诺基亚-Lumia1020-相机说明书

PUSHINGTHE

BOUNDARIESOF

DIGITALIMAGING

ThiswhitepaperintroducesNokiaLumia1020andits

newhardwareandsoftwarecamerainnovations.The

NokiaLumia1020re-inventszoombycombiningavery

largesensorwithOISforthefirsttime.Alsoitpushes

theboundariesofsmartphonecreativephotography

withanewintuitivetouchUIthatprovidesmanualcon-

trolsforshutterspeedandothercontrols.

ThiswhitepaperprovidesabackgroundonhowourPure-

Viewtechnologyhasevolved,andthenintroducesthe

newHW(sensor,lenses,OIS)anddescribestheevolved

zoom.NokiaProCameraUIanditsmanualcontrolsare

introducedtogetherwithanewmethodoflosslessed-

itingofyourimages.

CONTENTS

Background4

Bestofbothworlds:Sharpnessandlowlight4

Sharpnessismorethanjustmegapixels5

Why5MP?5

Oversamplingresultsin5MPphotoswithamazingdetail6

Highresolutionzoom6

Gettingridofhand-shake8

Photosinthedark8

Backsideilluminatedsensor9

Exposuretime9

Flash9

Reallifesharpnessmeasurement9

NokiaProCamera11

Zoomreinventedandreframing12

Photographytoolsandcreativecontrol14

Manualcontrols:EV,shutterspeed,ISO,focus,WB15

NokiaProCameraVideo16

NokiaRichRecording16

Photoexamples18

Keytechnologiesandspecs21

Credits22

BACKGROUND

TheNokia808PureViewcameraphone,launchedin

2012,includedworld-leadingadvancesinimagequali-

tyintermsofresolution,sharpnessandclarity.Innova-

tiveoversamplingtechnologyprovidedalevelofimage

detailpreviouslyunseeninmobile,orevensmallscale,

digitalimagingsystems.Inaddition,pixeloversampling

combinedmanypixelstocreateasinglesuper-pixel.

Thisallowedustokeepvirtuallyallthedetailbuttofilter

visualnoiseawayfromtheimage.Imageslookedmore

naturalandwerepurer,givingamoreaccuraterepre-

sentationoftheoriginalsubjectthanhadeverbeen

achievedbefore.

Nokia808PureViewwaspioneeringandprovided

benchmarkimagequality.Wereceivedextremelypos-

itivefeedbackbutuserskeptchallengingusforeven

betterlowlightimagingcapabilities,especiallywithout

flash.Thisfeedbackinfluencedthedevelopmentofour

secondgenerationPureViewphone–theNokiaLumia

920PureView.

Figure1.ThelatestgenerationBSIsensorcapturesalotoflight.Illustrationonly.

TheNokiaLumia920wasthefirstglobalsmartphone

toimplementopticalimagestabilization(OIS)toseta

benchmarkinlowlightimagequality.Weimplementedaward-winningPureViewinnovationsasthestarting–meaninghighresolutionzoomingandpixeloversam-

aback-side-illuminated(BSI)sensorwithf2.0aperture,pointtocreatetheultimatenextgenerationimagingpling–plusnewinnovationsinarevised,moremodern

opticalimagestabilisationandthemostsensitivepixelssmartphone.LetusintroducetheNokiaLumia1020.cameramodule.

seeninacamera.AllthiswasbuiltontopoftheWin-

dowsPhone8platformforseamlesssocialmediashar-TheNokiaLumia1020introducesthesecondgener-

ing,andequippedwithNokia’sownstate-of-the-artationofouropticalimagestabilization(OIS)system

imagingalgorithms.ThisallowedtheNokiaLumia920Bestofbothworlds:firstfoundintheLumia920PureView,toprovideanew

–andthemorerecentlyannouncedLumia925and928Sharpnessandlowlightbenchmarkinimagestabilisationsystems.Weinclude

–torevolutioniselowlightimaging.themostsophisticatedxenonflashandvideo-lightLED

Thesecondgeneration41megapixelsensorusestheimplementedonanyNokiaphonetohelpusersfreeze

In2013wehadtwokindsofcameraphoneinourPure-latestgeneration1.1micronback-side-illuminated(BSI)themoment.

Viewrange,providingimagingcapabilitiespreviouslypixels,providingexcellentnoiseperformanceaswell

unseeninmobile,eachoneleadingdifferentareasofasbenchmarkresolution.Thesensorformatis1/1.5”Oneofthecriticaldesigndecisionsinacameraisbal-

digitalimaging.Oneprovidedbenchmarkperformanceanditisuptofivetimeslargerthantypicalsmartphoneancingthesubjectiveimagesharpnessandnoiseper-

incapturingdetails,andanothersetrecordsinlowlightsensors.Theredesignedsensorprovidesalltheimag-formance.Imagesharpnessandlowlightperformance

imaging.ThenaturalnextstepwastotakethosetwoinginnovationsintroducedwithNokia808PureView(noiseorgrain)aretwosidesofthesamecoinincamera

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systemsanditisextremelydifficulttoachievebench-

markperformanceinbothsimultaneously.Howeverthis

isexactlywhatwehavedonewiththeNokiaLumia1020.

Sharpnessismorethanjust

megapixels

Resolutionisthesumofseveralpartsintheimaging

chain,startingfromhowwecaptureimages,howmuch

hand-shakeisinvolved,andendingwithtechnicalfunc-

tionsincludingthecameraoptics,theimagesensor,and

thealgorithms.It´snotenoughtojustincludeahigh

megapixelsensor–thelensesconveyingtheimageto

thesensorhavetobeofequallyhighquality.

TogetherwithourpartnerCarlZeiss,weyetagain

pushedthelimitsofopticaldesigntomatchthereso-

lutionofthe41megapixelcamerasensor.Toprovide

thebestopticalresolutionweincreasedthenumberof

lensesusedfromthefiveintheaward-winningNokia

808PureView,tosix.Thefirstlenselementismadeof

highprecisionglass,andfiveofthelensesaremould-Figure2.SixCarlZeisslensesincludingahigh-precisionglasselement.Illustrationonly.

edhigh-performanceplastic,takinglensmanufacturing

precisiontothenextlevel.tiontothe38MPand34MPfull-resolutionimages,theWhy5MP?

Lumia1020cameracaptures5MPoversampledimages

Thelensesarephysicallyverybigforasmartphone,andsothateverypixelinthe5MPimagehasbeencreated5MPisthesweetspotforimagequalitythatiseasyto

theopticalassemblyaloneisunique.Butthatisnotall.usingthedatafromuptosevenpixelsofthesensor.shareandprintableuptoA3size.Andbecauseour5MP

WeputthewholesysteminsideacompletelynewkindTheoversamplingtechnologyensuresthatthese5MPimagescondensetheinformationfromthe41MPsen-

ofopticalimagestabilisationsystem,whichusesanimagesareincrediblysharp,naturalandlownoise.Thesor,theyhaveamazinglyhighimagequality.

extremelyhighaccuracysensingsystemlinkedtoverybestpartisthatthecamerasavesboththefullresolu-

The5MPimagesgetthefullbenefitoftheoversampling

smallmotorswhichactivelymovethelens.tionandoversampledimagesimultaneously.

technologyandtheirqualityiswayabovethatproduced

byanytraditionalimagingdevice.Inadditiontoover-

Theextremelysharpimageprojectedbythesix-elementThisisreferredtoasdualcapture.Itenablescreative

post-processingwhilestillallowinguserstoshareasampling,the41MPsensorcanalsobeusedforlossless

lenssystemisrecordedbythesecondgeneration41MPorhighresolutionzooming(seepage6).

BSIsensor,capturingeventhesmallestofdetailsinthehigh-qualitysmallfilesizeimagestraightaftershoot-

scene,includingdetailnotvisibletothenakedeye.ing.

The41MPsensorcancapture34MPand38MPimage

filesat16:9and4:3aspectratiosrespectively.Inaddi-

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Oversamplingresultsin5MPphotoswith

amazingdetail

Intraditionalimagingsystems,thetrueresolutionofthe

systemislowerthanthatofthenominalsensorresolu-

tion.Thetraditionalcamerasensorresolutionmaybe

5MP,butitdoesnotreallycapturephotosthathavefive

millionpixelsofindependentdata.Thedataisspread

acrossmultiplepixelscausing,forexample,blurringand

artifacts.Therearetwotechnicalreasonsforthis:oneis

relatedtotheopticsdesignandaliasing,andtheother

tothewaythesensorsamplesthedatawithBayerco-

lourfilters.Atraditional5MPcamerahasonly2.5million

greenpixelsand1.25millionredandbluepixels1for

example.SeeFigure3foracomparisoninsharpnessofFigure3.Comparisonofastandard5MPimageandanoversampled5MPimage.

astandard5MPimageversusanoversampled5MPim-

ageandFigure4foranillustrationofhowoversampling

reducesnoisecomparedwithastandardsensor.

TheoversamplingtechnologyintheLumia1020makes

itpossibletosolvebothoftheseissues,andenables

fulldetailstobecapturedwiththe5MPimage,visible

asamazingsharpness,naturalnessandlownoise.ItisOutputfromastandard5MPsensorshowsnoiseasvarianceinthesignal

physicallyimpossibletocapturethiswithatraditional

5MPcamera.

Outputfromahighresolutionsensorbeforeoversampling

Outputafteroversamplingreducesthenoise

Figure4.Illustrationofhowoversamplingreducesnoisecomparedwithastandard5MPsensor

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Highresolutionzoom

ZoomQualityComparison

Inadditiontooversampling,thelargesensoralsoallows

forhighresolutionzoom.Asyouzoomthereisnodrop

inthedefault5MPresolution;inotherwordsthehigh

resolutionzoomislossless.Thelevelofpixeloversam-

plingishighestwhenyou’renotusingthezoom.Itgrad-

uallydecreasesuntilyouhitmaximumzoomwherethe

pixelsstartbehavinginamoreconventionalway.The720p

1080p

relationshipbetweenzoomlevelandoversamplingisOversampling5MP

showninFigure5.

1:10246

Atmaximumzoom,theLumia1020systembehavesZoomfactor

morelikeatraditionalcamera,buttherearestillsome

advantages:asonlythecenterpartoftheopticsisUpscaling

used,theopticalandgeometricdistortionsareminimal

andvignettingisnegligible.

Theproblemwithtraditionaldigitalzoomisthatthe

zoomlevelisextremelylimitedwithoutclearlyvisibleTraditional8MPsensor

lossofimagedetails.Thishappensbecausethesystem

needstozoomfurtherthantherequiredoutputresolu-

tionofthefinalimage,andthecameraneedstoupscale

thecapturedimagetoachievethatresolution.Inprac-Figure5.Oversamplingvs.highresolutionzoominthecaseofLumia1020(blue)comparedwithconventionaldigitalzoom

ticethismeansthat,forexample,a12MPdevicemight(orange).Highoversamplingmeanshighimagequality.

captureonly4MPafterzooming,andthe4MPimageis

thendigitallyup-scaledbackto12MP.Thisup-scalingtimes.Alsowithtraditionalzoomlensesthemacrodis-HoweverwithNokiaLumia1020,theaperturestaysat

hasasignificantimpactonimagesharpness.Howevertanceoftenchangeswhilezooming,whichmeansthataconstantf2.2throughoutthezoomrangewhichis,

withNokiaLumia1020weneverneedtoupscalethefi-thephotographerneedstochangethephysicalcam-inSLRterms,25/27-69/74mm(16:9/4:3)forstillsand

nalimages,becausethestartingresolutionisalreadysoera-to-objectdistancewhilezoomingformacroshots.25-100mmforFullHDvideo.Thesezoomrange/aper-

massive.InFullHDvideomodethemassiveresolutionInaddition,mostopticalzoomlensessufferfromoverallturecombinationsarerare,andexpensiveeveninthe

meansthatthecameraneverzoomsfurtherthanthereducedsharpnesstowardsthelongendofthezoomSLRworld.

requiredtwomegapixels,whichensuresthattheresolu-range;thisisbecauseofopticaldesignissuesthatof-

tionstaysexcellentthroughoutthezoomrange.tenproducedifferentdistortionsatthewideangleendAlsoastheaperturestaysthesamethroughoutthe

comparedtothoseatthetelephotoendofthezoomzoomrangeintheLumia1020,themacrodistanceof

TheadvancedPureViewmethodoflosslesszoomingalsorange,whichinthecaseofFullHDisupto4X.SeeFig-~15cmalsostaysthesame.WithNokiaLumia1020

providesmultiplebenefitsovertraditionalopticalzoom.ure6foravisualonthemaximumhighresolutionzoomweareactuallyusingthecentrepartofthelenswhere

Traditionallytheapertureofopticalzoomsystemsbe-for5MP(3X)and720Pvideo(6X)comparedwiththefulldistortions,diffractionsandlensshadingaresmallest,

comessignificantlysmallertowardsthelongendoftheresolutionsensorin16:9and4:3aspectratios.givingextremelyhighlevelsofresolveddetailsanddis-

zoomrangecomparedtothewideend.Thishasabigtortion-freeimagesandvideosthroughoutthezoom

impactonlowlightperformanceandusableexposurerange.

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TheadvantagesoftheNokiaLumia1020zoomcompared

toanopticalzoomare:7136

4:3FullResolution

•Theaperturesizeofatypicalopticalzoomdrops5360

dramaticallywhenzoomedin.Forexample,atypical16:9FullResolution

opticalzoomcanhaveaperturesizef2.8inwide,but

itcandroptof6intele.Thismeansthatthecamera

needsalmostafivetimeslongerexposuretimeinthe

teleposition.Theproblemismultipliedbythefact

thatthecameraismostpronetohand-shakeinthe

teleposition–andtheusershouldactuallyuseshort-5MP,3xzoom

erexposuretimestoavoidblurredimages.IntheLu-

mia1020,theaperturesizeandexposuretimesstay720p,6xzoom

thesamethroughoutthezoomrange.4352

•Thesmalleraperturesizerequiredfortelephoto

shotswithanopticalzoomcameraincreasesdiffrac-

tionwhichcanmakeimagesblurryevenwhenthereis

nohand-shake.

•TheopticsinLumia1020aresimplifiedandrobust

comparedtoopticalzoom–akeyenablerforthe

amazingimagesharpness.

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•AstheNokiaLumia1020isbasedonahugeimage

sensor,itenablesmuchhigherperformanceand

oversamplinginthewide-angleposition.Figure6.Thehighresolutionzoomislimitedto3Xforstills,ensuringthattheoutputis5MP.FullHDvideocanbezoomed4X

whereas720Pvideohas6Xzoom.

•Lumia1020macrodistancestaysthesamethrough-

outthezoomrange.

Gettingridofhand-shakethismeansisthatweareabletocanceloutlargermove-

mentscomparedtotraditionalOISsystems,enablingsu-

•Asthezoomingisdonewithoutmechanicallymoving

per-sharpimages.

anyparts,itissilent,fast,andintuitive.AdditionallyLensdesignandsensorresolutionareoftentheonlyfac-

theLumia1020slidezoomcanbeoperatedbyusingtorsconsideredwhendiscussingcamerasharpness,but

TechnicallyourOISisthebarrelshifttypefirstseenin

onehandonly.anequallyimportantfactoristotallyneglected–hand-

shake.EventhesharpestopticalsystemsintheworldtheNokiaLumia920.(Otherwaysofmakingopticalim-

agestabilisationsystemsincludebarreltilt,sensortilt

•Dualcaptureallowsforpostcapturezoomingandcan’tcaptureasharpimageifthecameraismovedduring

ormoduletilt,butforourpurposesbarrelshiftgives

reframing.Moreonthisinthereframingsectiononcapture.WehaveimplementedacompletelynewOISsys-

thebestquality.)IntheLumia1020theopticsaremuch

page12temtoovercomethis.IntraditionalSLROISsystemsjust

onelenselementinthelensstackismovedtocounteractbigger,andaddingOIStechnologytoopticsofthatsize

hand-shake,butinourOISthewholeopticalassemblyisrequiredsomereallycleverengineering:thewholelens

movedtocanceloutunwantedcameramovements.Whatsystemisrestingontopofballbearingsandisactively

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movedwithverysmallmotorstocounteracttheunwant-Photosinthedarktotransferthephotonsoutfromthepixel.Withtradition-

edcameramovementsdetectedbyagyroscope.alpixelsallthesewiresarelocatedontopofthepixelsand

lightmustbypassthewirestoreachthephotosensitive

Ifyoulightlywobblethephoneandlistentothecamera,Thestandardfactorusedfordetermininggoodlowlightareaofthepixel.Weusedamodern-generationBSIsen-

youcanactuallyhearthemodulethatabsorbstheshak-performanceistheamountofvisiblenoiseintheim-sorwhereallthesewiresarelocatedunderneaththepix-

ingofyourhand.Oncethecameraisactivated,givetheagecaptured.Butthereisalotmoretoitthanjusttheel.Withthisdesignasignificantlylargeramountoflight

phonethesamewobbleandthemagnetskickinandsoakamountofnoise.canactuallyreachthephotosensitiveareaofthepixel.

upthemovements.Thisagainmeansthatwecanamplifythesignalcreated

Backsideilluminatedsensorbymuchlowerlevelsoflight,significantlyreducingthe

amountofvisiblenoise.

Itisextremelydifficulttomakeahighresolutionsensor

withjustasmallamountofvisiblenoisebecausepixelsExposuretime

mustbekeptsmalltokeepthesensorsizereasonable.

Thesmallerpixelsizeisespeciallyproblematicwithtra-Anotherextremelyimportantfactorcontributingtolow

ditionalfrontsideilluminated(FSI)sensors,becauseeachlightperformanceistheexposuretime.Acameracanbe

pixelneedsmanywirestopowerupthephotodiodeandcomparedtoadamwheretheshutterplaystheroleofthe

gate.Thelongerthegateisopen,themorewatercanflow

throughit.Inacamera,thelongertheshutterisopenthe

morelightcanbegatheredbythesensor.

However,iftheshutterisopentoolong,thecapturedim-

agecansufferfromhand-shake,whichmeansreduced

sharpness.WithitsOISsystem,theNokiaLumia1020

cameracanactuallytolerateuptoof3-5timeslongerex-

posuretimescomparedtotraditionalmobilecameras–a

significantbenefitinlowlightsituations.UsingtheLumia

1020togetherwithatripod,userscanmanuallysetthe

exposuretimeupto4s,whichallowsyoutotakeamazing

imagesinnearlycompletedarkness.

Flash

Whendiscussinglowlightperformanceit´sonlynatural

toalsoconsidertheflash.Eventhoughmanypreferthe

naturalambientfeelinginimagescapturedwithoutflash,

evenwiththeverybestofcamerasweoccasionallyrun

intosituationswheretheuseofflashismandatory,espe-

ciallyifthetargetismoving.Flashperformanceisoften

assessedbycomparingthelightoutputofdifferentflash-

es,howeverflashpulsedurationisanequallyimportant

parametertoconsider.

Figure7.Cleverengineering:Ballbearingsfloatthelargelenssystem.Illustrationonly.

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WiththeLumia1020weuseano-compromisexenon

flashwithveryhighlightoutputandextremelyshortImagesharpnessmeasuredwith

flashpulseduration.Highflashoutputprovidesexcel-handshakeasfunctionofilluminance

lentilluminationtotargetsthreemetresaway,andthe

shortpulseofthexenonflashensuresthatthefinal

capturedimageisextremelysharpwhilepreservingthe

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ambientlightingofthebackground.Lumia1020