Morphological Transformation, remove border border of a closed image

Using morphological operations and connected components algorithm, the problem can be solved with the minor loss of bottom pixels.For example:

a=imread('imag.jpeg');
figure;imshow(a)
se = strel('line',8,90);
eroded = imerode(a,se);
b=logical(eroded);
st=regionprops('Table',b(:,:,1),'Area');
m=maxk(st.Area,2);
biggest = bwareafilt(b(:,:,1),[m(2) m(1)]);
figure;imshow(biggest)
dil=imdilate(biggest,se);
figure;imshow(dil)

The above code results in the below image. You can try with some other parameters of morphological processing and check if it will be more clear.