Average images as they are captured

I'm writing an AppDesigner GUI that averages n images as they are captured from FLIR camera and saves only the averaged image to a .tif file, then restarts averaging process (ie. loops averaging/saving process for every n captures). Image capture is triggered by button press. Captured images initially saved as value arrays.

Available online examples refer to averaging images that are already saved to computer files (I cannot do this as it uses too much memory).

Relevant code:

% Set up video input object 
    if exist('app.vid','var')
        delete(app.vid)
        clear app.vid
    end 
    
    app.vid=videoinput("mwspinnakerimaq");

% Button pushed function: CaptureaverageimageButton
function CaptureaverageimageButtonPushed(app, event)
    
    % Averaging n images 
    n = str2double(app.AveragenimagesnEditField.Value); %value entered in Edit Field 
    for k=1:n %How does code know image number? Add (k) somewhere?
        im1=getsnapshot(app.vid); 
        [row1,column1]=size(im1);
        if k==1
            sumIm=double(im1); %save first image & its dimensions
            r=row1;
            c=column1;
        else % any image following the first one
		    if r ~= row1 || c ~= column1
			    % Resize to match first image's size
                im1 = reshape(im1,[r,c]); % imresize, reshape, or a different function?
            end 
            sumIm = sumIm + double(im1);
            avgIm=sumIm/n;
            imshow(avgIm,[],'Parent',app.UIAxes2);
            drawnow;
        end 
    end 
    %How to restart loop once averaged image is acquired?
end 

%Save to file: 
    a = 1; %a=averaging loop number (ie. how many loops completed, with n averaged images per loop) 
    while isfile(strcat(app.parentFolder,strcat(app.fullDate,'-',num2str(n),'-',num2str(a),'.tif')))==1
        a= a+1;
    end
    fullFileName=strcat(app.parentFolder,strcat(app.fullDate,'-',num2str(n),'-',num2str(a),'.tif'));
    imwrite(avgIm,fullFileName,"tif")

At the moment, individual images are saved to files, not averages. I think my problem is giving each captured image a "k" value.

Thanks for your help.

Answer 1

[Walter Roberson]

read first image. This establishes size of images. set imgtot to double(img) and count to 1

loop reading images. At each point add double(img) to imgtot and increase count.

At any point that you need an average, divide imgtot by count. You might need to cast() to the class of img before writing.

Though if you im2double each image as it comes in then you will not need to cast the average, if you are happy with imwrite automatically converting to 8 bit when it writes.