function testDilate
a = im2double ( imread ('eight.tif') );
b = a < isodata (a);
isodata(a)
%se=zeros(7,7);
%se(1,1)=1;
%c = imdilate(b, se);

N = 15;
c = imdilate(b, strel('square', N));
d = imerode(c, strel('square', N));
%oimshow(a,b,d,c)

subplot(2,2,1), imshow(a);
subplot(2,2,2), imshow(b);
subplot(2,2,3), imshow(c);
subplot(2,2,4), imshow(d);