Preprocessing and Image Enhancement Algorithms for a Form-based Intelligent Character Recognition System

A Form-based Intelligent Character Recognition (ICR) System for handwritten forms, besides others, includes functional components for form registration, character image extraction and character image classification. Needless to say, the classifier is a very important component of the ICR system. Automatic recognition and classification of handwritten character images is a complex task. Neural Networks based classifiers are now available. These are fairly accurate and demonstrate a significant degree of generalisation. However any such classifier is highly sensitive to the quality of the character images given as input. Therefore it is essential that the preprocessing components of the system, form registration and character image extraction, are well designed. In this paper we discuss the form image registration technique and the image masking and image improvement techniques implemented in our system as part of the character image extraction process. These simple yet effective techniques help in preparing the input character image for the neural networks-based classifiers and go a long way in improving overall system accuracy. Although these algorithms have been discussed with reference to our ICR system they are generic in their applicability and may find use in other scenarios as well.