fn = '101208 L AGUA RL P1500 a.jpg'
fns1 = '101208 L AGUA RL P1500 a T1.jpg'
fns2 = '101208 L AGUA RL P1500 a T2.jpg'
th = 0.01

i1 = imread(fn);
se = strel('disk',10);
i2 = imtophat(i1,se);
i3 = im2bw(i2,th);

figure(1)
imshow(i2)
figure(2)
imshow(i3)
imwrite(i2,fns1)