Page 187 - Intelligent Communication Systems
P. 187
158 INTELLIGENT COMMUNICATION SYSTEMS
12.3.3.1 Line Detection
Using the following filter, a line is detected.
12.3,3.2 Determining Contour and Direction
Contour and direction of an image are determined using a Sobel operator, Sobel
operators are given by A* n and Ay,,. The parameter n shows the domain of the fil-
tering operation. At n = 1, the filtering operation is performed for a 3 x 3 domain.
At n = 2, an operation is performed for a 5 x 5 domain. At n = n, the filtering oper-
ation is performed for a (2« + 1) x (2n +1) domain. For example, Sobel operators
A*! and Ay, are given in Eqs. (13) and (14), respectively:
When an input image signal g(i, ) (0 < i, j < N - 1) is given, output signals
j
AX {(i, j) and AF^i, j) are calculated by using filtering operators AJC, and Ay h
respectively, where N is input image size. AJC,(Z, j) and Ay }(i,j) are given in
Eqs, (15) and (16), respectively:
where l<i,j<N-2.
