MATLAB: Multiple face detection and cropping from multiple images

Question

I want to read multiple images from directory where each image contains multiple faces, I want to detect faces from each image and want to crop the detected faces and want to save these faces into another directory.

I tried the following code, It performs the face dection and cropping process on only one image. I want to perform face detection and cropping process on all of the images present in the image directory.

location = 'E:\fer1\frames\*.jpg';       %  folder in which your images exists
ds = imageDatastore(location)         %  Creates a datastore for all images in your folder
% Loop through the datastore, read and display each image in its own window.
while hasdata(ds) 
    img = read(ds) ;             % read image from datastore
    figure, imshow(img);    % creates a new window for each image
end
%figure(1);
%imshow(img); 
FaceDetect = vision.CascadeObjectDetector; 
FaceDetect.MergeThreshold = 7 ;
BB = step(FaceDetect, img); 
figure(2);
imshow(img); 
for i = 1 : size(BB,1)     
  rectangle('Position', BB(i,:), 'LineWidth', 3, 'LineStyle', '-', 'EdgeColor', 'r'); 
end 
for i = 1 : size(BB, 1) 
  J = imcrop(img, BB(i, :)); 
  figure(3);
  subplot(6, 6, i);
  imshow(J); 
end

Answer 1

imds = imageDatastore ( 'face' , ...
    'IncludeSubfolders' , true, ...
    'LabelSource' , 'foldernames' );
idx = randperm (numel (imds.Files), 4);
j = 1;
figure
for t = 1: 4
    img = readimage (imds, idx (t));
    FaceDetect = vision.CascadeObjectDetector; 
    FaceDetect.MergeThreshold = 7;
    BB = step (FaceDetect, img); 
    figure (2);
    imshow (img); 
    for i = 1: size (BB, 1)     
      rectangle ( 'Position' , BB (i, :), 'LineWidth' , 3, 'LineStyle' , '-' , 'EdgeColor' , 'r' );
    end 
    for i = 1: size (BB, 1)
      J = imcrop (img, BB (i, :)); 
      figure (3);
      subplot (6, 6, i);
      imshow (J); 
      j = j + 1;
      imwrite (J, [j, '.jpg' ])
    end
end