Browse Prior Art Database

Fast Clipping Level Determination in a Character Recognition System

IP.com Disclosure Number: IPCOM000091337D
Original Publication Date: 1968-Jan-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 3 page(s) / 34K

Publishing Venue

IBM

Related People

Norman, RJ: AUTHOR

Abstract

The character recognition system has scan control 10, scanner 12 and recognition circuits 14. The remaining apparatus rapidly determines a threshold for use in digitizing the video signal from the scanner so that a digitized video signal is passed to recognition circuits 14. The character recognition system has two modes of scanning, i.e., curve follow and bar code. Bar code scanning consists of making three horizontal scans and one vertical scan through a character. Based upon the position of the intersects between the scanning beam and the character, the character can be recognized. Curve follow scanning is accomplished by directing the scanning beam to follow the outside contour of the character.

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Fast Clipping Level Determination in a Character Recognition System

The character recognition system has scan control 10, scanner 12 and recognition circuits 14. The remaining apparatus rapidly determines a threshold for use in digitizing the video signal from the scanner so that a digitized video signal is passed to recognition circuits 14. The character recognition system has two modes of scanning, i.e., curve follow and bar code. Bar code scanning consists of making three horizontal scans and one vertical scan through a character. Based upon the position of the intersects between the scanning beam and the character, the character can be recognized. Curve follow scanning is accomplished by directing the scanning beam to follow the outside contour of the character.

For fast scanning through a line, the first character in the line is curve followed to determine the vertical position of the line end the average black level of the character. During this curve follow mode of operation, the scan control enables And 16 to pass the video signal to voltage storage device 18. The latter then stores the average level of black as the character is curve followed. Once a character is curve followed, the scan control switches to bar code scanning and proceeds to bar code scan the remaining characters in the line from right to left.

The bar code scan pattern is such that the horizontal lines extend far enough to the left so that they not only pass through the character being recognized but also intersect the right-hand edge of the next character to be scanned. By detecting the right-hand edge of the next character, the scan control can shift the scanning to the next character after a character is recognized.

The average level stored in device 18 is used as a threshold in voltage discriminator 20, used to digitize the video signal from scanner 12. The video signal is also digitized by a minimum threshold level operating on voltage discriminator 22. The outputs from discriminators 20 and 22 are logically combined in Or 24 and are normally passed by And 26 and Or 28 to circuits 14 where the digitized video signal is analyzed.

As the bar code scanning proceeds from character to character the succeeding characters can occasionally be darker and have associated ink splatter which causes errors. The errors would be the result of discriminat...