Title page for ETD etd-09162005-115042
|Type of Document
||Design and implementation of a portable omnifont reading aid for the blind
|Besieris, Ioannis M.
|Claus, Richard O.
|Gray, Festus Gail
|Smith, Eric P.
- visual impairment
- Quasi-Topological Codes
- handheld scanners
|Date of Defense
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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