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Curvature Pruning Method in Online Handwriting Recognition

IP.com Disclosure Number: IPCOM000106654D
Original Publication Date: 1993-Dec-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Chefalas, TE: AUTHOR [+2]

Abstract

Disclosed is a pruning method based on the curvature of the writing of a stroke (or character). Some strokes are straight while others are curved. The curved strokes can curve in a clockwise or counter-clockwise direction. To maintain recognition accuracy, we prune conservatively. To prune a prototype, therefore, the feature difference between an unknown and prototype must be large enough that it would not eliminate the correct prototype.

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Curvature Pruning Method in Online Handwriting Recognition

      Disclosed is a pruning method based on the curvature of the
writing of a stroke (or character).  Some strokes are straight while
others are curved.  The curved strokes can curve in a clockwise or
counter-clockwise direction.  To maintain recognition accuracy, we
prune conservatively.  To prune a prototype, therefore, the feature
difference between an unknown and prototype must be large enough that
it would not eliminate the correct prototype.

      Many on-line, handwriting recognition systems use elastic curve
matching to match an unknown character against prototype (template)
characters [1,2].  Such systems usually represent the ways of writing
a character by a set of prototypes.  The speed of recognition is
inversely proportional to the number of prototypes an unknown is
matched against.  It is sometimes possible to prune (eliminate from
contention) prototypes that differ greatly from the unknown, thus
speeding computation in the recognition system.

      One of the parameters (measures) used in matching (comparing)
strokes in our system is the change in direction angle from one point
to the next.  For pruning we calculate the sum of the direction
changes over the sequence of points that describe the trajectory of
the stroke.  For example, the sum of the direction changes in writing
an "O" is about 360 º in the counter-clockwise direction or
-360 º in the clockwise direction.  This...