Among the many developed techniques for biometric recognition, face analysis seems to be the most promising and interesting modality. Nonetheless, there are still many open problems which need to be faced as well. For example, the information conveyed by faces (in fact too much) must be selectively extracted to obtain useful hints for recognition. The choice of optimal resolution of the face within the image, face registration and facial feature extraction are still open issues. This not only requires to devise new algorithms but to determine the real potential and limitations of existing techniques. It turns out that all methods based on the same biometric measurements have the same intrinsic limitations, which can be only overcome by the adoption of a multi-modal or multi-algorithmic approach.