This gang of motley characters are the eigenfaces expressed though time, so I can see what kind of changes each vector represents in my eigenface-space. If you look closely they tend to express lighting changes, expressions, face shape and pose (head rotation) often jumbled together in some strange form. The next target is to separate out these ‘modes of change’ into clean vectors, so you only see expression, or only lighting changes etc in each vector. Then it becomes possible to build an appearance model which understands an incoming image in ways which are useful. e.g. ‘This is a face which looks like bob, he seems to be smiling, and the light is coming from the left’. Well, that’s the theory anyway.