morphology operations top hat and bottom hat

 I = im2single(imread('rice.png'));
 htop = vision.MorphologicalTopHat('Neighborhood',strel('disk', 12));

% Improve contrast of output image
   hc = vision.ContrastAdjuster;  J = step(htop,I);
  J = step(hc,J);
  figure;

 subplot(1,2,1),imshow(I); title('Original image');
 subplot(1,2,2),imshow(J);
 title('Top-hat filtered image');




I = im2single(b);
 hbot = vision.MorphologicalBottomHat('Neighborhood',strel('disk', 5));
 J = step(hbot,I);
 figure;
 subplot(1,2,1),imshow(I); title('Original image');
 subplot(1,2,2),imshow(J);
 title('Bottom-hat filtered image');