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Chapter 3 ■ Digital Morphology 119

(a) (b) (c) (d) (e)

(f) (g) (h) (i)
Figure 3.21: Filling a region using conditional dilation. (a) The boundary of the region to
be filled. This is the boundary found in Figure 3.19. (b) The structuring element. (c) The
seed pixel, and iteration 0 of the process. (d) After iteration 1. (e) After iteration 2. (f) After
iteration 3. (g) After iteration 4. (h) After iteration 5 the dilation is complete. (i) Union of
(h) with (a) is the result.

A MAX program for region filling requires the input of the coordinates of
the seed pixel, which is the first time that integer input has been performed in
aMAX program. It is:

// Fill a region with 1 pixels - Conditional Dilation
pixel p;
int i,j;
image a, b, c, d;
begin
do a << “$1“;
message “FILL: Enter the coordinates of the seed pixel “;
doi<<““; do j<<““;
p := [i, j]; // SEED pixel.
b := {[3,3], [1,1], “010111010“};
c:=!a+ p;
a:=~a;
loop
d:=(c++b) * a;
exit when d=c;
c:=d;
end;
do c + ~a >> “$2“;
end;

3.3.10 Counting Regions

As a final example of the uses of morphology in binary images, it is possible to
count the number of regions in an image using morphological operators. This