 772, in
> __call__
>     return umath.absolute(a) * self.tolerance >= umath.absolute(b)
> MemoryError
>
>
> Thanks for any help,
> -robert
>
>
This isn't new, but it isn't well understood either:

http://www.mail-archive.com/mat...@li.../msg19614.html

Unfortunately, that conversation went off-list, and never resulted in a bug
report being filed.  Could you please file a bug report on this?

http://sourceforge.net/tracker/?group_id=80706

Thanks,
Ben Root