1. Introduction
Detecting people in images is a problem with a long history [37], [13], [35], [27], [16], [41], [23], [5]; in the past two years there has been a surge of interest in pedestrian detection [6], [9], [11], [18], [20], [21], [25], [30], [32], [33], [36], [38], [42]. Accurate pedestrian detection would have immediate and far reaching impact to applications such as surveillance, robotics, assistive technology for the visually impaired, content based indexing (e.g. Flickr, Google, movies), advanced human machine interfaces and automotive safety, among others. Automotive applications [12], [14], [34] are particularly compelling as they have the potential to save numerous lives [39].