MATLAB: Drawnow() causing very slow display of images

drawnowimshowMATLABslowspeed

Hi all,

I've read several other questions on this but didn't find a satisfactory answer. My apologies however, if this is already up.

I am building a GUI to display processed video. I do this using

imshow(image,'Parent',axes)

then

drawnow

for each frame in a loop. It is VERY slow. Approx 0.5 seconds per frame (~12 seconds to display 1 second of video in real time). It also accounts for half my total processing time per frame.

Can I make it faster?

Any help is greatly appreciated!!

Cheers, KB

Best Answer

I solved that problem with older versions of MATLAB by putting in a "cla" or "cla('reset')" into the code just before the imshow. Evidently with older versions sometimes the images "stack up" and are all in there and you're just piling one on top of another and it gets slower and slower as it runs out of memory. Try that and let me know if it speeds it up.

Related Solutions

MATLAB: How to load video on matlab gui

You can use implay(): https://www.mathworks.com/help/releases/R2020b/images/ref/implay.html to play video.

You can also make your own GUI as shown in following code

v = VideoReader('xylophone.mp4');
figure();
ax = axes();
frame = readFrame(v);
im_frame = imshow(frame, 'Parent', ax);
while hasFrame(v)
    im_frame.CData = readFrame(v);
    drawnow
end

MATLAB: Which is the fastest way to display gray scale images (480 by 640)

You have to get the handle to the image in your axes, and then assign your webcam snapshot to the CData property (I think that's what it's called). This will be faster than imshow.

Best Answer

Related Solutions

MATLAB: How to load video on matlab gui

MATLAB: Which is the fastest way to display gray scale images (480 by 640)

Related Question