[Matplotlib-users] Is really matplotlib this slooow for displaying images ? (sorry again)

[Eric E. <ems...@ob...>]

Hi,

after some successful attempt at migrating routines from several plotting
and/or analysing softwares (pgplot, Midas, Iraf, etc) to Matplotlib
I now hit a big wall: the speed at which it can display a reasonably 
large image:

- I have  a ''local'' library to read fits files [2D images] in python 
(after SWIG wrapping).
It converts these files into float - nmerix - arrays. I was then testing 
the ability
of matplotlib to display these 2D arrays.
Until now all was fine since I tested matplotlib on very small images 
(50x50 pixels).

Yesterday I tried with a 1600x1600 pixels image. NOTE: this is a very 
reasonable
size (and typical) in my work and I expect much much bigger ones in a 
near future
(up to 20 000 x 20 000).

==> Matplotlib takes ~20 seconds to display it !!!
  (after 12 seconds the window opens, and then it takes
  another 8 seconds to be displayed)

(as compared to less than .2 sec for Midas, Iraf and others so a factor 
of 100 at least!!!
 and less than a second using the ppgplot routines).

Some info:

running on a 1.6 Ghz/512 RAM  centrino, linux, backend TkAgg, numarray, 
float array of 1600x1600 pixels.
Using either imshow or figimage in ''ipython -pylab'' (tried different 
interpolation schemes
the one I want being ''nearest'' in general)

To be frank, this is a killer for me, since I need to work on such images
(signal processing, analysing) and display them each time changing the
levels, centring etc etc. There is no way I will wait for 1 mn for 3 
successive displays...

So the question now:
- am I doing something wrong (backend, way to load the array, ...) or is it
  intrinsic to matplotlib ?
- is there a way out? (basically the same question..)

If there is no way out, I may have to just abandon (sigh) matplotlib for 
displaying images.
But if there is one, please let me know!!

Thanks

Eric

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