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Pain%ng:SchoolofAthens,Raphael,1510‐11,PlatoandAristotlecentralfigures.

Itisclearthatscholarshipmethodologyhaschangedovertheages.ItshouldcomeasliAlesurprisethatinthisageoftechnologicaladvancesthatthenewgenera%onislookingtowardon‐linedigitaltoolstosupportandexpandtheirscholarship.AtNYUithasbecomeapparentthatthereisanincreasingrolefordigitalmigra%onofanalogmaterial(books,archivalmaterial,andmul%media)toaccessibledigitalformats.Aseduca%onbecomeslessaboutloca%ondigitallibrariesbecomeawayofsharingaknowledgebasewiththenextgenera%onofscholars.

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Veracity,context,andcomprehensivenessmaAerastheyalwayshaveinscholarship.Thetruth,thatisthelookandfeeloftheoriginal,needstobeguardedduetotheflexibilityofdigitalfiles.Alsoofconcernisthelongevityofdigitalfiles.Newdigitalsurrogatesmustbemadetowithstandthetestof%mesothataccesstothematerialcanbeongoing.Microfilmlasts500yearsifcorrectlymade.Adigitalfileneedstobecreatedtobesttechnicalbenchmarksandtointerna%onallyunderstoodstandardssothatittoocanlast.Standalonewebsitesareunlikelytolastlongandwillprovideonlytemporaryaccess.Createongoingaccessadigitalprojectneedstobecarefullyconsidered.

Ins%tu%onshavetodothebestthattheycanaboutsavingdigitalfilesthatwerecreatedbeforedigitalstandardswerefirmlyinplace.Insomecasestheselegacyfileswillneedtobenormalizedtocurrentstandardssothattheycanbepreserved.

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Justasyoucandriveacarwithoutunderstandingthemechanicsofaninternalcombus%onengine,youcanalsopar%cipateinguidingdigitalprojectspar%cularlyintermsofcuratorship,withoutknowinghowtocreateeachpartofadigitallibrary.Specialistswillbeneededtocompleteanydigitalproject.

Selec%ngthecontenttosaveisen%relywithintherealmofthesubjectspecialist.Howtosavethatmaterialneedstobeguidedbydigitallibrarytechnicalservicesandconformtostandards.Tocreateonlinecollec%onsacleardigitalcollec%onpolicymustexist.Tocon%nuetoaccessonlinecollec%onsanumberofdifferentkindsofmetadatawillbeneededincludingcleardiscovermechanisms,descrip%vemetadataandtechnicallywellformedfiles.

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Accessprojects,whileeasilylaunchedareunlikelytopersist.Whateveraccessiscreated,eitherviaFlickr,afindingaid,oraAachingtoanonlinecatalog,theremustbeanunderlyingpreserva%onfilethatisheldinarepositorywithsufficientmetadatafordiscoveryoverthelongterm.

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Thefollowingfindadiscussionaboutbasiccharacteris%csofimagefilesthatarecreatedforpreserva%on.Conserva%on,thefirstconcernforrarephysicalmaterialisparamount.Digi%za%onshouldnotdamagetheoriginalar%fact.Onlyonedigi%za%onofrarematerialsshouldbeplannedasawayofconservingtheoriginalforthefuture.Goodtechnicalcapturetakesnomore%methatpoorlowresolu%oncapture.Truepreserva%onimagingwillrequiregoodequipmentandsignificantplanningbutcanbeextremelyefficientoncesetupgiventhenewgenera%onofequipment.

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Accessed8/3/2012,hAp://brb.sdsc.edu/,fromSustainableEconomicsforaDigitalPlanet:EnsuringLong‐TermAccesstoDigitalInforma<on,pg19,finalreportoftheBlueRibbonTaskForceonSustainableDigitalPreserva%onandAccess.

Itisimportanttorememberthatdigitalfileswilllivebeyondtheiroriginaldigi%za%onneed(forexampleforcoursework)andcon%nuetobeusedbyscholarsindifferentwaysover%me.Sincethoseusescannotbepredicteddigi%za%onneedstobedonetoincludefutureneeds.Highresolu%onimageswithcorrectcolorinforma%onabouttheoriginalwillbekeytothisongoinguse.Validfilesthatcancon%nuetobeusedover%mearerequiredaswell.

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Itisespeciallyimportanttothescholarthatthedigitalcapturebeastruthfultotheoriginalaspossible.Thereshouldbenodigitalfixingofrips,cleanupofstains,enhancingtextorcolor.Sincescholarswillbeusingthismaterialtostudymanydifferentaspectsofthematerial,forexamplefadingofamanuscript,itisimportantnottousedigitaltoolstomanipulatethedigitalimage.

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AtNYULibrariesanumberofourmaterialsarear%stmade.Ofenthecreatorhasmanipulatedcolororotheraspectsoftheoriginal.Themigra%onspecialistwillrespecttheinten%onsofthear%st/creator.

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Fullcoloristhemostdesirabletechnicalspecifica%onforresearchers.Fullcolorfilesmaintainthelookandfeeloftheoriginalcontentandsubstrate(inthiscasepaper)andwillallowresearchestousetheseimagesasdigitalsurrogatesfortheoriginalmaterialsinmanycases.Grayscale,thoughfarlessusefulhasbeenusedbysomeforpreservinglegibilityofthecontent.Bi‐tonalcaptureisnearlyuselessandofenverydifficulttoread.

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hAp://afghanistandl.nyu.edu/

Thissiteisanexampleofapreserva%onprojectwithanaccesscomponent.Pleasenotetheamountofmetadatathattravelswiththeindividualbooksaswellasthepermanentcita%onforscholarlypublica%on.

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hAp://dlib.nyu.edu/rosie/

Thissite,similarly,isapreserva%onprojectwithanaccess“frontend”.

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Agreatdealofmetadataisneededtoiden%fyandunderstanddigitalprojects.Descrip%vemetadataisthedomainofthesubjectspecialist/cataloger.Inthissessionotherclassesofmetadatawillbediscussed,thoughtechnicalmetadatawillbeexploredmoredeeply.Expertsinmetadataissuesareneededtobuildatruedigitallibrary.Somemetadatawilllikelybeneededeveninaccessprojects.

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Followingfindabriefoutlineofbasicinforma%onneededtohavetodiscussdigitalimagingwithyourdigitallibraryorvendor.Aswithalltoolsgoodimagingcanonlybedonewithgoodequipment.

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Adigitalpictureisnotaphotograph.Itisbinaryinforma%onthatisinterpretedbyagraphicaluserinterface(GUI)thatisavailableonyourcomputer.WithouttheGUIdigitalphotographswouldbeunreadable.Thepixelisthebasicunitofdigitalimaginganditisrepresentedbyonecoloronly.

Alldigitalimagesare,attheircore,binaryinforma%on.

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Othercommonformatssuchasjpegs,pngs,jpeg2000arenotacceptableforpreserva%onworkastheyarelossy.Lossyfilescontaincompressionthatchangesthepixelswitheachsave.Followingseeanexampleofjpegcompression.

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Lossycompressiondamagesafileirreparably.Savingafileoverandoverwillexacerbatethis.

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Exampleofjpegcompressionerrors.

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Apar%cularlytrickypartofdigitalimagesistheirrela%onshiptothecolorofthesourceobject.Acolorspecialistshouldbeconsultedtomakesurethatyourequipmentischaracterizedandcalibratedandthatanappropriatecolorspaceisembeddeddirectlyintothedigitalimage.AtNYULibrariesweembedallimageswiththeinterna%onalcolorspaceCIERGBwhichisastandardheldbytheCommissionInterna%onaledeI’Éclairage.AdobeRGBisanotherofenusedcolorspaceforarchivalwork.Aboveisanexampleofonegenera%onoflossfromanunmanagedcolorfile.

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Badcolormanagementwillobscurethecoloroftheoriginalmakingitmuchlessusefulforresearchers.

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Colormanagementisascience.Thereisimportantmathema%calmappingthathappensindigitalimagesthatmustbemaintained.

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Mostreflec%vematerialcanbeimagedat400or600pixelsperinch.Moredetailedoriginalssuchasslides,glassnega%ves,transparenciesandotherswillneedamuchhigherresolu%on(ofenupto4000pixelsperinch)tocaptureallofthedetailfromanoriginalanalogsource.

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600ppiversus72ppi

Therearesomeotherimportanttechnicalcharacteris%cstoconsider.Imagingspecialistswillbeabletodiscussthesecharacteris%cswithyou.PleaseknowthatcleaningpicturesupinimagingsofwaresuchasAbodePhotoshopaferthefactresultsinbadlydamagedfiles.Correctfilesneedtobemadeatthe%meofcapture.

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Thisinforma%oniscreatedbythepeoplewhounderstandthematerialthebest,thesubjectspecialistorcataloger.

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Thistypeofmetadataisgenerallycreatedbydigitallibrariesorvendorswhoaremigra%nganalogmaterial(books,documents,mul%media)todigitalfiles.

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Digitalobjectstonothavetheintui%vestructuringofthesourcematerial.Mul%‐volumesets,foldoutpages,inserts,materialsrelatedtomul%media,etc.mustallbestructuredsothatthedigi%zedobjectcanbeunderstoodclearlybyresearchers.

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Thesetypesofspecializedmetadataarebesthandledbyexperts.Rightsmetadatahelpdigitallibrariescontrolitemsthathavenotclearedcopyright.

TopreservedigitalfilestheyneedtobeheldinanIT(Informa%onTechnology)structurethatpreservesthefilesandtheinforma%onaboutthefiles.Thisisaverycomplexfield.Followingfindanoverviewofinforma%onaboutrepositoryneeds.

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Valida%onistheprocessofevalua%ngadigitalobjecttodeterminewhetheritmeetsthestandardthatitpurportstomeet.Forexampleascannercanmakeanimagefilesuchas“object.%f”.ThisfilemayopeninAdobePhotoshopwhichisbuilttoopenanythingitcan,validornot.Thefilemayhoweverbefundamentallyflawedoroutofstandard.Over%mesuchinvalidfileswillbecomeillegible.jHove,hAp://hul.harvard.edu/jhove/,createdbyHarvardUniversityLibraries,willvalidateanimagefileandinformyouthatyourfileis“well‐formedandvalid”.Thisisacri%calstepincrea%ngpreserva%onimages.

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NYULibrariescurrentlyusesSHA‐256checksums.RunningchecksumsinaccordancewithgoodITprincipleswillguaranteethatyourfileshavenotchangedover%me.

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Fromthelongviewweneedtorememberthatpreserva%onisaboutsavingnotonlytheinforma%onobject,butalsoallthatsupportsit.Thisincludesacomplexhierarchyofinforma%onthathastobepreservedtoallowthedigitalfiletobeperceivabletotheresearcher.Toseetheimageofadigi%zedpagethescreenimagehastobecomprehended.Behindthatlieslayersofgraphicalinterfaces,metadatainstruc%ons,binaryinforma%onetc.Allhavetobepreservedandmanagedsothattheendresultishumanreadable.

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hAp://www.oclc.org/research/publica%ons/archive/2000/lavoie/

Apreserva%onrepositoryismuchmorethanabackedupcomputer.

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Thankyou.

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