Recognizing on-line handwritten alphanumeric characters through flexible structural matching

Speed, accuracy, and #exibility are crucial to the practical use of on-line handwriting recognition. Besides, extensibility is also an important concern as we move from one domain to another which requires the character set to be extended. In this paper, we will propose a simple yet robust structural approach for recognizing on-line handwriting. Our approach is designed to achieve reasonable speed, fairly high accuracy and su$cient tolerance to variations. At the same time, it maintains a high degree of reusability and hence facilitates extensibility. Experimental results show that the recognition rates are 98.60% for digits, 98.49% for uppercase letters, 97.44% for lowercase letters, and 97.40% for the combined set. When the rejected cases are excluded from the calculation, the rates can be increased to 99.93%, 99.53%, 98.55% and 98.07%, respectively. On the average, the recognition speed is about 7.5 characters per second running in Prolog on a Sun SPARC 10 Unix workstation and the memory requirement is reasonably low. With this simple yet robust structural approach, we already have an e!ective and e$cient on-line character recognition module. This module will be used as part of a larger system, a pen-based mathematical equation editor, which is being developed by the authors using a syntactical pattern recognition approach. ( 1999 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved.