Unit5Barcode[77]

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Barcode[86]

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How2DBarCodeswillWork?[94]參考譯文條形碼

Abarcodeisanopticalmachine-readablerepresentationofdata,whichshowsdataabouttheobjecttowhichitattaches.Originallybarcodesrepresenteddatabyvaryingthewidthsandspacingsofparallellines,andmaybereferredtoaslinearor1Dimensional(1D).Latertheyevolvedintorectangles,dots,hexagonsandothergeometricpatternsin2Dimensions(2D).BarcodeTextAAlthough2Dsystemsuseavarietyofsymbols,theyaregenerallyreferredtoasbarcodesaswell.Barcodesoriginallywerescannedbyspecialopticalscannerscalledbarcodereaders;later,scannersandinterpretivesoftwarebecameavailableondevicesincludingdesktopprintersandsmartphones.Figure5.1AUPC-Abarcodesymbol

Thefirstuseofbarcodeswastolabelrailroadcars,buttheywerenotcommerciallysuccessfuluntiltheywereusedtoautomatesupermarketcheckoutsystems,ataskforwhichtheyhavebecomealmostuniversal(SeeFigure5.1).TheirusehasspreadtomanyothertasksthataregenericallyreferredtoasAutomaticIdentificationandDataCapture(AIDC).TheveryfirstscanningofthenowubiquitousUniversalProductCode(UPC)barcodewasonapackofWrigleyCompanychewingguminJune1974.

OthersystemshavemadeinroadsintheAIDCmarket,butthesimplicity,universalityandlowcostofbarcodeshaslimitedtheroleoftheseothersystemsuntilthefirstdecadeofthe21stcentury,over40yearsaftertheintroductionofthecommercialbarcode,cametheintroductionoftechnologiessuchasRadioFrequencyIDentification(RFID).

1.Use

BarcodessuchastheUPChavebecomeaubiquitouselementofmoderncivilization,asevidencedbytheirenthusiasticadoptionbystoresaroundtheworld;almosteveryitemotherthanfreshproducefromagrocerystore,departmentstore,andmassmerchandiserhasaUPCbarcodeonit.Thishelpstrackitemsandalsoreducesinstancesofshopliftinginvolvingpricetagswapping,althoughshoplifterscannowprinttheirownbarcodes.Inaddition,retailchainmembershipcards(issuedmostlybygrocerystoresandspecialty"bigbox"retailstoressuchassportingequipment,officesupply,orpetstores)usebarcodestouniquelyidentifyconsumers,allowingforcustomizedmarketingandgreaterunderstandingofindividualconsumershoppingpatterns.Atthepointofsale,shopperscangetproductdiscountsorspecialmarketingoffersthroughtheaddressorE-mailaddressprovidedatregistration.

Barcodescanallowfortheorganizationoflargeamountsofdata.Theyarewidelyusedinthehealthcareandhospitalsettings,rangingfrompatientidentification(toaccesspatientdata,includingmedicalhistory,drugallergies,etc.)tomedicationmanagement.Theyarealsousedtofacilitatetheseparationandindexingofdocumentsthathavebeenimagedinbatchscanningapplications,tracktheorganizationofspeciesinbiology,andintegratewithin-motioncheckweigherstoidentifytheitembeingweighedinaconveyorlinefordatacollection.

Theycanalsobeusedtokeeptrackofobjectsandpeople;theyareusedtokeeptrackofrentalcars,airlineluggage,nuclearwaste,registeredmail,expressmailandparcels.Barcodedticketsallowtheholdertoentersportsarenas,cinemas,theatres,fairgrounds,andtransportation,andareusedtorecordthearrivalanddepartureofvehiclesfromrentalfacilitiesetc.Thiscanallowproprietorstoidentifyduplicateorfraudulentticketsmoreeasily.Barcodesarewidelyusedinshopfloorcontrolapplicationssoftwarewhereemployeescanscanworkordersandtrackthetimespentonajob.

Some2Dbarcodesembedahyperlinktoawebpage.Acapablecellphonemightbeusedtoreadthepatternandbrowsethelinkedwebsite,whichcanhelpashopperfindthebestpriceforaniteminthevicinity.Since2005,airlinesuseanIATA-standard2Dbarcodeonboardingpasses,andsince20082Dbarcodessenttomobilephonesenableelectronicboardingpasses.

2.Symbologies

Themappingbetweenmessagesandbarcodesiscalledasymbology.Thespecificationofa

symbologyincludestheencodingofthesingledigits/charactersofthemessageaswellasthestartandstopmarkersintobarsandspace,thesizeofthequietzonerequiredtobebeforeandafterthebarcodeaswellasthecomputationofachecksum.

Linearsymbologiescanbeclassifiedmainlybytwoproperties:

·Continuousvs.discrete:charactersincontinuoussymbologiesusuallyabut,withonecharacterendingwithaspaceandthenextbeginningwithabar,orviceversa.Charactersindiscretesymbologiesbeginandendwithbars;theintercharacterspaceisignored,aslongasitisnotwideenoughtolooklikethecodeends.

·Two-widthvs.many-width:barsandspacesintwo-widthsymbologiesarewideornarrow;theexactwidthofawidebarhasnosignificanceaslongasthesymbologyrequirementsforwidebarsareadheredto(usuallytwotothreetimeswiderthananarrowbar).Barsandspacesinmany-widthsymbologiesareallmultiplesofabasicwidthcalledthemodule;mostsuchcodesusefourwidthsof1,2,3and4modules.

Somesymbologiesuseinterleaving.Thefirstcharacterisencodedusingblackbarsofvaryingwidth.Thesecondcharacteristhenencodedbyvaryingthewidthofthewhitespacesbetweenthesebars.Thuscharactersareencodedinpairsoverthesamesectionofthebarcode.

Themostcommonamongthemany2Dsymbologiesarematrixcodes,whichfeaturesquareordot-shapedmodulesarrangedonagridpattern.2Dsymbologiesalsocomeincircularandotherpatternsandmayemploysteganography,hidingmoduleswithinanimage.

Linearsymbologiesareoptimizedforlaserscanners,whichsweepalightbeamacrossthebarcodeinastraightline,readingasliceofthebarcodelight-darkpatterns.Stackedsymbologiesarealsooptimizedforlaserscanning,withthelasermakingmultiplepassesacrossthebarcode.

Inthe1990sdevelopmentofChargeCoupledDevice(CCD)imagerstoreadbarcodeswaspioneeredbyWelchAllyn.Imagingdoesnotrequiremovingparts,asalaserscannerdoes.In2007,linearimaginghadbeguntosupplantlaserscanningasthepreferredscanengineforitsperformanceanddurability.

2Dsymbologiescannotbereadbyalaserasthereistypicallynosweeppatternthatcanencompasstheentiresymbol.Theymustbescannedbyanimage-basedscanneremployingaCCDorotherdigitalcamerasensortechnology.

3.Scanners(barcodereaders)

Theearliest,andstillthecheapest,barcodescannersarebuiltfromafixedlightandasinglephotosensorthatismanually"scrubbed"acrossthebarcode.

Barcodescannerscanbeclassifiedintothreecategoriesbasedontheirconnectiontothecomputer.TheoldertypeistheRS-232barcodescanner.Thistyperequiresspecialprogramming

fortransferringtheinputdatatotheapplicationprogram.

"Keyboardinterfacescanners"connecttoacomputerusingaPS/2orATkeyboard-compatibleadaptorcable.Thebarcode'sdataissenttothecomputerasifithadbeentypedonthekeyboard.

Likethekeyboardinterfacescanner,USBscannersareeasytoinstallanddonotneedcustomcodefortransferringinputdatatotheapplicationprogram.

4.Benefits

Inpoint-of-salemanagement,barcodesystemscanprovidedetailedup-to-dateinformationonthebusiness,acceleratingdecisionsandwithmoreconfidence.Forexample:

·Fast-sellingitemscanbeidentifiedquicklyandautomaticallyreordered.

·Slow-sellingitemscanbeidentified,preventinginventorybuild-up.

·Theeffectsofmerchandisingchangescanbemonitored,allowingfast-moving,moreprofitableitemstooccupythebestspace.

·Historicaldatacanbeusedtopredictseasonalfluctuationsveryaccurately.

·Itemsmayberepricedontheshelftoreflectbothsalepricesandpriceincreases.

·Thistechnologyalsoenablestheprofilingofindividualconsumers,typicallythroughavoluntaryregistrationofdiscountcards.Whilepitchedasabenefittotheconsumer,thispracticeisconsideredtobepotentiallydangerousbyprivacyadvocates.

Besidessalesandinventorytracking,barcodesareveryusefulinlogistics.

·Whenamanufacturerpacksaboxforshipment,aUniqueIdentifyingNumber(UID)canbeassignedtothebox.

·AdatabasecanlinktheUIDtorelevantinformationaboutthebox;suchasordernumber,itemspacked,quantitypacked,destination,etc.

·TheinformationcanbetransmittedthroughacommunicationsystemsuchasElectronicDataInterchange(EDI)sotheretailerhastheinformationaboutashipmentbeforeitarrives.

·ShipmentsthataresenttoaDistributionCenter(DC)aretrackedbeforeforwarding.Whentheshipmentreachesitsfinaldestination,theUIDgetsscanned,sothestoreknowstheshipment'ssource,contents,andcost.

Barcodescannersarerelativelylowcostandextremelyaccuratecomparedtokey-entry,withonlyabout1substitutionerrorin15,000to36trillioncharactersentered.Theexacterrorratedependsonthetypeofbarcode.

1.IntroductiontoHow2DBarCodesWork

Inthesummerof1974atagrocerystoreinTroy,Ohio,aneventfirsttookplacethatwouldforeverchangethewaywepurchasethings:AclerkscannedtheUPCcodeonapackofWrigley'sgum.How2DBarCodeswillWork?TextBUPCcodesexplodedinpopularityafterhittingthemarket,andtodayyoucanfindthemonpracticallyeveryproductontheshelves.Likeallbarcodes,UPCcodesbridgedthephysicalanddigitalworlds,providinganyonewithabarcodescannerinstantaneousaccesstothedatathatabarcodecontains.

Likeallofthefirstbarcodeformats,UPCcodeswere1D,meaningtheyonlycarriedinformationinonedirection.One-dimensionalcodesworkedfineforcarryingsmallamountsofdatalikenumericproductcodes,butasthedigitalworldbecamemorecomplex,theneedforabarcodecapableofcarryingmoredatabecameapparent.

Onesolutionstillusedtodayisthestackedbarcode,which,asthenameimplies,containsanumberof1Dcodespiledoneontopofanother.Althoughstackedbarcodescanaccommodatemoreinformationthantheirtraditional1Dcounterparts,theycanquicklygrowverylargeinordertostoremoredataandcanbedifficulttoread.Inordertohaveabarcodethatwassmallinsize,easytoreadandcapableofholdingbothalargeamountofdataandalargevarietyofcharactertypes,themarketcalledforanewapproach.Enter2Dbarcodes.(SeeFigure5.2)

2Dbarcodescanholdmountainsofinformation,

comparedtotheirlow-tech1Dpredecessors.

Figure5.22Dbarcodes

Asyoumighthaveguessed,2Dbarcodes(sometimescalledmatrixcodes)carryinformationintwodirections:verticallyandhorizontally.Accordingly,2Dbarcodesarecapableofholdingtensandevenhundredsoftimesasmuchinformationas1Dbarcodes.Forinstance,oneofthemostpopular2Dbarcodeformats,DensoWave'sQRCode,canholdmorethan7,000digitsor4,000charactersoftext,whereaseventhemostcomplex1Dcodestopoutaround20characters.2Dbarcodesarealsosmallandeasytoscan.

Still,2Dcodesaren'tperfectforeveryapplication.Becausethey'remorecomplexthan1Dcodes,theyrequiremorepowerfulscannerstodecode.What'smore,manypeoplearesimplyunfamiliarwiththetechnology,whichhinderswidespreadadoption.Butthankstothesmartphoneinyourpocket,thatmayallbeabouttochange.Readontofindoutwhy.

2.2DBarCodeGeneratorsandScanners

WhenthenowubiquitousUPCcodefirststartedmakingwavesinthe1970s,retailerseverywhererecognizedthepotentialimmediately.Unfortunately,thetechnologyfacedsomethingofaCatch-22.RetailersrefusedtobuytheexpensivescannersneededtoreadthecodesuntilmanufacturersbeganputtingUPCcodesonalloftheirproducts,andmanufacturersstonewalledonadoptingthemuntiltheyknewretailerscouldreadthecodes.Eventually,largeretailerslikeKmartjumpedintokick-startthetechnology.

Fortunatelyforproponentsof2Dbarcodes,webuymillionsofscannerseveryyearintheformofoursmartphones.CommonmodelsliketheiPhone,BlackBerryandAndroidallhavethecapabilitytoreadthemostpopular2Dbarcodeformats,helpingtoclearperhapsthelargesthurdletotheirwidespreadadoption.Buthowdoesasmartphone—oranybarcodescanner,forthatmatter—actuallymakesenseoftheseeminglyunintelligiblepatternsoflinesandsquaresthat2Dbarcodescontain?Partoftheanswerliesinthedesignofthebarcodeitself,whichiscreatedfromthegrounduptomakethescanningprocessasaccurateandspeedyaspossible.

Let'scheckoutofoneofthemostwidespreadtypesof2Dbarcodes,QRCodes,toseehowitsdesignhelpsbarcodescannersreadthedataitcontains.Forstarters,everyQRCodecontainsafinderpattern,anarrangementofsquaresthathelpthescannerdetectthesizeoftheQRCode,thedirectionit'sfacingandeventheangleatwhichthecodeisbeingscanned.Next,everyQRCodecontainsanalignmentpattern,anotherpatternofsquaresdevisedtohelpscannersdetermineifthe2Dbarcodeisdistorted(perhapsit'splacedonaroundsurface,forinstance).QRCodesalsohavemarginsforerror,meaningthatevenifpartofthecodeissmudgedorobscured,thecodecanoftenstillbescanned.

Butevenaperfectlydesignedbarcodewouldbenothingwithoutsophisticatedsoftwarecapableofrecognizingthebarcode'salignmentpatternsanddecodingthedata(SeeFigure5.3).Forinstance,thescanningsoftwareusedtoreadQRCodeshassomeprettyimpressivecapabilities.Oncethesmartphone'scameraprocessesthecode'simage,thesoftwaregoestoworkanalyzingtheimage.Bycalculatingtheratiobetweentheblackandwhiteareasofthecode,itcanquicklyidentifywhichsquaresarepartofthealignmentpatternsandwhichsquarescontainactualdata.UsingtheQRCode'sbuilt-inpatternsanderrorcorrection,thesoftwarecanalsocompensateforanydistortionorobscuredareasofthebarcode.Afterthesoftwarehasdigitally"reconstructed"theQRCode,itexaminesthejumbleofblackandwhitesquaresintheQRCode'sdatasectionandoutputsthedatacontainedwithin.

Ofcourse,QRCodeisonlyoneexampleofa2Dbarcode.Forinstance,theshipping

companyUPSusesaformatcalledMaxiCode,whichcanbescannedveryquicklyaspackagesflydowntheconveyorbelt,whereastheU.S.DepartmentofDefensehasadoptedDataMatrix,a2Dbarcodeformatcapableofholdingalotofinformationinaverysmallarea.Regardlessoftheformat,2Dbarcodescontainbothdataandbuilt-inpatternstohelpthescannerdecodetheinformationeachbarcodecontains,andinmanycases,onedevicecanreadavarietyofdifferentformats,eventraditional1Dbarcodes.

Figure5.3Diagramofa2Dbarcode

Ifyouwanttocreateyourown,you'llfindseveralgreat2Dbarcodegeneratorsonline.Theyletyouadjusteverythingfromtheformatyouwanttousetothesizeofthecode,sothenexttimeyou'reputtingupaflyerforyourlocalgaragesale,consideraddinga2Dbarcodewithyourhomeaddressatthebottom.Whoknowshowmanysmartphone-carryingbargainhuntersyoumightattract?

3．2DBarCodeAdvertising

Ifyoucanthinkofawaytosellaproduct,it'sprobablybeendone:blimpswithgiantcompanylogos,televisionsstreamingadstothebackseatsoftaxicabsandevenadvertisementsprintedinedibleinkonfood.Nothingisoff-limitsfromadvertisers.Buteventheyhavelongfacedadifficultchallengeastheytrytodeterminehoweffectivetheirphysicaladsreallyare;regardlessofthemedium,theycanonlyguesshowmanypeopleendupbuyingproductsorlearningmoreabouttheircompanybecauseofaparticularad.Thatallchangedwith2Dbarcodes.Forthefirsttime,companiescouldsimplyadda2Dbarcodetotheiradvertisementanddirectlytrackhowmanytimesconsumersscannedthecode.Ifsomeonedidscanit,theadvertiserscouldthentrackwhetherthatpersonwentontovisitthecompany'sWebsiteorevenpurchaseaparticularproduct.

Puttingthetechnologytouse,thefashioncompanyTommyBahamaaddeda2DbarcodeintoEsquireMagazinethat,whenscanned,tookreadersdirectlytoaWebpagefeaturingthepairofsunglassesshowninthemagazinead.Withoneclickoftheirmouse(orsmartphone),readerscouldthenbuythesunglassesforacool$138apop.NotonlydidthecodeshelpTommyBahamasellalotofsunglasses,theyalsohelpedthecompanylearnmoreabouttheircustomers,tellingthecompanywhattimeofdayandpartofthecountryanadwasscanned.

Targetisanothercompanyexploringthecapabilitiesof2Dbarcodes,addingQRcodestoitsmagazineadvertisements.Curiousreaderscanscanthecodesandinstantlywatchavideofromafamousinteriordesignerexplaininghowtousetheproductinthehome.Advertiserssaythislevelofinteractivityisperfectforanewgenerationoftech-savvyconsumerswhowantinstantaneousaccesstoproductinformation,reviewsandmore.Infact,thecodeshavebecomesuchapopularwaytoadvertiseinJapanthatthey'reevenfoundonbillboards,wheretheycanbescannedathighwayspeedsfromapassingcar.

Currently,thecodesaren'taspopularintheUnitedStatesastheyareinJapan,sodataonjusthowmanyadvertisersareusingthemandwhatsortofresultsthey'vebeengettingishardtocomeby.Still,asmorepeoplepurchasesmartphonesandlearnaboutthecapabilitiesofQRCodes,2Dbarcodesmaytakeoffmuchliketheir1Dpredecessors.

條形碼是光學儀器可以閱讀的數據表現形式，可以用來表示附帶它的物體的數據。起初，條形碼通過改變平行線的寬度和間距來表示數據，也被稱為線性或一維條形碼(1D)。后來其發展為矩形、圓點、六邊形和其他幾何形狀的二維條形碼(2D)。條形碼參考譯文雖然2D系統使用了多種符號，但仍然被稱為條形碼。原來，用叫做“條形碼閱讀器”的專用光學掃描儀來掃描條形碼；后來，將掃描儀和解釋軟件用在了包括桌面打印機和智能手機的設備上。

條形碼最早用于有軌電車的車票上，但沒有取得商業上的成功，直到它們被用于自動化超市結賬系統才成功，且條形碼在該系統中的應用已經非常普遍。條形碼(如圖5.1所示)也被廣泛應用于許多其他涉及自動識別和數據捕捉(AIDC)的任務?，F在無處不在的通用產品代碼(UPC)最早是在1974年6月用于Wrigley公司的口香糖包裝上。雖然后來其他系統也進入了AIDC市場，但是條形碼的簡單性、廣泛性和低成本限制了這些系統。直到21世紀最初的10年，在條形碼引入商業領域40年之后，像無線射頻識別(RFID)這樣的技術才進入商業領域。

1.應用

如UPC這樣的條形碼已經成為現代文明社會無所不在的元素，全世界的商店都熱衷于使用它。除生鮮外，雜貨店、百貨公司及超級市場中幾乎全部商品都使用UPC條形碼。這可以用來跟蹤商品和防盜(包括換定價標簽)，雖然扒手現在也可以打印自己的條形碼。另外，零售鏈會員卡(主要由雜貨店和如運動器材、辦公品和寵物店這樣特定“大包”的零售店發行)也使用條形碼來唯一地識別客戶，這樣可以了解到消費市場及客戶的個人消費模式。在購物點，通過登記的地址和電子郵件地址，購貨人可以得到折扣和特價優惠。通