Hiroyuki Ishida Tomokazu Takahashi Ichiro Ide Hiroshi Murase A Hilbert warping method for camera-based finger-writing recognition. 1-5 2008 ICPR http://dx.doi.org/10.1109/ICPR.2008.4761380 conf/icpr/2008 db/conf/icpr/icpr2008.html#IshidaTIM08