16. The storage of claim 13 , wherein the method further comprises: determining a discriminative power for each of a plurality of AUs based on statistical data; selecting a set of AUs representing each of a plurality of emotion labels, based on the discriminative power for each of the plurality of AUs; and storing the selected set of AUs associated with each of the plurality of emotion labels as AU strings.
16. The storage of claim 13 , wherein the method further comprises: determining a discriminative power for each of a plurality of AUs based on statistical data; selecting a set of AUs representing each of a plurality of emotion labels, based on the discriminative power for each of the plurality of AUs; and storing the selected set of AUs associated with each of the plurality of emotion labels as AU strings. 17. The storage medium of claim 16 , wherein the discriminative power for each of the plurality of AUs indicates a probability of each AU belonging to one of the plurality of emotion labels.