A Computational Introduction to Digital Image Processing, 2nd Edition

Image Topology 329

Returning again to Figure 11.20(b), since C(p) = 1 the central pixel p is 8-simple and so

can be deleted without affecting the 8-connectivity of the object. But since A(p) = 1, the

central pixel p is not 4-simple and so cannot be deleted without affecting the 4-connectivity

of the object. This is exemplified in Figure 11.3.

Note that A(p) and B(p) can be computed simply by using the various labeling functions

discussed earlier. For example, consider the neighborhood shown in Figure 11.20(b):

MATLAB/Octave

>> n = [1 1 0;1 1 1;0 0 1]

>> n(5) = 0;

>> max(max(bwlabel(n,4)))

ans =

2

>> max(max(bwlabel(n,8)))

ans =

1

Similarly:

Python

In : from skimage.measure ...