Tutorial 1 : Connectivity, Connected Filters, and Beyond

Presenters:

Michael H.F. Wilkinson, University of Groningen, Netherlands
Georgios K. Ouzounis, Joint Research Center of the European Commission (JRC)

Abstract

Connected filters have rapidly become one of the most important classes of morphological filters. They allow edge preserving image simplification using a variety of strategies, and can be applied to many different tasks, ranging from image de-noising at the low-level end of the spectrum, to object recognition at the high-level task. Besides their edge preserving nature, connected filters can model the Gestalt notion of perceptual grouping, by using more generalized notions of connectivity, allowing, e.g., a flock of birds to be viewed as a single entity. Furthermore, they allow very fast multi-scale analysis of images and volumes, and can be made scale or even affine invariant very easily. They have deep theoretical links to segmentation, as witnessed by the recent development of the notion of connective segmentation.

In this tutorial the foundations of connected filters and connectivity will be presented. The aim is to give participants insight into the properties of these methods, and how to apply them in practical problem.

This tutorial consists of three lectures. The first is given by Michael Wilkinson, and will cover the most important types of connected filters, multi-scale techniques, and representation schemes. It will deal also with extending the notion of connectivity beyond the usual graph-based forms. Applications including 3D medical imaging and visualization, and astronomy will be used to illustrate the theory. The second lecture is given by Georgios Ouzounis, and will deal with image decomposition schemes based on connected operators, hierarchical image representation and state of the art algorithms for applications related to massive image data handling. The talk will cover the latest developments on graph-based connected operators for image segmentation that utilize pixel adjacency relations beyond what is known as the standard notion of connectivity. All theoretical constructs and operators will be demonstrated on very high resolution satellite and aerial imagery and applications on real scenarios will be given. The third lecture will be given by Michael Wilkinson, and explore notions of hyperconnectivity and attribute-space connectivity, which expand the mathematical framework of these object-oriented filters, especially to dealing with overlapping structures. We will round off the tutorial with some demos, and encourage a discussion amongst participants to explore how connected methods might be used in the context of their research.

Biography of the presenters

Michael Wilkinson obtained an MSc in astronomy from the Kapteyn Laboratory, University of Groningen in 1993, after which he worked on image analysis of intestinal bacteria at the Department of Medical Microbiology, University of Groningen, obtaining a PhD at the Institute of Mathematics and Computing Science, also in Groningen, in 1995. He was appointed as researcher at the Centre for High Performance Computing in Groningen working on simulating the intestinal microbial ecosystem on parallel computers. During that time he edited the book “Digital Image Analysis of Microbes” (John Wiley, UK, 1998) together with Frits Schut. After this he worked as a researcher and lecturer at the Johan Bernoulli Institute for Mathematics and Computer Science (JBI) on image analysis of diatoms. He is currently senior lecturer at the JBI, working on morphological image analysis and especially connected morphology. At ICIP2008, he organized a special session on connected filters together with Philippe Salembier. He organized the 2009 International Symposium on Mathematical Morphology (ISMM) together with Jos Roerdink, is member of the ISMM Steering Committee, and has given several tutorials on connected filters at international conferences.

Georgios K. Ouzounis obtained a BEng. degree in Electrical and Electronic Engineering and an M.Phil. degree in Computer Science from the Department of Computing and Electrical Engineering, Heriot Watt University, Edinburgh, Scotland in 1998 and 2001 respectively. He received his Ph.D. on image analysis and connected morphological filters from the Johann Bernoulli Institute of Mathematics and Computing Science, University of Groningen, The Netherlands, in 2009. From January 2008 to September 2009 he worked at the Democritus University of Thrace - 2nd Department of Surgery, University General Hospital of Alexandroupoli, Greece, as a medical image analyst developing 3-D CT segmentation methods for diagnostic purposes of interest to the Urological Clinic. Currently he is researcher at the Global Security and Crisis Management Unit - Joint Research Center of the European Commission in Ispra, Italy, where he works on the development of advanced VHR satellite image analysis algorithms.