Excluding types of extension files on a loop

I am doing my academic research, it is based on medical image processing. My code will go into a folder path and handle all ".jpg" images, however inside the folder I have some files that I wouldn't want to read and I can't remove from there, as my database is too large, I need skip these files through code to not do manually.

clc;
close all;
mainpath = 'path';
original= dir(mainpath);
quantity = length(original);
x = zeros(14,4,quantity);
figures = 1;
for i=1:quantity
    imagename=original(i).name; 
    w(i)={imagename};
    [path, filename, ext]=fileparts(imagename);
    if (ext == extensao)
             img = imread([mainpath,'',imagename]); 
                 [l, c, canais] = size(img);
            % if (canais==3)
            %     img = rgb2gray(img);
            % end
             maximo = max(max(img));
             minimo = min(min(img));
             [glcms,SI] = graycomatrix(img,'NumLevels',maximo-minimo,'Offset' ,[0 1],'GrayLimits', [minimo maximo], 'Symmetric', true);
             soma = sum(sum(glcms));
             glcms = glcms/soma;
             x(:,1,figures) = haralickTextureFeatures(glcms);
             i = 2;
          for angulo = 1:-1:-1
                 [glcms,SI] = graycomatrix(img,'NumLevels',maximo-minimo,'Offset' ,[-1 angulo],'GrayLimits', [minimo maximo], 'Symmetric', true);
                 soma = sum(sum(glcms));
                 glcms = glcms/soma;
                 x(:,i,figures) = haralickTextureFeatures(glcms);
                 i = i+1;
          end

             figures = figures+1;
   else 
       figures = figures+1;
   end

end

filename = 'Resultado Test.xlsx';
matrizFinal = zeros(4,quantity);
for j = 1:14
    k=1;
    for i=1:quantity;
        matrizFinal(:,i) = x(j,:,i)
        name(i)=w(k)
        k=k+1
    end

    xlswrite(filename,nome,j,'A1');
    xlswrite(filename, matrizFinal,j,'A2');
  end

Unrecognized function or variable 'quantidade'.

Answer 1

[Walter Roberson]

original = dir( fullfile(mainpath, '*.jpg'));

now it will only find jpg files

[Flávio Nóbrega]

Thank you, it worked right away, so simple, i remember that in the beginning of writing code i tried this but i was getting the same error message and i removed.

:)

Answer 2

[Akira Agata]

You can do that more effective way by using wild card character "*", like:

imgFolder = pwd; % <- set to your image folder path
imgList = dir(fullfile(imgFolder,'*.jpg'));

for kk = 1:numel(imgList)
  filePath = fullfile(imgList(kk).folder, imgList(kk).name);
  I = imread(filePath);
  
  % [Do something to each image]
  
end

[Flávio Nóbrega]

Thank you, it worked !! :)

Answer 3

[Image Analyst]

It's best to do what the others showed you and just get a list that has only JPG files in it in the first place. However just for completeness, I'm going to show you how to skip them in the loop

for i=1:quantity
    imagename=original(i).name; 
    if contains(imagename, '.jpg', 'IgnoreCase', true)
        continue; % Skip this one.
    end

Now, next is the issue of using JPG images in the first place. DON"T DO IT! If you can at all help it, never use JPG images for image analysis because it is a lossy compression format and you won't necessarily recall the same pixel values that the image had before it was saved to disk. Use PNG (lossless compression) or TIF or BMP.

[Flávio Nóbrega]

I see, thank you for that, it was very helpful. As for the image type, my database only contains .jpg images, if you have any recommendations for a .png database of lung disease patients it would help.

:)

[Image Analyst]

Strange. I thought usually medical images were dicom. Are you sure these are genuine, original medical images?