I am trying to use background subtraction on a set of images in a folder

I am new to the image processing side of MATLAB. The images I am trying to subtract the background from are a set of frames from a video. I have successfully subtracted the background from one using a different photo I constructed in the paint app (the area of interest is highlighted in white, leaving just that area after the subtraction (this is quite important). Since the camera is stationary, I need to use the same singular photo to carry out background subtraction on all 95 frames. I managed to somewhat do this using the code below, however the images were put into a cell, therefore I could not save the images, see them individually, or watch them as a video. Is this possible to do automatically, subtracting the background from 95 different images using the same one image to subtract from, since repeating this process in paint 95 times would take a long time? Or is there a way to remove the images from the cell where I can save them, see them individually and watch them together as a video? Thanks

[Andrew Palmer]

Sorry, the code that gave me the subtracted images in a cell is below since I forgot to attach.

filePattern=fullfile('C:\', 'folder1', 'folder2','*.jpg');

images1=dir(filePattern);

image2=imread('subtract.jpg');

for k = 1:95

baseFileName=images1(k).name;

fullFileName=fullfile(images1(k).folder, baseFileName);

fprintf(1, 'now reading %s/n', fullFileName);

end

imageArray=imread(fullFileName);

imshow(imageArray)

for k = 2:95

subtracted{k-1}=image2-imageArray;

end

Answer 1

[Image Analyst]

Try this:

folder = fullfile('C:\folder1\folder2');
filePattern = fullfile(folder, '*.jpg');
fileList = dir(filePattern);
numberOfFiles = numel(fileList);
subtractionFileName = 'subtract.jpg'; % or fullfile(folder, 'subtract.jpg') if it's in the same folder.
if ~isfile(subtractionFileName)
    errorMessage = sprintf('Subtraction image not found:\n%s', subtractionFileName);
    uiwait(errordlg(errorMessage));
    return;
end
backgroundImage = imread(subtractionFileName);
for k = 1:numberOfFiles
    baseFileName = fileList(k).name;
    if contains(baseFileName, 'subtract', 'IgnoreCase',true)
        continue;
    end
    fullFileName = fullfile(fileList(k).folder, baseFileName);
    fprintf(1, 'Now reading %s/n', fullFileName);
    thisImage = imread(fullFileName);
    % Do the subtraction.  Use subtractionImage{k} if you need to save them all for some reason
    % and you have enough memory to save them all.
    subtractionImage = thisImage - backgroundImage;
    % Display the image.
    imshow(subtractionImage, []);
    caption = sprintf('Image #%d of %d : %s', k, numberOfFiles, baseFileName);
    title(caption, 'Interpreter','none');
    drawnow; % force it to update the screen immediately.
end
uiwait(helpdlg('Done!'));

[Andrew Palmer]

Thank you very much for your help that's worked exactly how I need it

[Andrew Palmer]

Hi. Turns out I do need to save them all individually, since I need to then go on to use imfindcircles to identify pillars in the sequence of images. I put in the suggested code above, using subtractionImage{k} instead, and tried to use imwrite() to save them to a folder, however the error message said since they were in a cell they could not. Firstly, is there a different way to save them individually, despite the fact they're in a cell? Or is there another way to save them not in a cell? Or is there a way to put the cell direclty into another code in order to apply imfindicircles to the sequence. Thanks again

[Image Analyst]

You can save the images one at a time with imwrite() or else you can save the whole cell array into a .mat file with save() and then recall it with load().