An Automatic Face Identification System Using Flexible Appearance Models

Abstract

We describe the use of flexible models for representing the shape and grey-level appearance of human faces. These models are controlled by a small number of parameters which can be used to code the overall appearance of a face for image compression and classification purposes. The model parameters control both inter-class and within-class variation. Discriminant analysis techniques are employed to enhance the effect of those parameters affecting inter-class variation, which are useful for classification. We have performed experiments on face coding and reconstruction and automatic face identification. Good recognition rates are obtained even when significant variation in lighting, expression and 3D viewpoint, is allowed. Human faces display significant variation in appearance due to changes in expression, 3D orientation, lighting conditions, hairstyles and so on. A successful automatic face identification system should be capable of suppressing the effect of these factors allowing any face image to be rendered expression-free with standardised 3D orientation and lighting. We describe how the variations in shape and grey-level appearance in face images can be modelled, and present results for a fully automatic face identification system which tolerates changes in expression, viewpoint and lighting.