This is a neural network-based face detection system. Unlike similar systems which are limited to detecting upright, frontal faces, this system detects faces at any degree of rotation in the image plane.
We also have preliminary results for detecting faces which are rotated out of the image plane, such as profiles and semi-profiles.
The system employs multiple networks; the first is a "router" network which processes each input window to determine its orientation and then uses this information to prepare the window for one or more "detector" networks.
Neural Network-Based Face Detection
Henry A. Rowley, Shumeet Baluja, and Takeo kanade
IEEE Transactions on Pattern Analysis and Machine Intelligence, volume 20, number 1, pages 23-38, January 1998.