Some of the objects are connected to the surrounding white blob. You'll need to deal with that. You might be able to do something like:
A = imread('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1004025/image.png');
A = rgb2gray(A)>127; % binarize
B = imopen(A,ones(3)); % try to break connectivity
B = imclearborder(B); % clear border
B = A & ~B; % difference of original and smoothed copy sans border
B = bwareafilt(B,1); % select only the border object, delete speckles
B = A & ~B; % remove border object from original image
imshow(B)
