Discrete Single Vs. Multiple Stream HMMs: A Comparative Evaluation of Their Use in On-Line Handwriting Recognition of Whiteboard Notes
Joachim Schenk, Stefan Schwärzler, Gerhard Rigoll · 2008
In this paper we study the influence of quantization on the features used in on-line handwriting recognition in order to apply discrete single and multiple stream HMMs. It turns out that the separation of the features in statisticaly independent streams influences the performance of the recognition system: using the discrete “pressure” feature as an example, we show that the statistical dependencies between the features are as important as their proper quantization. In an experimental section we show that a continuous state-of-the-art system for on-line handwritten whiteboard note recognition can be outperformed by r = 2.0 % relative in word level accuracy using a three stream discrete HMM system with well chosen streams. A relative improvement of r = 4.5 % can be achieved when comparing a single stream HMM system with the best performing mutliple stream HMM system.