Yeah, I tried skimage.morphology.disk(2). Any visible change is not seen. The kernel i used is from opencv, using cv2.getStructuringElement(cv2.MORPH_ELLIPSE,(5,5)). It is elliptical actually. disk(2) gives more like a diamond.

In [21]: cv2.getStructuringElement(cv2.MORPH_ELLIPSE,(5,5))
Out[21]: 
array([[0, 0, 1, 0, 0],
       [1, 1, 1, 1, 1],
       [1, 1, 1, 1, 1],
       [1, 1, 1, 1, 1],
       [0, 0, 1, 0, 0]], dtype=uint8)

In [20]: m.disk(2)
Out[20]: 
array([[0, 0, 1, 0, 0],
       [0, 1, 1, 1, 0],
       [1, 1, 1, 1, 1],
       [0, 1, 1, 1, 0],
       [0, 0, 1, 0, 0]], dtype=uint8)

Should I change it to skimage.morphology.disc ?