Browse Prior Art Database

Line Filter

IP.com Disclosure Number: IPCOM000078009D
Original Publication Date: 1972-Oct-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 3 page(s) / 45K

Publishing Venue

IBM

Related People

Kerchmar, K: AUTHOR

Abstract

In character recognition systems which must recognize characters written on a preprinted line, it is desirable to remove or filter the line data in order to simplify the recognition process. The arrangement shown in the drawing will act as such a filter.

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Line Filter

In character recognition systems which must recognize characters written on a preprinted line, it is desirable to remove or filter the line data in order to simplify the recognition process. The arrangement shown in the drawing will act as such a filter.

Video data is supplied during a succession of scanning sequences, from a data storage matrix to an element 3, which activates the line filter or not depending upon whether or not a line has been detected in data derived from a normalized data scan. This information governs element 5, which comprises sequential logic circuitry which keeps track of the X and Y coordinates of the normalized characters. The horizontal coordinate is created by the start of normalized character input, while the vertical coordinate is determined by the location of the line, previously detected. The primary function of element 5 is to control the operation of the line filter circuits within the normalized character.

The filter includes two elements 7 and 9 which may be termed "submachines", which are controlled by 5. Submachine 7 is responsible for the set of "others" characters, that is 0, 1, 3, 4, 5, 6, 8, 9. The decision for the set "others" is made on the information coming into the matrix above the line, and also on present status of submachine M2,7. If M0 successfully indicates the "others" type of the character start, then the action is taken in order to save the tail of characters (3, 5, 9), and the bottom of characters (0, 6, 8), and removes the line on both sides of the characters.

There are three possible line locations within the normalized character:
1) Line below the character is to be removed completely.
2) Line touching the bottom of the character, this case

yielding two possibilities:
(a) If the line is heavy, remove it from the character.
(b) If the line is thin, remove it only on the sides of

character.
3) Line within the character is to be removed.

Submachine 9, M2,7 is responsible for characters 2 and 7. The problem that occurs here is how to distinguish between tail of a 2 (to keep it), and the horizontal line in the character 7 (to remove it). This decision is very important for recognition performance (substitutions 2-7 or 7-2). Submachine M2,7 start can win over the submachine M0, regardless of the status of submachines M0, ALF and FDL 11 and Constants, Measurements, and Memory 13. The operation of the apparatus is as follows:

Submachine M0 did not start, but it is in the state which allows M2,7 to go in action if the status of ALF and Constant, Measurement, and Memory logics allows it. However, the first transition that M2,7 made is not the final decision, if the information is to be kept (as a tail of 2 or part of character) or to be removed (as a line in 7). The final decision is delayed due to the fact that M0 did not start.

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There are more transitions allowed between the M0 and M2,7 due to the various information inputs.

ALF (Amount Line Finding) logi...