(7) Perimeter
Def.1: The total length of lines that separate pixels
of S from S .
Def.2: The number of boundary pixels.
(8) Compactness
P2
c
A
Where P— perimeter, A— area. The smallest value of
Horizontal projection:
H[i]B[i, j]
j
Vertical projection:
V[j]B[i, j]
j
For a well alined text binary image, the projection has comb shape, image can be easily partitioned.
b. 8-neighbors: the 4-neighbors pixels plus the diagonal neighbors.
[i-1,j]
[i-1,j-1] [i-1,j] [i-1,j+1]
[i,j-1] [i,j] [i,j+1]
[i,j-1]
[i,j]
[i,j+1]
[i+1,j]
[i+1,j-1] [i-1,j] [i+1,j+1]
(3) Boundary-following:
Track boundary pixels of a region in a particular order (chain sequence)
Algorithm:
a) Use systematic scan (from left to right, and from top
