DETECTING WHEN THE PEN IS NOT WRITING
The trajectory obtained by the pen tip tracker and the filter is not
suitable to perform handwriting recognition since most of the
recognition systems up to date assume that their input data is only
formed by pen-down strokes. The system finds the position of the pen's
ballpoint and checks for the presence of ink in this place. The ballpoint
detector assumes that the pen tip is rougly conical in shape, in order
to look for its projection onto the image plane. The following figure shows
the points in which the boundaries of the pen tip were found using simple
edge detection masks. The axis of the pen tip is located and the position
of the ballpoint and the finger are found by using the image's brigthness
profile along this axis.
The image's brigthness at and around the ballpoint position is measured
in order to detect the presence of ink. Each point of the trajectory is
later classified as pen up or pen down depending on this ink detection.
In the page corresponding to results we show
the performance of this algorithm working on several hadwriting sequences.
Return to the pen interface page.
Mario Enrique Munich
- mariomu AT vision DOT caltech DOT edu