First you need to make this greyscale image fully black white. This can be done with a simple threshold with
threshold = 0.5; % fiddle with this
BW = im2bw(yourImage, threshold);
BW = ~BW; % the following code needs white spots black background
stats = regionprops('table',bw,'Centroid','MajorAxisLength','MinorAxisLength')
test if everything was found with
imshow(yourImage)
centers = stats.Centroid;
diameters = mean([stats.MajorAxisLength stats.MinorAxisLength],2);
radii = diameters/2;
hold on
viscircles(centers,radii);
hold off
Most likely, due to the complexity of your image you will need to look into adaptive thresholding as well as some image processing to clean it up such as imfill. Hope this gets you on your way.
