How to register and average images together from a mat file

I was given a mat file that contains a collection of shifted frames. I need to figure out how to register the shifted frames and average them together. I am pretty unfamiliar with this side of matlab so I don't really know where to begin, any help would be appreciated.

I have attached the mat file and the jpeg.

Answer 1

[Kevin Holly]

Here is some informaiton on image registration:

https://www.mathworks.com/discovery/image-registration.html

https://www.mathworks.com/videos/image-registration-app-1487886446473.html

[Cameron Kreevich]

I have looked through the first article and just watched that video and I understand them however the issues is I am dealing with a mat file that contains a lot of shifted frames of the jpeg. So I need to know how to register the frames from a mat file. Whenever i try to use the imread or imshow with a matfile I get an error. I attached the code I have now but that is as far as I have gotten and as you can see my code does not even bring up the entire jpeg.

[Kevin Holly]

I was able to download and load the mat file just fine. Are you accessing the file remotely? If so, only Version 7.3 MAT-files can be accessed remotely.

load('https://www.mathworks.com/matlabcentral/answers/uploaded_files/817504/undergraduate_data.mat')

Error using load
Unable to read file 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/817504/undergraduate_data.mat'. If it is a Version 7 or earlier MAT-file, consider saving your data afresh in Version 7.3 MAT-files to access it from a remote location.

figure
for index = 1:1:size(photoshift, 3)
imagesc(photoshift(:, :, index)); grid on; daspect( [1 1 1] );drawnow
pause(.5)
end

[Cameron Kreevich]

That is working I was expecting it to be shifted frames of the flock.jpg file in the mat data but I suppose it may not be. The code I had produced 20 shifted frames and I assume there is more based on the dimensions of the mat file but I am not sure how that works. UPDATE, I have confirmed that the 20 frames is all the mat file consists of so if you could point me in the right direction of how to average these frames together that would be amazing.

[Image Analyst]

If all 20 images are in the mat file, then do you consider the first one to be "fixed" and all the rest to be "moving" and need to be aligned with the first?

[Kevin Holly]

clc
clear
close all

load( 'undergraduate_data.mat' ); % 125-by-125-by-30

[optimizer, metric] = imregconfig('monomodal');

% Assuming first image is fixed
 
new = photoshift;
figure
for index = 2:1:size(photoshift, 3)
subplot(2,1,1)
imagesc(photoshift(:, :, index)); grid on; daspect( [1 1 1] );drawnow
new(:,:,index) = imregister(photoshift(:, :, index),photoshift(:, :,1),"affine",optimizer, metric);
subplot(2,1,2)
imagesc(new(:, :, index)); grid on; daspect( [1 1 1] );drawnow
pause(1)
end

average_new = mean(new,3);

[Cameron Kreevich]

Yes i am assuming the 1st frame is fixed, with the above code the first figure displayed is the 20 framees and the one underneath is the frames averaged together correct?

[yanqi liu]

yes，sir，may be use moving matrix，such as

clc
clear
close all

load( 'undergraduate_data.mat' ); % 125-by-125-by-30

[optimizer, metric] = imregconfig('monomodal');

% Assuming first image is fixed

new = photoshift;
figure
for index = 2:1:size(photoshift, 3)
    subplot(2,1,1)
    imagesc(photoshift(:, :, index)); grid on; daspect( [1 1 1] );drawnow
    % use now photoshift and last new
    new(:,:,index) = imregister(photoshift(:, :, index),new(:,:,index-1),"affine",optimizer, metric);
    subplot(2,1,2)
    imagesc(new(:, :, index)); grid on; daspect( [1 1 1] );drawnow
    pause(0.1)
end

average_new = mean(new,3);
figure; imshow(average_new,[]);