A pixel's membership in a cluster depends on the neighborhood rule used.
This research employs the North-East-West-South (NEWS) neighborhood rule
in which two pixels are included in the same cluster if both the pixels are in
the same class and the pixels are neighbors according to the
neighborhood rule. NEWS neighbors share a pixel boundary on the north, east,
west, or south. Consider the map as a 2-dimensional matrix of size
and the current pixel is map(i,j) where 
and 
. The north, east, west, and south neighbors would have the
coordinates map(i,j-1), map(i+1,j),
map(i-1,j), and map(i,j+1), respectively (see Figure 5).
Figure 5: North, east, west, south relationship to pixel(i,j).