UBC Theses and Dissertations

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UBC Theses and Dissertations

Real-time computer recognition of handprinted characters Chui, Timothy Loong-kei


A real-time character recognition system was developed to recognize upper case handprinted characters in a real-time small machine environment. The recognition system consists of two major components: namely, a data acquisition system and a pattern recognition system. The data acquisition system was designed and implemented to allow the real world data flow into the computer from a COMPUTER writing tablet in real time. The pattern recognition system was also designed and implemented to yield a decision on the input character in real time (user time). A curve optimization technique originally devised by Reumann and Witkam was modified to extract only the significant data that describes a character. Computations were minimized through mathematical simplifications, hardware-software trade-off, and special programming techniques at the machine level. In addition, the preprocessor operated concurrently with the data acquisition routine to reduce data storage requirements as well as to-provide fast response to handprinted inputs. A non-uniform quantization plane was proposed and implemented to discriminate pen directions. Stroke patterns of a character were recognized using a syntactic approach. Finally, recognized stroke patterns within a character were classified as one of the known pattern classes by two classification methods: dictionary look-up and a modified nearest neighbor rule, both guided by special geometric measurements on some character pairs. Character patterns were defined in the dictionary such that no user training or personalized dictionary is required for future use. A test was conducted using the ACM proposed upper case handprinted character set and a recognition rate of 98.3% was obtained from over 2300 characters of sizes varying from 1/4 inch tall to 3/4 inch tall from 10 people. It Is observed that the approach taken in this thesis can also be applied to recognized handprinted patterns other than the standard one proposed by the ACM.

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