8. The method of claim 1 wherein: the method further comprises, prior to receiving the authentication request, engaging in an enrollment process for the user, the enrollment process including: displaying a plurality of test face images to the user; for each test face image of the plurality of test face images, receiving, from the user, a facial expression score for a particular emotion; and deriving a set of user-specific recognition properties based on the facial expression scores received in response to displaying the plurality of test face images to the user; and generating the set of one or more face images, each face image of the set of face images having the facial expression score for the particular emotion associated with that face image, the facial expression scores being specific to the user, includes referencing the derived set of user-specific recognition properties.
9. The method of claim 8 wherein: deriving the set of user-specific recognition properties based on the facial expression scores received in response to displaying the plurality of test face images to the user includes storing a plurality of 3-dimensional reference models corresponding to a subset of the plurality of test face images, each 3-dimensional reference model being stored in association with a facial expression score for one or more particular emotions received from the user with respect to a test face image generated from that 3-dimensional reference mode, each 3-dimensional reference model including a set of polygons, each polygon including a set of vertices and a texture map; and generating the set of one or more face images including referencing the derived set of user-specific recognition properties includes: performing a weighted 3-dimensional morphing operation between a 3-dimensional neutral face model and a 3-dimensional reference model of a face stored in association with a facial expression score received from the user for the particular emotion to yield a resulting 3-dimensional model, the weighted 3-dimensional morphing operation including morphing of the set of the vertices and texture maps of each polygon from the 3-dimensional neutral face model to the 3-dimensional reference model using the facial expression score as a weight; and rendering the resulting 3-dimensional model using 3-dimensional graphical rendering.