Accession Number : ADA229036
Title : A Whole Word and Number Reading Machine Based on Two Dimensional Low Frequency Fourier Transforms
Descriptive Note : Doctoral thesis
Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
Personal Author(s) : O'Hair, Mark A.
Full Text : http://www.dtic.mil/get-tr-doc/pdf?AD=ADA229036
Report Date : DEC 1990
Pagination or Media Count : 135
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).
Descriptors : *FOURIER TRANSFORMATION , *WORD RECOGNITION , *OPTICAL SCANNING , *OPTICAL IMAGES , *READING MACHINES , COMPUTATIONS , ALGORITHMS , THESES , LOW FREQUENCY , SENSITIVITY , CLUSTERING , SCALE , COEFFICIENTS , WORDS(LANGUAGE) , SYMBOLS , NOISE , VOCABULARY , RANGE(DISTANCE) , NUMBERS , INVARIANCE , RADIUS(MEASURE) , CENTER OF GRAVITY , POSITION(LOCATION) , OPTICAL PROPERTIES , LIBRARIES , TWO DIMENSIONAL
Subject Categories : RECORDING AND PLAYBACK DEVICES
Distribution Statement : APPROVED FOR PUBLIC RELEASE