Base-object location problems for base-monotone regions

Jinhee Chun, Takashi Horiyama, Takehiro Ito, Natsuda Kaothanthong, Hirotaka Ono, Yota Otachi, Takeshi Tokuyama, Ryuhei Uehara, Takeaki Uno

Research output: Contribution to journalArticlepeer-review

Abstract

A base-monotone region with a base is a subset of the cells in a pixel grid such that if a cell is contained in the region then so are the ones on a shortest path from the cell to the base. The problem of decomposing a pixel grid into disjoint base-monotone regions was first studied in the context of image segmentation. It is known that for a given pixel grid and base-lines, one can compute in polynomial time a maximum-weight region that can be decomposed into disjoint base-monotone regions with respect to the given base-lines (Chun et al., 2012 [4]). We continue this line of research and show the NP-hardness of the problem of optimally locating k base-lines in a given n×n pixel grid. We then present an O(n3)-time 2-approximation algorithm for this problem. We also study two related problems, the k base-segment problem and the quad-decomposition problem, and present some complexity results for them.

Original languageEnglish
Pages (from-to)71-84
Number of pages14
JournalTheoretical Computer Science
Volume555
Issue numberC
DOIs
Publication statusPublished - 2014 Jan 1

Keywords

  • Base-monotone region
  • Computational complexity
  • Image segmentation
  • Room-Edge Problem

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Computer Science(all)

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