Basicoverview
Colordesktoppublishingsystem,alsoknownasDTP,istheabbreviationofDeskTopPublishingbecauseitissmallandcanbeplacedNamedonthedesktop.
Thecolordesktoppublishingsystemisanewtypeofpre-pressprocessingequipmentintroducedinthe1990s.Itisacombinationofdesktopcolorseparationanddesktopelectronicpublishing.Itsadventfundamentallysolvesthedefectsofelectroniccolorseparationmachine'sweakabilitytoprocesstextandcannotmakenegativeorscientificnegativeswithintegratedgraphicsandtext.
Thecolordesktoppublishingsystemisdividedintothreeparts:input,processingandoutputfromtheoverallstructure.
Inputdevice
Thebasicfunctionoftheinputdeviceistoscan,separatecolorsandenterthesystem.Inadditiontotextinputandthecomputertypesettingsystemisthesame,imageinputcanuseavarietyofequipment,suchas:scanners,electroniccolorseparationmachines,cameras,plottersandsatellitegroundreceivingstations.Scannersaremorecommonlyused.
Therearetwotypesofscanners:platformtypeandrollertype.Thescannerusedincolordesktoppublishingsystemshouldhaveinputresolution,colornumberandscandensityrangesuitableforprintingrequirements.
(1)Inputresolution
referstothenumberofpointssampledperinch,expressedindpi.Dpiandthenumberofdotlineslpihavethefollowingrelationship:
dpi(inputresolution)=numberofdotlines×zoomrate×coefficient
Thecoefficientisgenerally1to2.Asthemagnificationincreases,therequiredresolutionincreases.Themagnificationofthereflectivemanuscriptissmall,calculatedat5times,1500dpiisenough.Theformatofthetransmissivemanuscriptissmall,anditiscalculatedat10times,and3000dpiwillwork.Somescannershavearesolutionof6000-8000dpi.Theactualresolutionuseddependsontheoutputresolutionandthezoomratiooftheimage.
(2)Colordigitsandscandensityrange
Colordigitsrefertohowmanybinarydigitsacertaincolorisrepresented,suchas8-bit,16-bit,24-bit,36-bit,etc..Thescandensityrangereferstothedensitydifferencebetweenthelightestanddarkestparts.Generally,thelargerthescanningdensityrange,themorecolordigits.Ifthedensityrangeisgreaterthan3.0,atleast10digitsarerequired.
Inaddition,thescannerisrequiredtoprovideastandarduniversaldataformat,accuratelyandreliablyacceptthecontroloftheworkstation,andhavethefunctionofautomaticenvironmentalcorrection,whichcancompensatefortheinterferenceoflightfromtheoutside,andatthesametime,ensurethatthescannercanreachUnderthepremiseofthemaintechnicalindicators,thefasterthescanningspeed,thebetter.
Processingequipment
Processingequipmentiscollectivelyreferredtoasgraphicworkstation.Thebasicfunctionistoprocessthemanuscriptdatathatentersthesystem,suchas:colorcorrection,revision,impositionandcreativeproduction,plustext,symbols,etc.,toformacompletepicture-textpage,andthensendittotheoutputdevice.
ThecomputeryouareusinghasaMaccamera(MAC)?PCsandworkstations,etc.Becausethehardwareequipmentandsoftwareavailablefordesktopsystemsareextremelyrich,whenselectinghardwareandsoftwaresuitableforprintingrequirementstoformasystem,severalissuessuchasprocessingspeed,processingcapacity,systemnetwork,andChineseenvironmentshouldbeconsidered.
(1)Processingspeed
Imageprocessingrequirespoint-by-pointprocessingofthepointsintheimage.Theamountofdataisverylargeandrequiresahighspeed.Ahigher-grademicrocomputershouldbeused.Orworkstation.
(2)Processingcapacity
Asimageprocessingrequireshigherandhigherinputresolutionandoutputresolution,thecapacityoftheworkstationtoprocessdataisincreasing.Atthesametime,itisalsorequiredtostorealargenumberofready-madeimagelibrariesandfontlibraries.
(3)Systemnetwork
Iftheworkofthecolordesktoppublishingsystemisnetworked,multiplecomputerswillworktogethertocompleteatask,andpeoplewillenjoyexpensivescanningandrecordingequipment.Therefore,itisnecessarytoselectareasonablesystemnetwork,networkserver,andfileservertosupportit.
(4)Chineseenvironment
Thedevelopmentofvariousforeignapplicationsoftwareisveryrapid,itisimpossibletoChineseizethenewapplicationsoftwareonebyoneandthenuseitinChina,whichrequiresgoodworkstationsWithitsChineseenvironmentandgoodcompatibilityandopenperformance,itcandirectlytransplantthenewlyopenedWesternlanguagesoftwaretothesystem'sChineseenvironmentwithoutanyproblems.
Outputdevice
Theoutputdeviceisthedevicethatthecolordesktoppublishingsystemgeneratesthefinalproduct.Itismainlycomposedofahigh-precisionlaserimagesetter(alsocalledagraphicrecorder)andRIP(RasterImageProcessor).Thelaserimagesetterusesalasertogatherthebeamintoalightspot,hitthephotosensitivematerialtomakeitsensitive,anddevelopitintoablackandwhitenegative.RIPacceptsthelayoutofPostScriptlanguage,convertsitintoarasterimage,andthenoutputsitfromtheimagesetter.(PostScriptisapagedescriptionlanguagedevelopedbyAdobe.Itisnowacceptedbymanypeopleandhasbecomeastandard.)RIPcanbeimplementedbyhardwareorsoftware.ThehardwareRIPiscomposedofahigh-performancecomputerplusadedicatedchip.ThesoftwareRIPiscomposedofahigh-performancegeneral-purposemicrocomputerpluscorrespondingsoftware.Inordertomeettherequirementsofimageprocessingforprinting,theoutputresolution,outputrepeataccuracy,outputscreenstructure,outputspeedandotherperformanceindicatorsofthelaserimagesetterandRIPmustbeconsidered.
(1)Outputresolution
Thetextresolutionisgenerally700～900dpi,theimageresolutionis60lines/cmdots,theresolutionrequires2400dpi,70lines/cmdots3200dpiisrequired.
(2)Outputrepeatability
Forhigh-endexquisiteprints,themaximumallowableerrorofrepeatabilityis5μm.Forgeneralprintedmattersuchasmanuals,booksandperiodicals,therepeataccuracyisallowedtobe20-25μm.Forlow-gradeprintedmattersuchascolornewspapers,theallowableerrorofrepeatabilityis25-50μm.
(3)OutputScreeningStructure
Itcanoutputdifferentdotlinesanddotshapes.Inordertoensurethatthecolorimageiscopiedwithoutobvioustortoiseordensityfluctuations,theoutputdeviceisrequiredtoproducedotswithgoodprintingperformance.
(4)Outputspeed
TheoutputspeeddependsontheperformanceofRIPandgraphicrecorder.ThehardwareRIPspeedisfast,andthesoftwareRIPspeedisslow.Underthepremiseofoutputtingthesamequalitycolorseparationfilm,thefasterthebetter.
Inaddition,theoutputdeviceshouldalsohaveastandardinterfaceandtheabilitytooutputChinesecharacters,andtheoutputformatcanmeettherequirementsofprinting.
Theoutputdevicesofthecolordesktoppublishingsystemalsoincludevariouscolorprinterssuchaslaserprinters,inkjetprinters,thermalprinters,andvariousmultimediacarriers(slideshowmaker,CD-ROM,videorecorder,etc.).
High-endnetworking
Thecolordesktoppublishingsystemisconnectedwithvarioustypesofexistingelectroniccolorseparationmachines,calledhigh-endnetworking,whichisanotherwayofworkingfordesktopsystems.
Whenusinghigh-endnetworkingtoobtainhigh-qualitygraphicnegatives,theelectroniccolorseparationmachineinterfacemustsolvetwokeyproblems.First,thespeedissue.Sincetheelectroniccolorseparationmachinecannotbecontrolledwhenitisinandinthestate,theinterfaceandtheinterfaceworkstationmustbefastenoughtoreceivethescanningdataoftheelectroniccolorseparationmachineandsenddatatotheelectroniccolorseparationmachineatthesametime.Second,thewaytooutputnegativesinoneimageandtext.Ifthedotgeneratoroftheelectroniccolorseparationmachineisusedtogeneratedots,onlyahigh-resolutioninterfaceisaddedtojointlycompletetheoutputoftheimageandtext.Ifyoudonotusethedotgeneratoroftheelectroniccolorseparationmachinetogeneratedots,andonlytreattherecordingpartoftheelectroniccolorseparationmachineasanimagetypesettingmachine,youneedtoaddaRIPtoprocessthedotsandtext,andthedesktopsystemusestheelectroniccolorseparationmachinethroughRIP.
High-endnetworkinghasformedafull-pageimpositionsystemwithageneral-purposecomputerasthecore.Itnotonlytakesadvantageofthehighinputresolutionoftheelectroniccolorseparationmachineandgoodimageprocessingquality,butalsointegratestheadvantagesofthedesktopsystemthatcanprocessgraphicsandtextatthesametime.Itopensupanexcellentwayformanufacturerswithelectroniccolorseparationmachinestoimprovetheabilityandefficiencyofcolorplatemaking.