From: Automatic detection of abnormalities in mammograms
P(x−1,y−1)
P(x−1,y)
P(x−1,y+1)
P(x,y−1)
P(x,y)
P(x,y+1)
P(x+1,y−1)
P(x+1,y)
P(x+1,y+1)