Introduction - If you have any usage issues, please Google them yourself
facilitate the user s task. One such approach is the
object-related image retrieval. In the context of face
images, it is of interest to retrieve images based on
people s names and facial expressions. However, when
images of the database are allowed to appear at dif-
ferent facial expressions, the face recognition approach
encounters the expression-invariant problem, i.e. how
to robustly identify a person s face for which its learn-