Masakazu Iwamura Ryo Niwa Akira Horimatsu Koichi Kise Seiichi Uchida Shinichiro Omachi Layout-free dewarping of planar document images. 1-10 2009 DRR http://dx.doi.org/10.1117/12.806122 conf/drr/2009 db/conf/drr/drr2009.html#IwamuraNHKUO09