Ziheng Zhou 0003 Guoying Zhao 0001 Matti Pietikäinen 137-144 2011 CVPR https://doi.org/10.1109/CVPR.2011.5995345 https://doi.ieeecomputersociety.org/10.1109/CVPR.2011.5995345 conf/cvpr/2011 db/conf/cvpr/cvpr2011.html#ZhouZP11