Faisal Shafait Joost van Beusekom Daniel Keysers Thomas M. Breuel Background variability modeling for statistical layout analysis. 1-4 2008 ICPR http://dx.doi.org/10.1109/ICPR.2008.4760964 conf/icpr/2008 db/conf/icpr/icpr2008.html#ShafaitBKB08