Thesis (PDF) - Signal & Image Processing Lab
Thesis (PDF) - Signal & Image Processing Lab
Thesis (PDF) - Signal & Image Processing Lab
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5.1. THE COMPLETE INF-SEMILATTICE OF TREE REPRESENTATIONS 63<br />
5.1 The Complete Inf-Semilattice of Tree Repre-<br />
sentations<br />
Let L be an arbitrary set of “labels”, and let t = (V, E) be a rooted tree, with root<br />
r, such that V ⊆ L. Therefore t is a tree of labels. Moreover, let M : E ↦→ V be an<br />
image of vertices, mapping each point in E to a vertex of t. As before, E is either an<br />
Euclidean space or a discrete rectangular grid within the image area.<br />
Definition 10. (Tree Representation) The structure T = (t, M) shall be called a<br />
tree representation. The set of all tree representations associated to the label set L<br />
and to the root r shall be denoted by T L<br />
r .<br />
Figure 5.2 depicts an example of a tree representation.<br />
Consider the following relation between tree representations: For all T1 = (t1, M1)<br />
and T2 = (t2, M2) in T L<br />
r ,<br />
T1 ≤ T2 ⇐⇒ t1 ⊆ t2 and M1 �t2 M2, (5.1)<br />
where ⊆ is the usual graph inclusion, and �t2 is the partial ordering of vertices (see<br />
Figure 5.2: An example of image tree representation. An image with V1, V2, V3 and<br />
V4 zones is represented as a tree. Each pixel in this zone is mapped to a corresponding<br />
label.