BS 6616-1986 Specification for paper and print for optical character recognition (OCR)《光学字符识读(OCR)用纸和印刷规范》.pdf

1、BRITISH STANDARD BS 6616:1986 Specification for Paper and print for optical character recognition (OCR) UDC 681.327.12:676.22 + 655.244.07BS6616:1986 This British Standard, having been prepared under the directionof the Office and Information Standards Committee, was published underthe authority of

2、the BoardofBSI and comes intoeffecton 31October1986 BSI 07-1999 The following BSI references relate to the work on this standard: Committee reference OIS/23 Draft for comment83/63637 DC ISBN 0 580 14537 9 Committees responsible for this British Standard This British Standard was entrusted by the Off

3、ice and Information Standards Committee (OIS/-) to Technical Committee OIS/23, upon which the following bodies were represented: Association for Payment Clearing Services British Computer Society Ltd. British Paper and Board Industry Federation (PIF) British Printing Industries Federation British Te

4、lecommunications plc Business Equipment Trade Association Electricity Supply Industry in England and Wales Her Majestys Stationery Office HM Treasury (Central Computer and Telecommunications Agency) Institute of Printing National Girobank Amendments issued since publication Amd. No. Date of issue Co

5、mmentsBS6616:1986 BSI 07-1999 i Contents Page Committees responsible Inside front cover Foreword ii Section 1. General 1 Scope 1 2 Definitions 1 3 Classification 4 Section 2. Paper quality 4 Paper opacity 5 5 Reflectance factor R o 5 6 Freedom from dirt 5 Section 3. Print quality 7 Print quality cha

6、racteristics 6 Section 4. Character positioning 8 All character sets 7 9 Character sets OCRA and OCRB 7 Appendix A Guidance on paper properties 11 Appendix B Method for measurement of reflectance factor R o 11 Appendix C Methods for determining the quality of print for optical character recognition

7、12 Appendix D Method for visual checking of print quality of character sets OCRA and OCRB 13 Appendix E Method for construction of a COL gauge for character sets OCRA and OCRB 15 Figure 1 Illustration of lot, sheet, specimen and sample 2 Figure 2 Character skew 8 Figure 3 Character separation and ch

8、aracter spacing within a line 8 Figure 4 Line boundary 8 Figure 5 Printing area, clear area and margin 9 Figure 6 Character alignment within a line 9 Figure 7 Line separation and line spacing 10 Figure 8 COL gauge in its “best fit” position 13 Figure 9 Voids 14 Figure 10 Edge irregularities 14 Figur

9、e 11 Spots 15 Figure 12 Special situations at minimum and maximum COL 16 Figure 13 Special corner at maximum COL 16 Table 1 Tolerances on dimensions for character sets OCRA and OCRB 6 Table 2 Fairing radii 15 Publications referred to Inside back coverBS6616:1986 ii BSI 07-1999 Foreword BS6616 was pr

10、epared under the direction of the Office and Information Standards Committee at the request of the clearing banks that arose as a result of the automation of the credit clearing system, involving the optical reading of bank giro credit vouchers. However, the standard is of general relevance to other

11、 optical reading applications. This standard is based on ISO1831:1980. The United Kingdom voted against ISO1831 when it was circulated as a Draft International Standard (DIS), not for reasons of technical content but because it was considered that ISO1831 was not sufficiently precise for use as a sp

12、ecification. BS6616 differs principally from ISO1831 in that the computer-aided method for determining character outline has been omitted and the visual method has been relegated to an appendix. The computer-aided method is primarily used for reading printed material of print quality tolerance range

13、 Z, which has also been omitted from this British Standard as it is not used in the United Kingdom. The visual method was considered to lack the precision required for a reference procedure but it has been retained inAppendix D as it may be a convenient method to use as a rough check on print qualit

14、y for character sets OCRA and OCRB. ISO1831 also includes a requirement and test method for the assessment of variation in paper reflectance. This was not considered to be sufficiently important for inclusion in this BritishStandard as a requirement but for guidance the test method has been included

15、 inAppendix A. BS6616 also covers the use of the character set E13B for OCR. Although E13B is designed to be magnetically read there is an increasing trend for it to be optically read in which case the requirements of this standard apply. Fluorescence of paper can adversely affect the reading or sor

16、ting capabilities of some OCR systems and, as a consequence, this British Standard includes inAppendix A a recommendation for the maximum fluorescence to be exhibited by paper for OCR use. Currently there is no reference method for determining fluorescence, although the International Organization fo

17、r Standardization (ISO) hopes to prepare one. When this method is available it is envisaged that the recommended fluorescence limit inAppendix A will become a requirement of this British Standard to be verified using the ISO method of test. White paper is generally used where the technique of OCR is

18、 to be applied but the use of lightly tinted paper may be acceptable, provided the requirements of sections 2 and 3 are met. Print quality is critical to the machine recognition of characters and it is necessary for OCR characters to be of higher print quality than characters to be read by the unaid

19、ed human eye. Assessment of print quality includes the examination of the geometry of the character shape as well as the intensity of inking on the paper (print contrast). Ink of a high carbon black content is particularly suitable. The requirements of this standard apply to the printed image, not t

20、o the printing device (e.g.line printer) by which the printed image is produced. The character positioning requirements ensure that each OCR character is read by the reader without interference from other OCR characters or from non-OCR elements.BS6616:1986 BSI 07-1999 iii Reference is made in this s

21、tandard to the need for calibrated reference standards to be used for reflectance measurements. Within the United Kingdom ISO reference standards of level3 1) , which are issued by authorized laboratories, can be obtained from the Research Association for Paper and Board, Printing and Packaging Indu

22、stries (PIRA), Randalls Road, Leatherhead. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations

23、. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages1to 16, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on theinside

24、 front cover. 1) See measurement procedure described in BS4432-1.iv blankBS6616:1986 BSI 07-1999 1 Section 1. General 1 Scope This British Standard specifies requirements for the optical properties of paper to be used for optical character recognition (OCR), for print quality, including character sh

25、ape, quality, and positioning, and describes appropriate methods of test. The requirements are specifically for printed matter using one of the three character sets OCRA 2) , OCRB 2)and E13B 3)(the latter where optically read), although the requirements for paper quality, character quality and chara

26、cter positioning may be applied irrespective of the character set or font, the printing system, or the end use of the printed material. This specification does not include other dimensional requirements for the arrangement of characters. No specific dimensional measurements with respect to fields ar

27、e given in this standard. No measurement of the distance between the average horizontal centreline on a line of OCR characters and a top or bottom reference edge is defined since this is dependent on varying systems requirements. Colorimetric requirements are not specified, as they are considered un

28、necessary, other than by reference to the reflectance of the paper and the contrast between the paper and the print. The mechanical properties of the paper are not specified as the characteristics required will vary according to the reader being used; a list of appropriate standards is given in Sect

29、ional list SL22. NOTEThe titles of the publications referred to in this British Standard are given on the inside back cover. 2 Definitions For the purposes of this British Standard the following definitions apply. 2.1 Terms relating to paper quality 2.1.1 fluorescence F the portion of the reflectanc

30、e that can be directly attributed to the effect of a fluorescent whitening agent 2.1.2 gloss the property of a surface responsible for a lustrous or mirror-like appearance 2.1.3 opacity 4) the relationship, expressed as a percentage, between the reflectance factor R oand the intrinsic reflectance fa

31、ctor R Zof the same sheet of paper, obtained from the expression 2.1.4 Terms relating to reflectance 2.1.4.1 intrinsic reflectance factor R Z the reflectance factor of a sheet or pad of paper thick enough to be opaque 2.1.4.2 reflectance factor R 5) the relationship, expressed as a percentage, betwe

32、en the light reflected by a sheet of paper and that reflected by a perfect reflecting diffuser (i.e.having100% reflectance) under the same conditions 2.1.4.3 reflectance factor R o the reflectance factor R of a single sheet of paper with a black backing 2.1.5 Terms relating to sampling 6) NOTESeeFig

33、ure 1. 2.1.5.1 lot the aggregate of paper or board of a single kind, of special characteristics comprising one or more nominally identical units NOTEThe unit may be in the form of a reel, a bale, a bundle, the contents of a packing case, a pallet load, etc. Where the material to be tested has alread

34、y been incorporated into a manufactured article (for example a packing case), the lot is the aggregate of such articles of a single kind, of specified characteristics. 2.1.5.2 sample the aggregate of all the specimens 2.1.5.3 specimen a rectangle of paper or board cut to given dimensions, from the s

35、heet (or manufactured articles) taken from the selected units which form the lot 2) Described in BS5464. 3) Described in BS4810. 4) Definition based on 2.4 of BS4432-3:1980. 5) Definition based on2.1 and2.3 of BS4432-1:1975. 6) Definitions taken from BS3430. 100 R o R Z -BS6616:1986 2 BSI 07-1999 2.

36、2 Terms relating to print quality 2.2.1 best fit the position of a COL gauge over a character at which the character fills the minimum COL as much as possible and at the same time extends as little as possible beyond the maximum COL NOTESeeFigure 8 andAppendix C. 2.2.2 character outline limit (COL)

37、the outlines of a character. The minimum and maximum COL for a given character, in a specified font, character size and tolerance type, are the outlines of the printed image at the extremes of the tolerances for the strokewidth 2.2.3 character reflectance R p the reflectance factor of a point on a c

38、haracter 2.2.4 edge irregularity that part of the stroke edge extending either inside the minimum COL or outside the maximum COL 2.2.5 local reflectance R w the reflectance of the paper within the area of interest around a character NOTESeeC.1. 2.2.6 print contrast (PC), P the arithmetic difference

39、between the local reflectance R wof the paper and the character reflectance R p , i.e.R w R p 2.2.7 print contrast signal (PCS), P s The print contrast divided by the reflectance factor R oof the paper. 2.2.7.1 basic PCS values a set of PCS values obtained with a COL gauge in the best fit 2.2.7.2 co

40、ntrast variation ratio within a character (CVR), C the relationship between the means of the highest three and lowest three basic P svalues for a character 2.2.7.3 P sa the arithmetic mean of the highest80% of the basic P svalues 2.2.7.4 P smax the highest mean value of any three consecutive basic P

41、CS values for characters with a centreline2mm or more long or of five such consecutive values for characters with a centreline less than2mm long 2.2.7.5 P smin the lowest mean value of any three consecutive basic PCS values for characters with a centreline2mm or more long or of five such consecutive

42、 values for characters with a centreline less than2mm long 2.2.7.6 P s80% the lowest value of the upper80% of the basic P svalues 2.2.7.7 print contrast signal within a character the P svalue measured along the centreline of a character 2.2.8 spots any extraneous ink outside the maximum COL NOTESpot

43、s could be connected to or adjacent to the printed image, or could be free-standing within the clear area. Figure 1 Illustration of lot, sheet, specimenand sampleBS6616:1986 BSI 07-1999 3 2.2.9 stroke edge the line joining the points at which the reflectance is approximately halfway between that of

44、the local reflectance R wand the character reflectance R p 2.2.10 void an area inside the minimum COL that is significantly lighter than the rest of the character NOTESee7.2.3. 2.3 Terms relating to character positioning 2.3.1 character alignment within a line the vertical displacement of the lower

45、side of the character boundary, containing one character, relative to the lower side of the character boundary of another character within the same line boundary NOTE 1In the case of character sets OCRA and OCRB this displacement takes into account the intended position of the lowest edge, relative

46、to the baseline, of certain characters, e.g.lower case with descenders or symbols, when in their nominal positions. NOTE 2SeeFigure 6. 2.3.2 character boundary the smallest rectangle that has one side parallel to one of the document reference edges and which contains a character when aligned at the

47、stroke edge NOTESeeFigure 2. 2.3.3 character separation within a line the horizontal spacing between two adjacent vertical sides of the character boundaries of two characters within the same line boundary NOTESeeFigure 3. 2.3.4 character skew the rotational deviation, expressed in degrees, of the ve

48、rtical centreline of the character from the vertical document reference edge NOTESeeFigure 2. 2.3.5 character spacing within a line the horizontal distance between the vertical centrelines of the character boundaries of two characters within the same line boundary NOTESeeFigure 3. 2.3.6 clear area t

49、hat region of a document reserved for one line of characters and the space around those characters NOTESeeFigure 5. 2.3.7 document reference edge a specified horizontal and/or vertical edge of the document NOTESeeFigure 2. 2.3.8 external corner a corner where the angle defined by the strokes of the centreline is greater than180 NOTESeeFigure 12. 2.3.9 field a specific portion of a line, comprising at least one character NOTEA field may be treated as a unit of information. A line may comprise several fields. 2.3.10 intern