Technique operates regardless of pattern rotation, translation or magnification and successfully detects out-of-register patterns. It improves accuracy and reduces cost of various optical character recognition devices and page readers and provides data input to computer

Hong, J. P.

English

NASA Technical Reports Server

June 1971
	
Brief 71-10187 
NASA TECH BRIEF 
NASA Pasadena Office. 	 . 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a aubscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the. Tech Brief program may 
be directed to the Technology. Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Pattern Recognition Technique 
A new, reliable technique for pattern recognition, 
especially of alphanumeric characters, successfully 
detects out-of-register patterns. It operates regardless 
of pattern rotation, translation, or magnification.
must be considered together in the design of an 
optimum system. 
The system illustrated uses a random number 
generator feeding a flying-spot scanner to generate 
Flying-	 H CRT Spot Scanner Auto	 Density	 _____	 Pattern Probability 	 Memory: Gain	 Function	 Storage Control	 Computer 
Film .
Random 
Number  
Generator
Photomultipl ier
Comparator 
(Statistical 
Algorithm)
Output Category 
The technique can improve the accuracy and re-
duce the cost of various optical character recogni-
tion devices and page readers, and could be used to 
provide data input to a computer. 
The technique is based on determining the proba- 
bility density function (PDF) of intersection lengths 
of random lines with a given pattern. Since the PDF 
is a function of pattern shape only, coupling it 
with an identification algorithm yields efficient 
statistical pattern classification. 
Pattern recognition is essentially a two-step process. 
First, the pattern must be converted into a statistically 
convenient form. This process, usually called feature 
extraction, is most often performed by the direct 
measurement of some quality of the pattern. Second, 
the data thus obtained must be manipulated and 
the pattern category determined. The two steps
random lines on a CRT. These lines crisscross the 
pattern and are detected on a photomultiplier grid 
or retina. The output of the retina, accumulated 
over a period of time, is an empirical PDF that is 
unique for each pattern class. The PDF itself, or 
the function resulting from a secondary algorithm, 
is applied to the comparator, and a statistical 
algorithm is applied to obtain a pattern classi-
fication. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: TSP71-10187 (continued overleaf) 
MW
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States 	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19710000186 2020-03-17T02:24:33+00:00Z
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to: 
Patent Counsel 
Mail Code 1 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Source: J. P. Hong of

Caltech/JPL
under contract to

NASA Pasadena Office

(NPO- 11337)


Pattern recognition technique

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