save images inside a for loop at uneven intervals

Hi,

I am trying to save images inside the Img array that is generated inside the for loop at uneven iteration numbers. For example sometimes image generated at 10th iteration, while sometimes it's at 150th iteration. How to handle this?

for i = 1:a
    B = some process % my image
    Img(:,:,) = B
    
end

Answer 1

[Voss]

Here's one way that may work for your particular task:

Img = zeros(0,0,0);

for i = 1:a
    
    B = some process % my image
    
    if ... % if some condition says to store this B in Img
        Img(:,:,end+1) = B;
    end
    
end

[Turbulence Analysis]

Thanks!

[Turbulence Analysis]

How to identify the condition to store the image?

if ... % if some condition says to store this B in Img

Img(:,:,end+1) = B;

end

[Voss]

That's up to you. How should it work? For example, is it the case that "some process" generates an image only on random iterations, but every time "some process" generates an image you want to store it?

[Turbulence Analysis]

In the attached file, ts is the time stamps in microseconds. x, y is the image cordinates (1280 x 720) and p represents the intensity.

For each image, I need to accumulate the events corresponds to 200 micro seconds i.e. for first image ts 68942 - 69142 and next 200 micro seconds i.e. 69143 - 69342 for second image and so on...

[Voss]

Maybe something along these lines:

Img = zeros(0,0,0);
last_stored_time = ts(1);

for i = 1:a
    
    B = some process % my image
    
    if ts(i) - last_stored_time >= 200
        Img(:,:,end+1) = B;
        last_stored_time = ts(i);
    end
    
end

[Turbulence Analysis]

Thanks very much!

Answer 2

[Matt J]

One way,

Img=nan(M,N,a);

Isubset=[10 47, 150,...,a]

for i = 1:a
    
    B = some process % my image

    if ismember(i,Isubset)
     Img(:,:,i) = B;
    end
    
end

[Turbulence Analysis]

Hi Matt,

Actually iteration number 10, 150 is just an example, in reality these numbers are highly random.

Answer 3

[Matt J]

If you don't know in advance which and how many loop iterations you'll be storing, it would be best to accumulate them in a cell array, and then post-concatenate:

Img = cell(1,a);

for i = 1:a
    
    B = some process % my image
    
    if ... % if some condition says to store this B in Img
        Img{i} = B;
    end
    
end

Img=cat(3,Img{:}); %empty cells are discarded