Type of Document	Dissertation
Author	Asimopoulos, Nikos
URN	etd-09162005-115042
Title	Design and implementation of a portable omnifont reading aid for the blind
Degree	PhD
Department	Electrical Engineering
Advisory Committee	Advisor Name Title Nadler, Morton Committee Chair Besieris, Ioannis M. Committee Member Claus, Richard O. Committee Member Gray, Festus Gail Committee Member Smith, Eric P. Committee Member
Keywords	visual impairment Quasi-Topological Codes handheld scanners
Date of Defense	1990-07-11
Availability	restricted
Abstract The design and implementation of a handheld scanner that can help sight-impaired or even blind users to manually scan and read text is discussed in this dissertation. A thorough investigation of all the elements involved in such a system is presented and optimal solutions are proposed. A unique velocity compensation technique based solely on optical information obtained by the scanning device is discussed and a real time segmentation technique based on topological properties (Quasi-Topological Codes) of connected segments is presented. A skew detection algorithm is discussed that can trace typed and printed text manual1y scanned with skew up to 15 degrees and can guide blind users to properly scan a document. Real time extraction of quasitopological codes for automatic text recognition and the hardware implementation is also discussed in this work. A hierarchical optical character recognition method is proposed which is based on syntactic and metric analysis of the Quasi-Topological Codes and their position in the scanned image. The proposed method can recognize characters stretched to approximately two times their original width or rotated by a few degrees. Finally, an automated iterative learning process is discussed which includes generalization of the recognition logic and dynamic adaptation of the syntactic and metric recognition rules.
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