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TITLE: Finding Shareable Informative Patterns and Optimal Coding Matrix for Multiclass Boosting
PRESENTER: Bang ZHANG, http://www.cse.unsw.edu.au/db/staff/staff_details.php?ID=zhangb, bzha328@cse.unsw.edu.au
AFFILIATION:School of Computer Science and Engineering, UNSW; NICTA, http://www.cse.unsw.edu.au
DATE: Tuesday 28th July 2009
TIME: 11:00:00
PLACE: CSE Seminar Room, Level 1, K17
ABSTRACT:
A multiclass classification problem can be reduced to a collection of
binary problems using an error-correcting coding matrix that specifies the
binary partitions of the classes. The final classifier is an ensemble of
base classifiers learned on binary problems and its performance is
affected by two major factors: the qualities of the base classifiers and
the coding matrix. Previous studies either focus on one of these factors
or consider two factors separately. In this paper, we propose a new
multiclass boosting algorithm called AdaBoost.SIP that considers both two
factors simultaneously. In this algorithm, informative patterns, which are
shareable by different classes rather than only discriminative on specific
single class, are generated at first. Then the binary partition preferred
by each pattern is found by performing stage-wise functional gradient
descent on a margin-based cost function. Finally, base classifiers and
coding matrix are optimized simultaneously by maximizing the negative
gradient of such cost function. The proposed algorithm is applied to scene
and event recognition and experimental results show its effectiveness in
multiclass classification. This work will be presented at ICCV this year.
BIOGRAPHY OF SPEAKER:
Bang Zhang received the BS and MS degrees in computer science from Sun
Yat-Sen University and University of New South Wales, respectively. He is
currently a PhD student in the School of Computer Science and Engineering at
University of New South Wales and National ICT Australia. Bang is a student
member of IEEE. His research interests include computer vision, pattern
recognition, and machine learning. Bang has published about ten papers in
the areas of computer vision.
Host:
Yang Wang
Seminar Convenor:
Van Hai Ho
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