Make imshow more efficent
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I currently have in my code a imshow command, then followed by drawnow. My program is processing data from a acquisition card and then displaying the results in real time. I am trying to do this ~15.3 times per second. But the imshow/drawnow combo is to slow processing wise, and it takes too long so my data acquisition cards memory gets filled, and errors out.
Is there anyway to make it faster?
imshow(-1 * squeeze(Pol1ChanACard1Avg),[],'Parent',imagePlot1, 'border','tight');
imshow(-1 * squeeze(Pol2ChanACard1Avg),[],'Parent',imagePlot2, border','tight');
drawnow;
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Answers (2)
Walter Roberson
on 1 Mar 2013
displaydata = - squeeze(Pol1ChanACard1Avg);
p1 = imshow(displaydata, [], 'Parent', imagePlot1, 'border', 'tight');
p2 = imshow(displaydata, [], 'Parent', imagePlot2, 'border', 'tight');
then in the loop,
displaydata = - squeeze(Pol1ChanACard1Avg);
set(p1, 'CData', displaydata);
set(p2, 'CData', displaydata);
1 Comment
Ian Hunter
on 8 Jun 2019
Thanks!
I need to fullscreen programmatically generated images for a technical application.
I had been using the fullscreen function (https://www.mathworks.com/matlabcentral/fileexchange/11112-fullscreen) .The best time I could get was .03s to refresh the frame. It was very stable, but this was unsatisfying for the application.
Using:
hFig = gcf;
hAx = gca;
% set the figure to full screen
set(hFig,'units','normalized','outerposition',[0 0 1 1]);
% set the axes to full screen
set(hAx,'Unit','normalized','Position',[0 0 1 1]);
% hide the toolbar
set(hFig,'menubar','none')
% to hide the title
set(hFig,'NumberTitle','off');
frame = %generate image here%
p1 = imshow(frame, [], 'Parent', hAx, 'border', 'tight');
for loop...
frame = %generate image here%
tic;
set(p1, 'CData', frame);
toc;
end
I am now closer to .005
Big thanks for an order of magnitude improvement ( Walter Roberson and Geoff Hayes in https://www.mathworks.com/matlabcentral/answers/180694-fullscreen-of-a-figure-with-no-borders-and-toolbar )
Shane
on 1 Mar 2013
Edited: Shane
on 1 Mar 2013
4 Comments
Image Analyst
on 1 Mar 2013
Shane, this should have been a comment to Walter's Answer, not an answer in itself. Directly writing to cdata will be the fastest way but like you found out, it does not scale the intensity for each image individually. You would have to do that in advance and use the same intensity scale all the time. If you do want to adjust it for each image, then you're back to using a function that does that like imagesc and imshow and unfortunately you're slower again. I guess you could do it yourself by examining the range of each image and adjust the range to be wider only when you needed to expand the range, but that would probably be slow also since the functions do that internally, though you could save time by only widening the scale, which would happen for fewer and fewer images as you go along, and not narrowing it or widening it for each image.
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