Title: Rejection Based Classifier for Target Detection in Images

By: Michael Elad*

Affiliation: SCCM program - Stanford University

Abstract:
One of the most fundamental problems in the treatment of high-dimensional data is classification of a cloud of points in R^D into several sub-classes based on training data. An important such task is the pattern detection problem in images, which requires a separation between 'Target' and 'Clutter' classes, where every instance of a pattern in each of these classes appears as a sequence of D pixels. In most cases, the probability of the 'Target' class is substantially smaller compared to that of the 'Clutter'. In this talk we describe a new classifier that exploits this property, yielding a low complexity yet effective target detection algorithm. This algorithm, called the Maximal Rejection Classifier (MRC), is based on successive rejection operations. Each such rejection stage is performed using a linear projection followed by thresholding. The projection direction is designed to maximize the number of rejected 'Clutter' points from further consideration. An application of detecting frontal and vertical faces in images is demonstrated using the MRC with encouraging results.

* Joint work with Yacov Hel-Or, IDC,
Herzlia, Israel and Renato Keshet, Hewlett-Packard Laboratories - Israel.