Using Colour Templates for Target Identification and Tracking

Abstract

A surveillance system is presented which uses colour cues to track people moving in sparse crowd scenes. The erratic motion of the targets, together with their changeable outline, means that they are conventionally difficult to model. However, by examining the colours present in an object in a given frame of a sequence, and looking for these in a later frame, identification and tracking are achieved. The colours are transformed into a template space in which it is easy to match objects to those held in a database, so that even when a person is occluded or disappears totally from view they may be re-located as soon as they can be clearly seen again. A hierarchical approach to template storage and searching reduces the effort required to search through the database and ensures that the system is efficient even with a database containing the templates of hundreds of people. Since work is carried out on a moving sequence, the problems of changing object shape and maintaining colour constancy are minimised by allowing for small changes in these parameters between frames and by continually updating each object’s template.

Supported by a SERC award.