Topology-preserving hexagonal thinning

Abstract

Thinning is a well-known technique for producing skeleton-like shape features from digital binary objects in a topology-preserving way. Most of the existing thinning algorithms work on input images that are sampled on orthogonal grids; however, it is also possible to perform thinning on hexagonal grids (or triangular lattices). In this paper, we point out to the main similarities and differences between the topological properties of these two types of sampling schemes. We give various characterizations of simple points and present some new sufficient conditions for topology-preserving reductions working on hexagonal grids.

Keywords:

• digital topology
• topology preservation
• thinning
• hexagonal grids

2010 AMS Subject Classifications::

• 68U10
• 68T10
• 52C99
• 68R99

Acknowledgements

This research was supported by the European Union and the European Regional Development Fund under the grant agreements TÁMOP-4.2.1/B-09/1/KONV-2010-0005 and TÁMOP-4.2.2/B-10/1-201-0012, and the grant CNK80370 of the National Office for Research and Technology (NKTH) and the Hungarian Scientific Research Fund (OTKA).