How detect spot white circle on image

I would like detect spot white are like below image . Hope anyone help . Thanks!

[Rena Berman]

(Answers Dev) Restored edit

Answer 1

[KSSV]

I = imread('Screen Shot 2017-06-06 at 3.54.58 PM.png') ;
im = imclearborder(im2bw(I));
im_fill = imfill(im, 'holes');
s = regionprops(im_fill, 'Area', 'PixelList');
[~,ind] = max([s.Area]);
pix = sub2ind(size(im), s(ind).PixelList(:,2), s(ind).PixelList(:,1));
out = zeros(size(im));
out(pix) = im(pix);
%  imshow(out);
[y,x] = find(out) ;
idx = boundary(x,y) ;
% idx = convhull(x,y) ;
imshow(I)
hold on
plot(x(idx),y(idx),'r','linewidth',3)

Code taken from: https://in.mathworks.com/matlabcentral/answers/343337-how-to-remove-small-portion-in-an-image

If boundary doesn't work, use convexhull

[KSSV]

Attach only original image ...

Answer 2

[Image Analyst]

KSSV's code finds the largest blob that is not touching the border, whereas you actually want roundish objects.

Like I said in your duplicate post, You could use my code for circularity. Or you could also look for Solidities close to 1, or get the BoundingBox and look for aspect ratios close to 1.