slow rendering of 2K arrays using imshow in

Hi all,

I recently bumped into a problem while trying to display imshow images (2048x2048 pix) in a GUI based on TkAgg (matplotib0.91.2, python 2.4.4, numpy1.0.4). In brief, building the image with imshow is Ok, but the call to show() or draw() takes about 1.2 s on my system (XP, 2.8Ghz, 2Go ram). After reading a lot of posts and trying out a few things, I turned to the example and modified it accordingly (code attached below). In the end, the display is still not much faster using this method (still in the order of 1.2 s as indicated by the result below).
Could any one tel me whether I’m doing something wrong ?

As far as I understand, at least in my Tk GUI, the limiting step using the ImageTk.FigureCanvasTkAgg is the call to draw() or draw_artist(). I
read some comments from John regarding TkAgg being slow in some cases but couldn’t find a definite answer.

Any hint would be much appreciated…




For detailed comments on animation and the techniqes used here, see

the wiki entry

import matplotlib

import sys
import pylab as p
#import matplotlib.numerix as nx
import time

from FileUtils10 import fileHandling

for profiling

tstart = time.time()
tprevious = time.time()

fnamelist = [‘fname1’,‘fname2’,‘fname3’]

ax = p.subplot(111)
canvas = ax.figure.canvas

print 't1 ',time.time()-tprevious
tprevious = time.time()

create the initial line

dataarr = fileHandling(fnamelist[0]).readSpecial()
#print dataarr.dtype => numpy dtype uint16
#dataarr =
print 't2 ',time.time()-tprevious
tprevious = time.time()

image = p.imshow(dataarr, animated=True)
print 't3 ',time.time()-tprevious
tprevious = time.time()

def run(*args):
tprevious = time.time()
background = canvas.copy_from_bbox(ax.bbox)
print 't4 ',time.time()-tprevious
tprevious = time.time()
while 1:
#print fnamelist[run.cnt]
# restore the clean slate background
print 't5 ',time.time()-tprevious
tprevious = time.time()
# update the data
dataarr = fileHandling(fnamelist[run.cnt]).readSpecial()
print 't6 ',time.time()-tprevious
tprevious = time.time()
print 't7 ',time.time()-tprevious
tprevious = time.time()
# just draw the animated artist
print 't8 ',time.time()-tprevious
tprevious = time.time()
# just redraw the axes rectangle
print 't9 ',time.time()-tprevious
tprevious = time.time()

    if fnamelist[run.cnt] == fnamelist[-1]:
        # print the timing info and quit
        print 'total time:' , time.time()-tstart
        print 'FPS:' , 1000./(time.time()-tstart)


    run.cnt += 1

run.cnt = 0

p.subplots_adjust(left=0.3, bottom=0.3) # check for flipy bugs
p.grid() # to ensure proper background restore
manager = p.get_current_fig_manager()
manager.window.after(100, run)

Results in:

t1 0.858999967575
t3 1.31299996376
t4 0.0
t5 0.0
t6 0.0310001373291
t7 0.0
t8 1.18700003624
t9 0.0160000324249
t5 0.0
t6 0.0469999313354
t7 0.0
t8 1.17200016975
t9 0.0149998664856
t5 0…0
t6 0.047000169754
t7 0.0
t8 1.21899986267
t9 0.0
t5 0.0
t6 0.0460000038147
t7 0.0
t8 1.17199993134
t9 0.0
t5 0.0
t6 0.0469999313354
t7 0.0
t8 1.18700003624
t9 0.0160000324249
total time: 8.75
FPS: 114.285714286