As a general first step in a recognition system, preprocessing plays a very important role and can directly affect the recognition
performance. This Chapter proposes a new preprocessing technique for online handwriting. The approach is to first remove the
hooks of the strokes by using changed-angle threshold with length threshold, then filter the noise by using a smoothing technique,
which is the combination of the Cubic Spline and the equal-interpolation methods. Finally, the handwriting is normalised.
Section 2.1 introduces the problems and the related techniques of the preprocessing for online handwritten data. Section 2.2
describes our preprocessing approach for online handwritten data. The experimental results with discussions are showed in
Section 2.3. The summary of this chapter is given in the last section.