Date of Award
12-1990
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Department of Electrical and Computer Engineering
Abstract
The Fourier transform is investigated as a means for developing an optical reader capable of reading a large vocabulary without segmenting the image of a word into individual characters. The reader is capable of reading printed and cursive font styles, is scale invariant, and is substantially insensitive to noise. The image of a particular word is treated as a single symbol; the two dimensional low frequency Fourier coefficients (assuming n coefficients are calculated) define the word's location on an n dimensional hypersphere of unit radius. The distance between individual locations (words) categorizes similar and dissimilar words. The smaller the distance, the more similar images are. Multiple images of a word using various font styles form a unique cluster on the surface of the hypersphere. The distance between clusters (different words) is greater than the distance across a cluster (same word in different font styles). Therefore, by using the centroid of these clusters to build a library of words, input or test words match to the nearest cluster centroid using a minimum distance calculation. This algorithm is capable of correctly recognizing at least 5000 words using 24 various font styles (120,000 individual images).
AFIT Designator
AFIT-DS-ENG-90D-01
DTIC Accession Number
ADA229036
Recommended Citation
O'Hair, Mark A., "A Whole Word and Number Reading Machine Based on Two Dimensional Low Frequency Fourier Transforms" (1990). Theses and Dissertations. 7817.
https://scholar.afit.edu/etd/7817