Qifeng Chen 0001 Dingzeyu Li Chi-Keung Tang 869-876 2012 CVPR https://doi.org/10.1109/CVPR.2012.6247760 https://doi.ieeecomputersociety.org/10.1109/CVPR.2012.6247760 conf/cvpr/2012 db/conf/cvpr/cvpr2012.html#ChenLT12