1. A method, comprising: representing images as tensors; and deriving orthogonal tensor projections to characterize image features for recognizing a person's face across different images containing the person's face, each of the orthogonal tensor projections being orthogonal to a remainder of the orthogonal tensor projections, and the orthogonal tensor projections minimizing dissimilarities between different instances of the person's face and maximizing dissimilarities between the person's face and faces of other people.