Writing speed normalization for on-line handwritten text recognition

Pen-based interfaces aim at improving the man-machine interaction of many portable systems. While statistical models can be used to learn pen position sequences, they suffer from the huge variability exhibited by the speed of writing. To improve performance, invariance to the writing speed is needed. Trace segmentation is a technique that can be used to normalize the writing speed. This method is controlled by a parameter called resampling distance. A study of the resampling distance is presented here, along with another approximation to the writing speed normalization called "derivatives normalization". The improvement using trace segmentation was 193% relative to the baseline, whilst the improvement using derivatives normalization was 47.3% relative.