Tzu-Yuan Chang Yusuke Takiguchi Minoru Okada Physical Structure Segmentation with Projection Profile for Mathematic Formulae and Graphics in Academic Paper Images. 1193-1197 2007 conf/icdar/2007 ICDAR http://doi.ieeecomputersociety.org/10.1109/ICDAR.2007.208 db/conf/icdar/icdar2007.html#ChangTO07