A multi-stage infrared (IR) image-based tracking system is provided that
accurately identifies and tracks targets across a variety of different
situations and environmental conditions. The system includes primary and
secondary trackers. The secondary tracker supports the primary tracker by
identifying and tracking targets when the primary tracker loses or fails
to identify one or more targets, and helps the primary tracker reacquire
valid targets. In an exemplary embodiment of the invention, the primary
tracker is a correlation-based tracker, and the secondary tracker is a
feature-based tracker. A prescreener is also included, which operates
concurrently with the correlation-based and feature-based trackers to
generate a list of possible targets. The list can be used to provide a
confidence level for the probable targets identified by each of the
primary and secondary trackers.