How to make and save image for each iteration in a for loop?
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Dear all,
I want to know how to make and save an image for each time iteration in a for loop. The following is a simple test code I made, but if I can figure this out I believe mine should be easy to figure out too.
function hel = gr(st)
t = [1:10] ;
for n=1:10
graze(n,1) = (n+1)*st ;
graze(n,2) = (n+1)*(st+1) ;
end
figure(n)
hel = plot(t,graze(:,1),'r+',t,graze(:,2),'b+') ;
legend('ubc','my mood')
xlabel('time')
ylabel('hungry')
% filename = sprintf('mat_img_%d.jpg', n);
% saveas(gcf, filename, 'jpg')
end
every iteration, I'd like to create an image corresponding to the iteration step and save it on my computer. How should I modify this code? Thank you.
6 Comments
Cedric
on 23 Apr 2013
Yes, my example was about the image (if you right click on it, you can see that it is an image). So your question is how to produce this kind of image from a variable's content (?)
Accepted Answer
Cedric
on 23 Apr 2013
Edited: Cedric
on 23 Apr 2013
I understand now; you'll want something like:
filename = sprintf('mat_img_%d.jpg', n) ;
imwrite(B, filename, 'png') ;
Note that you can resize the image if it is too small, e.g.
filename = sprintf('mat_img_%d.jpg', n) ;
B = imresize(B, 100, 'nearest') ; % 100 is the scale factor.
imwrite(B, filename, 'png') ;
Then you can use the code point at by Image Analyst for building the movie.
3 Comments
Cedric
on 23 Apr 2013
Edited: Cedric
on 23 Apr 2013
Actually, you could avoid the double loop and replace it with:
img = ones(size(almos)) ;
img(almos==french) = 0 ;
Then you can proceed as follows:
filename = sprintf('mat_img_%d.jpg', n) ;
img = imresize(img, 400, 'nearest') ;
imwrite(img, filename, 'png') ;
The mistake that you made is that you ask IMSHOW to magnify what it displays, but this function doesn't return the magnified image (it only displays it magnified). The number that is returned is a handle to the image object actually. This is why I proposed IMRESIZE, which outputs a magnified image.
More Answers (1)
Image Analyst
on 23 Apr 2013
3 Comments
Image Analyst
on 23 Apr 2013
If you want images, then use im2frame(). If you want the whole figure including axes, titles, tick marks, etc. then save each figure out with export_fig() to an image file, such as a PNG file, then build the movie by reading in all the frames with imread(), convert to a movie frame with im2frame. See the end of my demo here http://www.mathworks.com/matlabcentral/answers/48797#answer_59652 for an example using the standard demo movie rhinos that ships with MATLAB.
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