SIST EN 13619:2004
(Main)Postal services - Mail item processing - Optical characteristics for processing letters
Postal services - Mail item processing - Optical characteristics for processing letters
This document provides guidelines for printing addresses on mail items. These guidelines apply to addresses printed on mail items whose size is up to and including C5. It may also be applied to oversize items, commonly referred to as C5+. The address blocks covered are the addressee address block and the sender address block if they are both on the same side of the item. Otherwise, only the addressee address block is covered. Guidelines related to address lines are relevant for all lines in an address block.
Postalische Dienstleistungen - Bearbeitung von Sendungen - Optische Merkmale für die Briefbearbeitung
Diese Europäische Norm legt optische Merkmale für die Briefbearbeitung fest und enthält Leitlinien hinsichtlich der Werte dieser Attribute, die eine hohe Anschriftenlesbarkeit sicherstellen. Sie zielt darauf ab, die Beziehungen zwischen den Postbetreibern und ihren Kunden zu erleichtern, indem Informationen bereitgestellt werden, die die Versender verwenden können, um sicherzustellen, dass die von ihnen gedruckten Anschriften von postalischen Automatiksystemen erfolgreich bearbeitet werden können.
Es ist Ziel dieser Norm, folgende Punkte zu unterstützen:
Beurteilung der wahrscheinlichen Lesbarkeit einer gedruckten Anschrift mit vorgegebenen Erkennungsgeräten, ohne diese Geräte tatsächlich einzusetzen;
Festlegung von Änderungen bei den Anschriftendruckmerkmalen, die erforderlich sind, um beim Einsatz vorgegebener Anschriftenlesegeräte den gewünschten Grad der Anschriftenlesbarkeit zu erreichen;
Beurteilung der Komplexität und somit auch der Kosten von Anschriftenlesegeräten, die für die gewünschte Anschriftenlesbarkeit mit vorgegebenen Druckmerkmalen erforderlich sind.
Die Norm gilt für Postsendungen einer Größe bis zu C5 ); sie kann aber auch auf übergroße Sendungen mit der gebräuchlichen Bezeichnung C5+ angewandt werden sowie auf Langbriefe. Die betroffenen Anschriftenblöcke sind:
der Empfängeranschriftenblock;
der Absenderanschriftenblock, wenn dieser sich auf derselben Seite der Postsendung befindet wie der Empfängeranschriftenblock.
Die in dieser Norm enthaltenen Leitlinien gelten für Anschriftenblöcke, so wie sie auf den fertigen Postsendungen erscheinen, wenn diese an die Postbetreiber übermittelt werden, und nicht nur für Anschriften und das Trägermaterial, auf dem sie gedruckt sind. Anwender dieser Norm sind verantwortlich für die Festlegung der physikalischen Parameter, die für die Einhaltung erforderlich sind, nachdem die Eigenschaften der Postsendungen berücksichtigt wurden, die nichts mit dem Aufdruck selbst zu tun haben, wie z. B. die
Services postaux - Traitement des objets postaux - Caractéristiques optiques pour le traitement du courrier
La présente norme européenne détermine un ensemble de caractéristiques optiques pour le traitement du courrier et fournit des recommandations sur les valeurs de ces attributs pour assurer un niveau élevé de lisibilité des adresses. L'objectif est de faciliter les relations entre les opérateurs postaux et les clients en donnant des informations que les fabricants de courrier peuvent utiliser pour que les adresses qu'ils impriment puissent etre lues correctement par les systemes postaux de lecture automatique.
Cette norme est destinée a contribuer a :
l'évaluation de la lisibilité probable d'une adresse imprimée au moyen d'un systeme de reconnaissance donné, sans avoir a la soumettre effectivement a un systeme de ce type ;
la détermination des modifications des caractéristiques d'impression des adresses, nécessaires pour parvenir au niveau de lisibilité voulu pour un systeme de reconnaissance d'adresses donné ;
l'évaluation de la complexité et donc du cout, des systemes de reconnaissance d'adresses nécessaires pour parvenir a un niveau de lisibilité voulu avec des adresses ayant des caractéristiques d'impression données.
Cette norme s'applique aux objets dont le format va jusqu'au C5 ) et aussi pour les objets de grandes dimensions, communément désignés comme le C5+, et les objets plats. Les blocs adresses concernés sont :
le bloc adresse de distribution ;
le bloc adresse de l'expéditeur s'il figure sur la meme face de l'objet que le bloc adresse de distribution.
Les recommandations portent sur les blocs adresses tels qu'ils apparaissent sur les objets postaux achevés remis aux opérateurs postaux, et non pas seulement sur les adresses avec le support ou ils sont imprimés. Il est de la responsabilité des utilisateurs de la norme de déterminer les parametres physiques nécessaires pour respecter les recommandations apres avoir pris en compte les caractéristiques résultant d'opérations autres que l'impression, telles que la mise sous pli, l'utilisation d
Poštne storitve - Prenos pošiljk - Optične karakteristike za prenos pisemskih pošiljk
General Information
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Postal services - Mail item processing - Optical characteristics for processing lettersSRãLOMNServices postaux - Traitement des objets postaux - Caractéristiques optiques pour le traitement du courrierPostalische Dienstleistungen - Bearbeitung von Sendungen - Optische Merkmale für die BriefbearbeitungTa slovenski standard je istoveten z:EN 13619:2002SIST EN 13619:2004en03.240Poštne storitvePostal servicesICS:SLOVENSKI
STANDARDSIST EN 13619:200401-september-2004
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 13619November 2002ICS 03.240English versionPostal services - Mail item processing - Optical characteristicsfor processing lettersServices postaux - Traitement des objets postaux -Caractéristiques optiques pour le traitement du courrierPostalische Dienstleistungen - Bearbeitung von Sendungen- Optische Merkmale für die BriefbearbeitungThis European Standard was approved by CEN on 16 October 2002.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Management Centre or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2002 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 13619:2002 E
EN 13619:2002 (E)2ContentsForeword.31Scope.52Terms and definitions.63Symbols and abbreviations.154Guidelines.154.1Address zone background attributes.154.1.1Background colour.154.1.2Background noise.164.2Address block attributes.164.2.1Address block size.164.2.2Clear zone.164.2.3Address block skew.164.2.4Line spacing.174.2.5Bar codes.174.2.6Characters per line.174.3Character attributes.174.3.1Fonts.174.3.2Stroke thickness.184.3.3Type size.184.3.4Character spacing.184.3.5Word spacing.184.3.6Character sets.194.3.7Colour.194.3.8Underlining.194.3.9Print quality.194.3.10Print contrast ratio (PCR) of address characters vs. background.195Salience of attributes.195.1General.195.2Address zone background attributes.205.3Address block attributes.205.4Character attributes.21Bibliography.22
EN 13619:2002 (E)3ForewordThis document EN 13619:2002 has been prepared by Technical Committee CEN/TC 331, "Postal services" thesecretariat of which is held by NEN.This European Standard shall be given the status of a national standard, either by publication of an identical text orby endorsement, at the latest by May 2003, and conflicting national standards shall be withdrawn at the latest byMay 2003.This document has been prepared under a mandate given to CEN by the European Commission and the EuropeanFree Trade Association, and supports essential requirements of EU Directive(s).This European Standard contains a bibliography.According to the CEN/CENELEC Internal Regulations, the national standards organizations of the followingcountries are bound to implement this European Standard : Austria, Belgium, Czech Republic, Denmark, Finland,France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain,Sweden, Switzerland and the United Kingdom.
EN 13619:2002 (E)4IntroductionRapidity of mail processing and delivery is the most important feature of Quality of Service which is requested byany Customer of a Postal Operator.Mail processing is highly dependent upon the level of automation achieved in the mail sorting process. Suchautomation depends on the speed and accuracy of interpretation of mail item addresses by optical characterrecognition (OCR) equipment and/ or human operators (video-coders) working from video images of the mail items.The purpose of this standard is to assist mailers to maximise the OCR readability of their mail items by providingguidelines for printing postal addresses. Some of the guidelines also support video encoding from grey levelpictures.The guidelines are necessarily derived from a view of the current state-of-the-art in the application of OCR andimage processing technology to address reading. Such a state-of-the-art is not a perfectly defined concept. First, itis likely to evolve with time, resulting in improved recognition capability. Second, the performance of an OCRsystem is always the result of a compromise between recognition capability and cost. This is why the standard isexpressed in the form of guidelines rather than prescriptions.Compliance with the guidelines should assure a high level of address readability with currently availabletechnology. However, the guidelines should not be interpreted as strict, mandatory, all-or-nothing rules. Rather, thedegree of compliance with them can be expected to influence the level of address readability: the higher the degreeof compliance, the higher the likely level of address readability.The guidelines are based on address attributes that tend to influence address readability. To the extent that this ispossible, these attributes have been selected so as to be easily controllable by mailers and to be measurable usingsimple, low-cost, means. This is the reason why the standard is largely built on common notions of typography andmakes use of colour reference systems that are likely to be known by mailers.It is not technically possible to define guidelines concerning solely the printing of addresses without taking intoaccount the production of the mail item as a whole. For example, print contrast is not only dependent on theink/paper combination. It also results from a variety of other factors, including the covering of the mail item and thematerial of the transparent window through which the address is read. The guidelines provided in the standardtherefore apply to the address zones of finished mail items and not just to the address and the substrate on which itis printed.
EN 13619:2002 (E)51 ScopeThis European Standard specifies optical characteristics for processing letters and gives guidelines on the valuesof these attributes that will assure a high level of address readability. It is aimed at facilitating relations betweenPostal Operators and Customers by providing information that mailers can use to ensure that the addresses theyprint can be processed successfully by postal automation systems.The standard is intended to support:¾ assessment of the probable readability of a printed address, using given address recognition equipment,without actually submitting it to the equipment;¾ determination of the changes in address printing characteristics that are required to achieve a desired level ofaddress readability using given address recognition equipment;¾ assessment of the complexity, and thus the cost, of the address recognition equipment needed to achieve adesired level of readability of addresses with given printing characteristics.The standard applies to mail items whose size is up to and including C51, but may also be applied to oversizeitems, commonly referred to as C5+, and to flats. The address blocks covered are:¾ the delivery address block;¾ the sender address block if this is printed on the same side of the mail item as the delivery address block.The guidelines provided in the standard apply to address blocks as they appear on finished mail items whensubmitted to postal operators, and not just to addresses and the substrate on which they are printed. Users of thestandard are responsible for determining the physical parameters which are required to achieve compliance aftertaking account of characteristics which result from mail item features, other than printing, such as covering, the useof transparent window envelopes and the use of address labels.The guidelines are based on physical attributes that tend to influence the readability of addresses by opticalcharacter recognition (OCR) equipment and by video-coders. To the extent that this is possible, attributes havebeen selected so as to be easily controllable and to be measurable using simple, low-cost, means. The attributevalues given are based on common notions of typography and on colour reference systems that are likely to beknown by mailers. The values given should be interpreted as recommendations or guidelines, not as strict,mandatory, all-or-nothing rules.OCR systems are complex and their behaviour is therefore not easily modelled by simple attributes. As a result theambition of the standard is limited by the difficulty of defining some attributes in formal terms, even though theirinfluence on address readability has been proven. Where this is the case, the standard uses examples, lists ofpreferred values, or literal descriptions to give hints on how to maximise address readability.Since all attributes do not contribute uniformly to the readability of an address, the standard identifies two levels ofsalience for each attribute (high and normal). These two levels are designed to aid in the definition of readabilityclasses by users of the standard.This standard considers a printed address as being made up of a series of lines of printed information2. Guidelinesrelated to such address lines are relevant for all lines in an address block.
1 See ISO 2692 Note that this standard does not define the logical content, in terms of address components, of each line. Nor does it directly impose limits onthe length of individual lines or components, or on how information is represented (e.g. as text and/or in computer readable bar codes). AddressComponents are covered in CEN/TC 331 WI 015 Part I; the selection and ordering of components for printing and the abbreviation rules whichmay be used to limit printed address line length, are to be addressed in Part II of that standard.
EN 13619:2002 (E)62 Terms and definitionsFor the purposes of this European Standard, the following terms and definitions apply. In addition, relevantdefinitions may be found in the documents listed in the Bibliography.2.1address blockthe minimum rectangle encompassing the address lines2.2address zonelargest rectangle, with sides which are parallel and perpendicular to the reference edge of a mail item, whichencloses the minimal rectangle but does not include characters, or markings which may be interpreted ascharacters, other than those in the minimal rectangle itself. When present, the borders of transparent envelopewindows limit the extent of the address zoneNOTE 1See Figure 1.NOTE 2When present, the borders of transparent windows limit the extent of the address zone because dark shadows mayappear on OCR images due to the relief existing at those borders. Label edges may have a similar effect.Figure 1 — Definition of the address zone, clear zone and minimal rectangle2.3alignline up typeset or other graphic material in accordance with relevant specifications, using a base or vertical line asreference2.4ascenderpart of certain lowercase letters that extends above the x-height of a fontNOTEExamples of such lower case letters are b and f. See Figure 2.
EN 13619:2002 (E)7Figure 2 — Reference lines and dimensions2.5ascender linesee cap lineNOTESee Figure 2.2.6base lineline along which the bases of all capital letters (and most lowercase letters) are positionedNOTESee Figure 2.2.7bar codelinear array of rectangular marks of (possibly) varying width, height and vertical alignment, separated by spaces of(possibly) varying width, in which the positioning and size of marks and spaces are used to encode information2.8binarizationprocess by which a grey-scale digital image is converted into a binary imageNOTEThis process may involve complex computations.2.9binary imagedigital image formed by pixels of binary (0 or 1) valueNOTE1 is usually interpreted as black and 0 as white.2.10body sizeheight of the type measured from the top of the tallest ascender to the bottom of the lowest descenderNOTEBody size is normally given in points (pt).2.11bold typetype with a heavier darker appearanceEXAMPLEThis is in bold; this is in normal font.2.12capcommonly used abbreviation for “capital letter”EXAMPLEM is a capital letter or cap; m is the corresponding lower case letter.
EN 13619:2002 (E)82.13cap heightthe height of the uppercase letters within a fontNOTESee Figure 2.2.14cap lineline touching the tops of uppercase letters within a fontNOTESee Figure 2.2.15character skewextent to which individual characters are skewed relative to the base line2.16character spacewidth of the vertical white zone between two successive charactersNOTEThe space between characters may vary within and between fonts in many complex ways. The definition of characterspace used in this document is the width of the vertical space between two successive characters. There may thus be nocharacter space, for example if characters are skewed or for some italic fonts.2.17clear zonearea of the address zone which falls outside of the minimum rectangleNOTESee Figure 1.2.18condensed, condensed typetype that is narrow in width proportionate to its heightEXAMPLEThis is an example of condensed type. This is an example of normal (not condensed) type.2.19contrastrange of tones in a photograph ranging from highlight to shadow2.20dashshort horizontal line used for punctuation2.21descenderpart of certain lowercase letters that extends below the base line of the letterNOTEExamples of lowercase letters that have descenders are y and q. See Figure 2.2.22digital imagearray of computerised numbers representing the image of an object or a scene2.23dot matrix charactercharacter printing in which each character is formed from a matrix of separate or overlapping equally sized dots
EN 13619:2002 (E)92.24dots per inch, dpimeasurement of resolution for page printers, phototypesetting machines, digital images, and graphics screensNOTEAn inch is approximately equivalent to 25,4 mm. Thus, for example, 200 dpi is approximately equal to 8 (200/25.4) dotsper millimetre.2.25embossing(1) relief images formed by using a recessed die(2) using a recessed die to form a relief image2.26expanded typetypeface with a slightly wider body giving a flatter appearance2.27extended typesee expanded type2.28facesee typeface2.29fixed spacingmethod of spacing whereby each character has the same pitch2.30flushaligned to the margin, i.e., with no indention2.31flush left, left justifiedaligned along the left margin2.32fonta complete set of characters for one typeface at one particular type sizeNOTEFont is often used more loosely as a synonym for typeface.2.33grey-level, grey-scalerange of luminance values for evaluating shading from white to blackNOTEGrey-scale is a term frequently used in discussions about scanners as a measure of their ability to capture halftoneimages.2.34grey-scale imagedigital image where each pixel receives a value interpreted as a local luminanceNOTETypical grey scale images have pixels with 256 possible luminance values. In binary format this range of values can berepresented by 8 bits of information.2.35halftoneimage formed from a pattern of dots of varying size
EN 13619:2002 (E)10NOTELight areas have small dots and darker areas or shadows have larger dots.2.36Helveticaname of a particular sans serif typeface2.37inchlinear unit of measurement commonly used with reference to printing and image resolution.NOTEOne inch is approximately equal to 25,4 mm.2.38italicvariety of typeface slanting to the right in relation to the baselineNOTEItalic is often used to attract attention. This is in italic.2.39justifyalign the beginning and / or end of lines in a block of text in such a way that each line starts (and / or ends) at thesame distance from a line drawn perpendicular to the base line of one line of the textNOTEIn left justification, the beginnings of the lines are aligned; in right justification, the ends of the lines are aligned. Fulljustification, in which both ends are aligned, is achieved by adjusting the spacing between the words and characters.2.40lead, leadingspace added between lines of type to space out text and provide visual separation of the linesNOTELead (leading) is measured in points (pt) or fractions thereof.2.41left justifiedsee flush left2.42ligatureletters which are joined together as a single unit of typeEXAMPLEŒ and Æ.2.43line skewmisalignment or slant of a line of printed characters with respect to the reference edge (normally the bottom) of theobject or surface on which the printing appears
EN 13619:2002 (E)112.44line spacinggap between the base line of one line of text and the ascender line of the next. It is measured in points (pt).NOTESee Figure 3.Figure 3 — Measuring line spacing2.45logo, logotype(1) a word, a combination of letters or a picture, set as a single unit(2) specially styled company name and / or symbol designed as part of a corporate image2.46lower casethe small letters in a font2.47minimal rectanglesmallest rectangle that encloses all characters in a printed address and which has sides which are parallel andperpendicular to the reference edge (normally the bottom) of the mail itemNOTESee Figure 1.2.48multi-line optical character reader (MLOCR)machine that automatically reads several lines of the address block on mail2.49OCR fontscharacter fonts designed so as to be easily recognised by optical character recognition systemsNOTEThere exist two OCR fonts: OCR-A and OCR-B.2.50opacitymeasure of a material’s capacity to block the passage of lightNOTEThe degree of opacity is described in terms of a contrast ratio which has two types: opacity (89 % reflectance backing)and opacity (paper backing).(See ISO 2471:1998).2.51optical character recognition, OCRtechnique by which characters contained in digital images can be machine identified
EN 13619:2002 (E)122.52pitch (character)number of characters per distance unit measured horizontallyNOTEFixed spacing fonts have the same pitch for every character; proportional spacing fonts have a pitch that varies fromcharacter to character.2.53pixel (picture element)the basic element in a digital image2.54point, ptunit of measurement, often used to measure type sizeNOTEThe point is 1/72 of an inch, or approx. 0,35 mm.2.55point sizenumber of points measured between the ascender line and the descender line2.56Print Contrast Ratio, PCRa measurement of the print contrast that is, in mathematical notation:PCR = 100 % · (Rb-Rp) / RbwhereRbis the reflectance of the background; andRpis the reflectance of the ink.NOTEThe method of PCR measurement is defined in ISO 1831.2.57print contrast signal, PCSsee print contrast ratio2.58proportional spacingmethod of spacing whereby each character is spaced to accommodate the varying widths of letters or figures,resulting in text that has a visually pleasing appearance2.59reflectance (R) a measure of the ability to reflect light of a given wavelengthNOTEThe reflectance measures the percentage of incident light diffusely reflected by the material in question. Only diffuse(scattered) reflectance is of interest. A surface that perfectly reflects the incident light has a reflectance of 100 %. A surfacereflecting only half of the incident light has a reflectance of 50 %. (see ISO 2469:1994).2.60reflectionprocess by which radiation is returned from a surface or medium without a change in frequency (i.e. with nofluorescence)NOTEPart of the radiation falling on a medium is reflected at the surface of the medium (surface reflection); another part maybe scattered back from the interior of the medium, whilst part may be absorbed or passed through the material.
EN 13619:2002 (E)132.61regular reflection, specular reflectionprocess by which incident light is reflected by an object's surface without diffusion2.62resolution(regarding image) number of pixels per distance unit in a digital image(regarding print) measurement used in digital printing to express quality of outputNOTE 1Image resolution is measured in pixels per mm (pixels/mm) or in dots per inch (dpi). The greater the resolution, thefiner the detail which may be extracted from the image but the greater the amount of memory needed to store it. The camerason OCR systems typically capture images with a resolution of approx. 8 pixels/mm.NOTE 2Print resolution is measured in dots per inch (dpi). The greater the resolution, the smoother and cleaner the printing willappear. Currently most Page (laser) Printers print at 300, 400 or 600 dpi. Typesetting machines print at 1200 dpi or more.2.63Romantype which has vertical stemsNOTE 1Roman is distinct from italics or oblique which are set at angles.NOTE 2The term Roman is sometimes used as a synonym for serif type.2.64sans-serif typetypeface that has no serifsNOTEHelvetica, Optima, and Futura are examples of sans-serif typefaces.2.65scannerdigitising device using light sensitivity to translate a picture or typed text into a digital image which can beprocessed and stored by a computer2.66scatteringprocess by which the spatial distribution of a beam of radiation is changed when it is reflected in many directions bya surface or medium without changing the frequency of its monochromatic components2.67security background, security paperpaper incorporating special features designed to increase security and prevent forgeryNOTEExamples of security features include dyes and watermarks. Security paper is used e.g. for cheques and bank notes.2.68serifa small cross stroke accentuating the ends of the main strokes of characters in some typefacesNOTESee Figure 4.
EN 13619:2002 (E)14Figure 4 — Comparison of serif and sans serif fonts2.69serif typetypeface that has serifsNOTE 1Times, Baskerville and Courier are examples of serif typefaces.NOTE 2Also called "Roman," although "Roman" is also used to describe type that is neither italic nor bold.2.70show-throughthe extent to which printing on one side of a material can be seen from the other side, or through another layer(sheet) of the materialNOTESee also opacity; highly opaque materials do not suffer from show-through.2.71skewsee character skew and line skew2.72specular reflectionsee regular reflection2.73strokeline or lines that form each character2.74typeface, facea complete set of characters forming a family in a particular design or styleNOTEcf font.2.75type sizesize of type, measured in points between the bottom of the descender and the top of the ascenderNOTESee Figure 2.2.76underliningpractice of emphasising printed text by printing a horizontal line just below the baselineEXAMPLEThis text is underlined; this text is not.
EN 13619:2002 (E)152.77x-heightheight of a letter excluding the ascenders and descenders if anyNOTESee Figure 2.3 Symbols and abbreviationsFor the purposes of this European Standard, the following symbols and abbreviations apply.B530(green) portion of the spectrum defined in ISO 1831B680(red) portion of the spectrum defined in ISO 1831dpidots per inchMLOCRmulti-line optical character readerOCRoptical character recognitionPCRprint contrast ratioPCSprint contrast signalptpointRreflectanceRbbackground reflectanceRpink (print) reflectance4 GuidelinesThe following clauses identify physical attributes that influence the readability of addresses printed on mail itemsand provide guidelines on the values of these attributes that will assure a high level of address readability. Theattributes are organised into three groups:¾ background attributes;¾ address block attributes;¾ character attributes.4.1 Address zone background attributesThe following recommendations apply throughout the address zone.4.1.1 Background colourBackground reflectance should be in excess of 50 % in both red (B680) and green (B530) portions of the spectrum.The gloss (specular reflection) of the address zone should be kept to a minimum.NOTE 1When the address is read through a transparent window, reflectance should be measured through the window.NOTE 2OCR systems usually operate from binary images where characters should appear in black and background in white.The contrast between characters and background is generally measured on a local basis. Therefore, regular or specular
EN 13619:2002 (E)16reflection may also be an impediment (e.g. when transparent windows are used) for particular configurations of light sourcesand sensors. This is why the gloss of the address zone should be kept to a minimum.Background colour is indirectly constrained by recommendations on PCR (see 4.3.10); white background ispreferred. Pastels and light colours are also acceptable provided that these constraints are met.NOTE 3Background colour should be light enough to appear as white after binarization.4.1.2 Background noiseAny pattern from inside the envelope or show-through of the reverse (inner) side of the envelope should have aprint contrast ratio less than 15 %, measured in both red (B680) and green (B530) portions of the spectrum.Halftones should have a print resolution of 16 or more points per millimetre.NOTE 1Interference may occur
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