Takahiro Otsuka Jun Ohya Recognizing Abruptly Changing Facial Expressions from Time-Sequential Face Images. 808-813 1998 conf/cvpr/1998 CVPR http://doi.ieeecomputersociety.org/10.1109/CVPR.1998.698697 db/conf/cvpr/cvpr1998.html#OtsukaO98