The Construction of Bounded Irregular Pyramids with a Union-Find Decimation Process

Abstract

The Bounded Irregular Pyramid (BIP) is a mixture of regular and irregular pyramids whose goal is to combine their advantages. Thus, its data structure combines a regular decimation process with a union-find strategy to build the successive levels of the structure. The irregular part of the BIP allows to solve the main problems of regular structures: their inability to preserve connectivity or to represent elongated objects. On the other hand, the BIP is computationally efficient because its height is constrained by its regular part. In this paper the features of the Bounded Irregular Pyramid are discussed, presenting a comparison with the main pyramids present in the literature when applied to a colour segmentation task.

Visual Attention Mechanism for a Social Robot

“…In order to deal with these scenes, a tracking approach for 'inhibition of return' is employed [32]. The 'proto-objects' selection and the tracking process will be conducted using the same hierarchical structure: the Bounded Irregular Pyramid (BIP) [28,31]. Figure 1 shows an overview of the proposed attention mechanism.…”

“…The final set of regions constitute the set of 'proto-objects'. Both stages are performed using the Bounded Irregular Pyramid (BIP), an irregular pyramid which has demonstrated to be able to perform fast segmentation of color images [31].…”

Affine image region detection and description

“…• Irregular node generation process: any regular or irregular node of level l which is not linked to a node at l+1 is included in a union-find grouping process [15], [14]. This union-find process only generates irregular nodes at level l+1.…”

“…Three empirical measures have been employed: the ShiftVariance (SV) and the F and Q functions [14]. Shift variance means that the image segmentation produced by pyramidbased algorithms varies when the base of the pyramid is shifted slightly.…”

“…This measure penalizes more rigidly the existence of small regions. For comparison purposes, five irregular pyramids are employed: the BIP [14], the localized pyramid (LP) [7], the segmentation approach proposed by Lallich et al [10] (MP), the hierarchy of image partitions (HP) [6], and the combinatorial pyramid (CoP) [2]. Four features have been evaluated: the F and Q functions, the SV measure, and the execution time.…”