Contour-based object tracking with gradient-based contour attraction field

Object tracking is a problem which is very often addressed by various approaches, including background subtraction, visual constancy or geometric flow. The contribution of this paper is twofold. First, it proposes an enhanced feature-weighted gradient, enhancing the contours of the object characterized by this feature, and attenuating the gradient amplitude wherever the feature is not found. The second, and main contribution, is a new integrator for active-contours based tracking. It uses the gradient alongside the object contours and generates a bidirectional attraction field. The combination of the contour tracking and the weighted gradient is illustrated on the driver´s-face tracking problem, where the illumination conditions (brightness, colour) change as the vehicle passes through different environments.