An image processing apparatus for tracking faces in an image stream iteratively receives a new acquired image from the image stream, the image potentially including one or more face regions. The acquired image is sub-sampled (112) at a specified resolution to provide a sub-sampled image. An integral...http://www.google.com.au/patents/US20090208056?utm_source=gb-gplus-sharePatent US20090208056 - REAL-TIME FACE TRACKING IN A DIGITAL IMAGE ACQUISITION DEVICE