This paper presents an improved real-time head tracking method

which can realize robust tracking of a person's translation and turning around with a black/white camera. This method consists of two main steps: block feature based head tracking

and head geometry based correction. The block feature based tracking only uses low-level image information and does not rely on the models of different objects

thus it can be used to track the free motion of the head. The correction step is introduced to address the shift caused by errors accumulating of block tracking. This step measures the displacements of the head contour in the tracking window of current image

and hereby to correct the results of block tracking. Moreover

to improve the performance of block tracking during person's turning around

we introduce a cylindrical model to approximate head

and extract and track features in the warped cylindrical surface. The resulting system provides robust and precise tracking over long sequence on a 350 megahertz microcomputer

and operates at 30 frames per second with the tracking window size of 120×180 pixels and the tracking sets of 80 features.