Design and implementation of a portable omnifont reading aid for the blind

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.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Electrical Engineering

Department dc:contributor.department

Electrical Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1990

Author dc:creator

• Asimopoulos, Nikos

Chair dc:contributor.committeechair

• Nadler, Morton

Committee members dc:contributor.committeemember

• Besieris, Ioannis M.
• Gray, Festus Gail
• Claus, Richard O.
• Smith, Eric P.

• visual impairment
• Quasi-Topological Codes
• handheld scanners

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-09162005-115042

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/39385