Figure 15 Cases that do and do not require a special closing routine

Cases where you cannot dilate the center pixel

200  0  200  200  0  0    0  200    0
200  0  200    0  0  0  200    0    0
200  0  200  200  0  0    0    0  200

  1  0    2    1  0  0    0    1    0
  1  0    2    0  0  0    1    0    0
  1  0    2    1  0  0    0    0    2

Cases where you can dilate the center pixel

200  200  200    0  200  0    0  200  200
200    0    0  200    0  0  200    0  200
200  200  200    0    0  0    0    0  200

  1    1    1    0    1  0    0    1    1
  1    0    0    1    0  0    1    0    1
  1    1    1    0    0  0    0    0    1