Extracting facial features by an inhibitory mechanism based on gradient distributions

The extraction of facial features is a fundamental and crucial step in most face detection and recognition systems. Here a set of approaches are proposed for extracting internal and external facial features in a grey-level images containing single or multiple faces of various sizes at different locations without any restriction on the background. These approaches are distinctive in several aspects: the use of some rarely exploited photometric properties as the basis for facial features extraction, a novel metrics on radial symmetry of gradient orientations, an inhibitory mechanism for extracting internal facial features, and a simple mechanism for external ones.