ANSI INCITS 111-1986 Information Systems - Optical Character Recognition (OCR) - Matrix Character Sets for OCR-MA.pdf

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1、ADOPTED FOR USE BYTHE FEDERAL GOVERNMENTSEE NOTICE ON INSIDEANSI INCITS 111-1986 (R2002)(formerly ANSI X3.111-1986 (R1997) for Information Systems Optical Character Recognition (OCR) Matrix Character Sets for OCR-MAPUB 129This standard has been adopted for Federal Government use. Details concerning

2、its use within the Federal Government are contained in Federal infor- mation Processing Standards Publication 129, Optical Character Recognition (OCR) - Dot Matrix Character Sets for OCR-MA. For a complete list of the publications available in the Federal Information Processing Standards Series, wri

3、te to the Standards Processing Coordinator (ADP), Institute for Computer Sciences and Technology, National Bureau of Standards, Gaithersburg, MD 20899. ANSI X3.111-1986 American National Standard for Information Systems - Optical Character Recognition (OCR) - Matrix Character Sets for OCR-MA Secreta

4、riat Computer and Business Equipment Manufacturers Association Approved April 24, 1986 American National Standards Institute, Inc Abstract This standard provides the description of the positions and the sizes of dot patterns to be used in the application of matrix printing and recognition for optica

5、l character recognition systems. The three different groups, designated OCR-MAI, OCR-MA2, and OCR-MA3, are used to describe the character sets that can be achieved with different matrix resolutions. The four matrix resolutions covered by this standard are 5 X 7, 7 X 7, 7 X 9, and 9 X 9 (columns X ro

6、ws). AmericanNationalStandardApproval of an American National Standard requires review by ANSI that therequirements for due process, consensus, and other criteria for approval havebeen met by the standards developer.Consensus is established when, in the judgment of the ANSI Board of StandardsReview,

7、 substantial agreement has been reached by directly and materiallyaffected interests. Substantial agreement means much more than a simplemajority, but not necessarily unanimity. Consensus requires that all views andobjections be considered, and that a concerted effort be made toward theirresolution.

8、The use of American National Standards is completely voluntary; their existencedoes not in any respect preclude anyone, whether he has approved the standardsor not, from manufacturing, marketing, purchasing, or using products, processes,or procedures not conforming to the standards.The American Nati

9、onal Standards Institute does not develop standards and will inno circumstances give an interpretation of any American National Standard.Moreover, no person shall have the right or authority to issue an interpretation ofan American National Standard in the name of the American National StandardsInst

10、itute. Requests for interpretations should be addressed to the secretariat orsponsor whose name appears on the title page of this standard.CAUTION NOTICE: This American National Standard may be revised orwithdrawn at any time. The procedures of the American National StandardsInstitute require that a

11、ction be taken periodically to reaffirm, revise, or withdrawthis standard. Purchasers of American National Standards may receive currentinformation on all standards by calling or writing the American National StandardsInstitute.Published byAmerican National Standards Institute11 West 42nd Street, Ne

12、w York, New York 10036Copyright 1987 by Information Technology Industry Council (ITI)All rights reserved.No part of this publication may be reproduced in anyform, in an electronic retrieval system or otherwise,without prior written permission of ITI, 1250 Eye Street NW,Washington, DC 20005.Printed i

13、n the United States of AmericaForeword (This Foreword is not part of American National Standard X3.1 11-1986.) This standard presents matrix character sets for use in optical character recognition systems. These characters are meant to be similar in shape to those shown in American National Standard

14、 Character Set for Optical Character Recognition (OCR-A), ANSI X3.1 7-198 1. However, there are variations in conformance to OCR-A shapes for the dif- ferent sets of characters depending on the matrix resolution of the printed characters. The character set chosen will depend upon the application. Th

15、is standard defines the character shapes created by printing devices that generate characters by means of a matrix of dots with a contrasting background. Unlike OCR-A, where the emphasis is on reading performance, this standard has been written to reduce printing constraints to a level that will all

16、ow lower resolution printers to be usefully applied for OCR applications. Matrix printing is increasingly being used because of the ease of generating characters of this type with the use of digital computers. This need was recognized by the European Computer Manufacturers Association with the creat

17、ion of ECMA-5 1, Implementation of the Numeric OCR-A Font with 9 X 9 Matrix Printers, and ECMA-42, Alphanumeric Char- acter Set for 7 X 9 Matrix Printers. The need was also recognized by the German Stan- dards Institute with the creation of DIN 66008, Font A for Optical Character Recog- nition; Char

18、acter Representation by Dots within 9 X 9 Matrix Dimensions. As in this standard, the characters were defined by a specific combination of “dots” on a fixed grid. This American National Standard limits the printer to a specific placement of dots on a grid, and the print quality requirements that sha

19、ll be met regardless of the dot matrix used. Three different groups (OCR-MAl, OCR-MA2, and OCR-MA3) are defined and the char- acter sets for these groups are shown in Table 1. OCR-MA1 can be met with 5 X 7, 7 X 7, 7 X 9, and 9 X 9 matrices. OCR-MA2 can be met with 7 X 7,7 X 9, and 9 X 9 matrices. Th

20、e OCR-MA3 characters can be obtained with the 7 X 9 and the 9 X 9 matrices. In all cases, the 9 X 9 matrix is the recommended matrix for the best scanning results. The 7 X 9 matrix is the first alternate, the 7 X 7 is the second alternate, and the 5 X 7 is the last alternate recommended. The 9 X 9 m

21、atrix characters, illustrated in Figures 7 through 58, and the 7 X 7 matrix characters, illustrated in Figures 110 through 139, are designed to increase printer throughput by imposing the restriction that there are no dots on adjacent horizontal positions. Matrices with resolutions of higher densiti

22、es than 9 X 9 are not specifically covered in this standard. However, higher resolution printers can create characters that meet the require- ments of this standard. Often this can be accomplished by using a group of small dots closely spaced to create the same effect as one larger dot. High resolut

23、ion matrix printers can also be used to create OCR-A characters that fall within the quality requirements and characters shape requirements of ANSI X3.17-1981. Suggestions for improvement of this standard will be welcome They should be sent to the Computer and Business Equipment Manufacturers Associ

24、ation, 3 11 First Street, NW, Suite 500, Washington, DC 20001 This standard was processed and approved for submittal to ANSI by Accredited Standards Committee on Information Processing Systems, X3. Committee approval of the standard does not necessarily imply that all committee members voted for its

25、 approval. At the time it approved this standard, the X3 Committee had the following members Edward Lohse, Chair Richard Gibson, Vice-Chair Catherine A. Kachurik, Administrative Secretary Organization Represented American Express. . . . . . . . . . , . . . . . . . . American Library Association. . .

26、 . . . . . . . . . . American Nuclear Society . . . . . . . . . . . . . . . AMP Incorporated . . . . . . . . . . . . . . . . . . . Association for Computing Machinery , . . . . . . . . . . . . . Association of the Institute for Certification of Computer Professionals . . . . . . . . . AT 9 n ; - - X

27、 X X X X X - X - - x x x x x x x x x x x x x x x x x x x x x x - x x x x x - x - x - x - X - x - x - X - x x x x x - x x x - x x x - x - x x x - x - x x x x x - x x x x x x x x x x x x x x x x x x x x x - x - x - x 13 AMERICAN NATIONAL STANDARD X3.1 1 l-1986 4.2.2 Character SPACE. The character SPAC

28、E is a blank area in a line of print, having a width equal to the character pitch (if the characters are printed 10 to the inch, the character pitch is l/IO inch (2.54 mm). When a blank area is bounded by narrow characters (the first or last columns in the matrix do not contain dots) the narrow char

29、acters shall be assigned a width of 0.069 inch (1.75 mm) for the purpose of determin- ing the number of SPACE characters between the printed characters. 4.3 Use of Characters. Data interchange applications shall follow the nominally assigned information con- tent of ANSI X3.4-1986 (ASCII). Three spe

30、cial charac- ters have been provided that are recommended for use when control symbols are required. These symbols are hook ( J ), fork ( y ), and chair ( rl ). 4.4 Relative Character Spacing, Details of character spacing are addressed in ANSI X3.93M-1981. For char- acter positioning, a reference li

31、ne for vertical position- ing and a reference line for horizontal positioning shall be used. The reference line for vertical positioning, re- lative to line spacing, is the “baseline.” The reference line for horizontal positioning, relative to line spacing, is the “centerline.” In all cases, for OCR

32、-MA, the base- line shall be the bottom horizontal line in any matrix, indicated by position 0.0000 inch (0.000 mm) in Fig- ures 2 through 5, and the centerline shall be the mid- dle vertical line in any matrix, indicated by the position that marks 0.0275 inch or 0.698 mm in the figures. The charact

33、ers in a row are properly aligned verti- cally when their baselines are collinear. Certain charac- ters are displaced above the common baseline. The ver- tical locations of these characters are determined by the dot placement on the matrices. 4.4.1 Line Spacing. In order to maintain an ade- quate se

34、paration between lines of characters, the nomi- nal number of lines per inch (25.4 mm) shall not ex- ceed 6. To ensure a sufficient separation between lines of characters, the minimum distance from the lowest vertical extension of one line of characters to the highest vertical extension of the next

35、lower line of char- acters shall be 0.025 inch (0.64 mm). The line spacing that can be successfully scanned by an OCR reader differs from reader to reader The user is advised to con- sult with the OCR equipment manufacturer when the line spacing is denser than 3 lines per inch (25.4 mm). 4.4.2 Chara

36、cter Spacing. Character spacing less than the minimum spacing specifications may prevent the OCR reader from totally recovering after reading the previous character. Character spacing that approaches the maximum allowable spacing may result in a recog- nized character space. The nominal spacing betw

37、een the vertical centerlines of adjacent characters should 14 be 0.100 inch (2.54 mm) to 0.110 inch (2.79 mm) for efficient printing and equipment reading of matrix OCR-MA characters. Minimum spacing between the vertical centerlines of any adjacent characters shall be 0.090 inch (2.29 mm). Maximum s

38、pacing between the vertical centerlines of any adjacent character shall be 0.180 inch (4.57 mm). The user is advised to consult with the OCR equipment manufacturer to determine the readers character spacing specifications. 4.4.3 Minimum Character Separation. The mini- mum distance between the outsid

39、e edge of any dot printed in the last used column of a character matrix and the outside edge of any dot printed in the first used column of the next character matrix shall be 0.014 inch (0.36 mm). 4.5 Print Quality. For details of print quality, see ANSI X3.99-1983. In general, the print quality for

40、 OCR-MA characters shall meet the requirements of quality rangey as stated in ANSI X3.99-1983. Excep- tions to ANSI X3.99-1983 are detailed in this section. 4.5.1 Measurement of Print Image Contrast. Since matrix characters are created with dots on a specific matrix, measurements of the contrast as

41、related to the background medium (print contrast signal) and mea- surements of contrast within a character (contrast vari- ation ratio) shall be taken from the nominal centerpoint location of the dots on the matrix. This means that cer- tain features within the character body that would be considere

42、d nonallowable voids in OCR-A shall be al- lowed in OCR-MA. A void that falls on a line between the nominal centerpoints of two adjacent dots shall be allowed. This type of void may occur on a horizontal line between dots located in adjacent columns, on a vertical line between dots located in adjace

43、nt rows, or on a sloped line between dots located in different col- umns and rows. An example of this condition can be observed from Figures 13, 116, and 146, showing the dot locations for the character 7. 4.5.2 Print Contrast Signal (PCS). The print con- trast signal (PCS) is an expression that rel

44、ates the con- trast between selected points of interest within a printed character, and the background medium. The PCS value of a Point P is defined by the equation: PCS =Rw-R, RW where R, = the maximum reflectance of the background medium found within 0.060 inch (1.50 mm) of the edge of a printed c

45、haracter. R, = the reflectance from a measured area centered on Point P, the nominal centerpoint location of any of the dots that form the character. AMERICAN NATIONAL STANDARD X3.11 l-l 986 For OCR-MA, the reflectance values for R, and R, shall be measured within a circular area (aperture) of 0.008

46、 inch (0.20 mm) in diameter. The minimum PCS of all dots with a nominal dot size equal to or greater than 0.014 inch (0.36 mm) shall be 0.50. The minimum PCS of all dots with a nominal dot size less than 0.014 inch (0.36 mm) and equal to or greater than 0.012 inch (0.30 mm) shall increase proportion

47、ally from 0.50 for a 0.014-inch (0.36-mm) dot to 0.60 for a 0.012-inch (0.30-mm) dot. This is shown graphically in Figure 6. 4.5.3 Contrast Variation Ratio. The variation of contrast in a character is expressed by the contrast variation ratio (CVR), which is defined as: CvR = PCs max PCS min where P

48、CS min = the lowest PCS level of an area covered by a circle 0.008 inch (0.20 mm) in diameter, located on any nominal center- point location of the dots in a character. PCS max = the highest PCS level of an area covered by a circle 0.008 inch (0.20 mm) in diameter, located on any nominal center- poi

49、nt location of the dots in a character. The CVR shall be less than or equal to 1.8. 4.5.4 Voids. Voids are areas where the printing pro- cess does not deposit sufficient material on the printed media. Voids have significantly higher reflectance than other areas of the printed image. Voids shall be allowed if they do not reduce the PCS min, as described in 4.5.3, below a value of 0.50. 4.5.5 Spot. Spots are areas located within 0.060 inch (1 SO mm) of a printed character, that contrast with the printed media. Spots may be allowable or nonallowable based on size and PCS level. For adjac