Re: [Matplotlib-users] Trouble with imshow

[Christoph G. <cg...@uc...>]

On 2/2/2011 3:33 PM, Robert Abiad 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
>


These are previous discussions on the issue:

<http://www.mail-archive.com/mat...@li.../msg14727.html>
<http://www.mail-archive.com/mat...@li.../msg19815.html>
<http://www.mail-archive.com/mat...@li.../msg19614.html>

Christoph