Takuma Yamaguchi Minoru Maruyama Hidetoshi Miyao Yasuaki Nakano Digit recognition in a natural scene with skew and slant normalization. 168-177 2005 7 IJDAR 2-3 http://dx.doi.org/10.1007/s10032-004-0136-1 db/journals/ijdar/ijdar7.html#YamaguchiMMN05