The Weizmann Institute of Science Faculty of Mathematics and Computer Science Vision and Robotics Seminar Barak Fishbain University of California at Berkeley will speak on Network Flow Algorithms for Segmentation of Multi-dimensional Data Lecture Hall, Room 1, Ziskind Building on Thursday, March 4, 2010 12:00 - 13:00 Abstract: In partitioning, clustering and grouping problems a typical goal is to group together similar objects, or pixels in the case of image processing. At the same time another goal is to have each group distinctly dissimilar from the rest and possibly to have the group size fairly large. These goals are often combined as a ratio optimization problem. State-of-theart methods address these ratio problems by employing nonlinear continuous approaches, such as spectral techniques. Such techniques deliver solutions in real numbers which are not feasible to the discrete partitioning problem. Furthermore, these continuous approaches are relatively computationally expensive. In this talk a novel graph-cut based approaches for optimally solving a set of ratio problems are presented. These algorithms guarantee optimal solution to the respective problem and consistent output between different runs. These methods are highly robust and most efficient which allows for the segmentation of significantly large data sets. Segmentation of Video sequences and 3D Magnetic Resonance Imagery (MRI) are presented as representative examples. The algorithms presented here use as a subroutine a minimum s, t-cut procedure on a related graph which is of polynomial size. The s, t-cut problem is optimally solved by using the efficient Hochbaum's PseudoFlow (HPF) algorithm. In this talk a recent computational study comparing different leading solvers for this problem is presented. The study shows that the HPF is the most stable (with respect to problem's size) and efficient (in terms of running times and memory utilization) algorithm for this task. The work was done with Prof. Dorit S. Hochbaum, University of California at Berkeley. [Barak Fishbain received his Ph.D in EE from Tel-Aviv University, Israel in 2008. His research interests are Computer Vision, Image Processing, Video Surveillance and Medical Imaging. Currently he is a postdoctoral fellow in the Dept. of Industrial Engineering and Operations Research in the University of California at Berkeley, USA] --------------------------------------------------------- Technion Math Net-2 (TECHMATH2) Editor: Gershon Wolansky Announcement from: Diana Mandelik