1-Dimensional and Pseudo 2-Dimensional HMMs for the Recognition of German Literal Amounts

  • Authors:
  • Rolf-Dieter Bippus

  • Affiliations:
  • -

  • Venue:
  • ICDAR '97 Proceedings of the 4th International Conference on Document Analysis and Recognition
  • Year:
  • 1997

Quantified Score

Hi-index 0.00

Visualization

Abstract

Hidden Markov Models (HMMs) are fre-quently used in off-line cursive script recognition. In most cases the script is processed strictly from left to right, yielding a sequence of feature vectors fed into the HMM recognizer. In order to achieve good recognition results, more or less complex normalization has to be performed on the script beforehand to reduce the effects of writer variability. Taking the example of German literal amounts, especially ruler-line estimation and height normalization becomes a difficult task due to the often extremely long words. In many cases the assump-tion of straight ruler lines does not hold. Thus it would be advantageous to integrate normalization into the rec-ognition process. We present two approaches using regular one-dimensional HMMs in comparison to Pseudo two-dimensional HMMs (P2DHMM). Preprocessing is basically identical for both approaches. In the case of P2DHMMs, however, we use a much simpler ruler line estimation scheme. Under otherwise similar conditions, the P2DHMMs have proved to be slightly superior to the regular HMMs in first experiments. The performance could still be enhanced by combining the results from both recognizers.