Image Processing Reference
In-Depth Information
Offshoot
FIGURE 1.23: A non-simple contour with an offshoot.
2. How do you define the adjacency relationship in a hexagonal grid? How
many types of adjacency relationships could be there? Discuss the advan-
tage and disadvantage of using hexagonal grids for image representation
with respect to the conventional rectangular grid.
3. Suppose there are offshoots in a contour that make it non-simple. A
typical example is shown in Fig. 1.23. In the absence of those offshoots,
the contour becomes simple. Discuss an image processing operation to
make it a simple contour.
4. Write the safe point deletion conditions for right, top, and bottom edge
points in 2-D following the same notations given in Section 1.4.1.
5. Identify the digital neighborhood planes, where simple point check for
a front edge point in 3-D is to be carried out in the algorithm ESPTA
(refer to Section 1.4.1.1).
6. What is the Euler number of a hollow cylinder that contains another
hollow cylinder inside? Discuss why in 2-D a skeleton preserves both the
adjacency tree and Euler number of the original pattern.
7. Modify the ESPTA to apply in a (18,6) grid.
8. Find the unit normal vectors of digital neighborhood planes as discussed
in Section 1.3.3.3.
9. Prove both the lemmas related to NPS given in the Section 1.3.3.3.
10. Using the same notations of a set of points in the 3×3×3 neighborhood
of a point in a 3-D digital grid (refer to Fig. 1.16), enumerate the set of
points for each DNP as shown in Fig. 1.11.
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