The Robotics Institute

RI | Seminar | October 13, 2006

Robotics Institute Seminar, October 13, 2006
Time and Place | Seminar Abstract | Speaker Biography | Speaker Appointments

Object Classification, Recognition and Segmentation

by a Hierarchy of Abstract Fragments

Shimon Ullman

Ruth and Samy Cohn Professor of Computer Science

Weizmann Institute of Science


Time and Place

Mauldin Auditorium (NSH 1305)
Refreshments 3:15 pm
Talk 3:30 pm



I will describe an approach to object recognition which combines general classification, individual recognition, and figure-ground segmentation. The approach is based on representing shapes within a class by a hierarchy of shared sub-structures called fragments, selected by maximizing the information delivered for classification. For the task of individual recognition, these fragments are generalized to become abstract fragments, representing the same object part under different viewing conditions. The resulting feature hierarchy is used to recognize new images by the application of a feed-forward sweep from low to high levels of the hierarchy, followed by a sweep from the high to low levels. Finally, image segmentation into an object and background is combined in this approach with the recognition process. Some relations to the human visual system will be briefly discussed.


Speaker Biography


Shimon Ullman is the Ruth and Samy Cohn Professor of Computer Science in the department of computer science and applied mathematics at the Weizmann Institute of Science in Israel. He received his Bs.C. from the Hebrew University in Jerusalem, and Ph.D. from M.I.T, where he has been a Professor in the Brain and Cognitive Science Department and in the Artificial Intelligence Laboratory. His main areas of research are human and computer vision, cognition, and brain modeling.


Speaker Appointments

For appointments, please contact Janice Brochetti (

The Robotics Institute is part of the School of Computer Science, Carnegie Mellon University.