Part II: Photo Editing
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UCSD School of Medicine, Office of Educational Computing Helene Hoffman, PhD <[email protected]> Photoshop Version PS CS3 Part II: Photo Editing M.E.D.S. Workshop, March 2009 Section I: Basic Image Editing Process 1. Open 2. Create copy for editing 3. Rotate 4. Adjust brightness and contrast 5. Adjust color balance 6. Crop 7. Resize 8. Sharpen 9. Save (for print, email, web, etc) Section II: Techniques that address specific problems/needs 1. Dust & Scratches filter 2. Clone Stamp tool 3. Healing Brush tool 4. Spot Healing Brush tool 5. Burn or Dodge tool Section III: Creative techniques with filters What photo-editing program should I use? Adobe Photoshop is the leading graphics editing program used by professionals and serious amateurs. It is complex and expensive, but very powerful. There are many alternatives with scaled down features and prices, and some are even free. Examples of consumer‐level products include Adobe Photoshop Elements ($70.00 via UCSD Bookstore), Google Picassa (free). There are also a growing number of online editors. CNET.com recently reviewed 15 popular products (http://cnet.com). What is the best way to manage digital image collections? Many of the consumer level photo‐ editing programs also provide tools for browsing, sorting, and applying key words and descriptions. In addition to Photoshop Elements and Picassa cited above, there is iPhoto (Mac), Windows Live Photo Gallery (Win), Corel Media One Plus (Win), Shoebox (Mac), and many more.
Transcript of Part II: Photo Editing
UCSDSchoolofMedicine,OfficeofEducationalComputing HeleneHoffman,PhD<[email protected]>
PhotoshopVersionPSCS3PartII:PhotoEditingM.E.D.S.Workshop,March2009
SectionI:BasicImageEditingProcess
1. Open2. Createcopyforediting3. Rotate4. Adjustbrightnessandcontrast5. Adjustcolorbalance6. Crop7. Resize8. Sharpen9. Save(forprint,email,web,etc)
SectionII:Techniquesthataddressspecificproblems/needs
1. Dust&Scratchesfilter2. CloneStamptool3. HealingBrushtool4. SpotHealingBrushtool5. BurnorDodgetool
SectionIII:Creativetechniqueswithfilters
WhatphotoeditingprogramshouldIuse?AdobePhotoshopistheleadinggraphicseditingprogramusedbyprofessionalsandseriousamateurs.Itiscomplexandexpensive,butverypowerful.Therearemanyalternativeswithscaleddownfeaturesandprices,andsomeareevenfree.Examplesofconsumer‐levelproductsincludeAdobePhotoshopElements($70.00viaUCSDBookstore),GooglePicassa(free).Therearealsoagrowingnumberofonlineeditors.CNET.comrecentlyreviewed15popularproducts(http://cnet.com).
Whatisthebestwaytomanagedigitalimagecollections?Manyoftheconsumerlevelphoto‐editingprogramsalsoprovidetoolsforbrowsing,sorting,andapplyingkeywordsanddescriptions.InadditiontoPhotoshopElementsandPicassacitedabove,thereisiPhoto(Mac),WindowsLivePhotoGallery(Win),CorelMediaOnePlus(Win),Shoebox(Mac),andmanymore.
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Digitalimageeditingissometimesreferredtoas“post‐processing”orworkinginthe“digitaldarkroom”.Togetthebestresults,mostexpertsdescribeaspecific“workflow”oralogicalorderofsteps.ThedirectionsthatfollowassumeyouareworkingwithAdobePhotoshop,howeversimilarprocessesmaybeaccomplishedwithotherimageeditingprograms.
I.BASICIMAGEEDITINGPROCESS(makingglobalchangestotheimage):
1. Open:FromtheFilepulldownmenu:chooseOpenandselectthephototobeedited.
2. Createacopyforediting:FromtheFilepulldownmenu:chooseSaveAs.
Thedialogbox(left)willappear.a. IntheFileName(Mac:SaveAs)field(redarrow):
changetheimagenametoindicatethatthisistheeditedversion.Forexample,append“copy,”“_ed”or“_edit”totheendoftheoriginalfilename.
b. FromtheFormatpulldownmenu(bluearrow):selectPhotoshop.
c. SelectyourdestinationfolderandclickSave.
3. Rotate:Ifyourphotoishorizontalwhenitshouldbevertical?Orverticalinsteadofhorizontal?Orupsidedown?Hereiswhattodo:a. FromtheImagepulldownmenu:click+holdonRotate
Canvas(redarrow);asubmenuwillappear(bluearrow).
b. Selectappropriateaction:900CW,900CCW,or1800.c. Savethesechanges.
4. Adjustbrightnessandcontrast:Thetechniqueslistedbelowstartwiththesimplestandmovetothemorecomplex.Trythemintheorderinwhichtheyarelisted–onlymovingtothenextIFyouarenotsatisfiedwiththeresults.
ThesetechniquesarefoundintheImagepulldownmenuunderAdjustments(redarrow).Alladjustmentscoveredherearefoundintheupperportionofthesubmenu(withinbluebox).a. AutoLevels:theeasiestoptionthatsometimesworks
fine.Iftheresultisnotsatisfactory,selectUndo(Editmenu)orclickonthepreviousstepintheHistoryPalette,andmoveontothenextoption.
b. AutoContrast:Itworksontheoverallbrightnessandcontrast,butdoesnotalterthecolorsinthephoto.Again,UndoorusetheHistoryPaletteandmoveontothenextoptionifyoustillarenotsatisfied.
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c. Levels:ApowerfultoolalsofoundintheImagemenuunderAdjustments.TheLevelshistogramdisplaysthenumberofpixels(ontheyaxis)vs.thecolorofthepixels(onthexaxis)fromblack(0)towhite(255).
Mostphotoslookbestwhenthefullcolorrangeisusedandthehistogramspansfromblack(0)towhite(255).Ifblacksandwhitesaremissing,theimagemaylookflatandwashedout.
Ontheotherhand,sometimesimagestakenonarainyorfoggydayactuallydonothavethefullyblackorwhiteregionsofthehistogram.Soalwaysconsideryourpictureandhowyouwantittolook,whenmakingtheseadjustments.
UsingtheInputlevelsliders,youcanchangebrightness,contrast,andtonalrangebypickingwhatiscompletelyblack,completelywhite,andmiddlegray.
TherearetwowaystomodifyimageLevels:
SlidersbelowInputHistogram:• BlackPointslider(redarrow)• WhitePointslider(bluearrow)• Midtoneslider(yellowarrow)
EyeDroppers• BlackPointeyedropper(redarrow)• WhitePointeyedropper(bluearrow)• Midtoneeyedropper(yellowarrow)
♪NOTE:InLevelsandmanyoftheothertools,thereisawaytoResetyourchangesandstartoverwithoutleavingthedialogbox.
• PC:clickandholdthealtkey.• Mac:clickandholdtheoptionkey
TheCancelbuttonchangestoReset(redarrow).ClicktheResetbuttonandcontinuetoexperimentwithlevelsuntilyougetthebestpossibleeffect.
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5. AdjustColorBalance:Again,thestepslistedbelowstartwiththesimplesttechniqueandmovetothemorecomplex.Trythemintheorderinwhichtheyarelisted–onlymovingdownifyouarenotsatisfiedwiththeresults.Alltools/techniquesarefoundintheImagemenuunderAdjustments.
a. AutoColor:Thisistheveryeasiestoptionanditsometimesworksfine,especiallywhenyouhaveagoodmixofcolorsinyourphoto.Iftheresultisnotsatisfactory,selectUndo(Editmenu)orclickonthepreviousstepintheHistoryPalette,andmoveontothenextoption.
b. ColorBalancecanbeusedtomakesubtlechangesinthecolorofyourphotos.Itonlytakesasmallchangetocreatealargeeffectinyourimage.Becarefulnottooverdoandcreateunrealisticresults.
• Adjustcolorlevelsusingsliders(redbracket).
• Typically,workwithMidtonesselectedintheToneBalancebox(yellowbox).
• PreserveLuminosityshouldbechecked(bluebox)oryourpicturewillgetdarkerorlighterasyouchangecolors.
6. Crop:TheCroptool(locatedinthetoolbar,seeredarrow)allowsyoutoselectaportionofyourphotoanddeleteeverythingoutsidethearea.
a. Selecttheportionofthepictureyouwanttoretainb. Modifythearea,asneeded,byusingthehandlesonthesideoftheselection
box.
c. HitEnterandyourpictureswillbecropped.
Ifyouchangeyourmind,rememberyoucanalwaysselectUndo(Editmenu)orclickonthepreviousstepintheHistoryPalette,andmoveontothenextoption.
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7. Resize:Youmaywanttochangethesizeorresolutionofyourphotodependingontheintendeduse.
• Trytoresizeonlyonetime,asrepeatedresizingtendstoaddblurrinesstoyourpicture.
• Makeofcopyofthefull‐sized,editedimage(preferablyinPhotoshopformat)beforeyouchangeimagesize,resolution,orfiletype.Thiswillenableyoutogobackatalatertimeandmakecopiesforotherpurposes.
a. FromImagepulldownmenu,selectImageSize(redarrow).
b. TheImageSizedialogboxprovidesameanstomanipulatemultiplevariables:
PixelDimensions(redbox)andDocumentSize(greenbox)arelinked;changingoneaffectstheotherANDthefilesize(redarrow).
Resolution(bluebox)canbeindependentlychanged.Seediscussionbelowaboutwhatresolutiontoselect.
ConstrainProportions(greenarrow)shouldbecheckedtoensureheighttowidthratioaremaintained.Aninterpolationalgorithm(bluearrow)shouldbeselectedaccordingtowhetheryouareincreasingordecreasingimagesize.
• Foruseinemailortheweb:Remembersmallerfilesizesloadfasterandareeasiertosendviaemail.Twocomponentscontributetofilesize,resolution&imagesize.Oldercomputermonitorshavearesolutionof72dpiwhilenewermonitorshavearesolutionof96dpi.Ifyourimagehasahigherresolutionitwillnottranslatetoahigherviewqualityoncomputermonitors.
‐ IftheoptionResampleImageisselected(lookjustbelowthegreenarrow),theimagesizewilldecreasewhenyoureducetheResolution.
‐ ToadjusttheResolutionofyourimagewithoutaffectingtheimagesize,unchecktheResampleImageoption.
• Foruseinprinting:Youshouldusearesolutionatleastequaltothedotsperinch(DPI)ofyourprinter,butusingmoreusuallyproducesabetterresult.
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8. Sharpen:ThesharpeningprocessshouldonlybedoneAFTERallotherstepsofphotoediting.Regardlessofthemethodused,DONOTOVERSHARPEN.Itwillinducenewartifactsandshiftsintheimagecolors.Herearetwomethods,easiestfirst.
a. Sharpen:FromtheFilterspulldownmenu,selecttheSharpenmenu(redarrow)andthenselecttheSharpenfilter(greenarrow).Thisactionwillsetadefaultpercentagetoyourimage.Itisaquickfixandsometimesworks.
b. UnsharpMask:FromtheFilterspulldownmenu,selecttheSharpenmenu(redarrow)andthenselecttheUnsharpMask...(yellowarrow).Thisiseffectivelyahigh‐passfilterthatdetectsedgesandaddscontrastalongtheedges.
TherearethreesettinginUnsharpMask.Whilethereisnoclearconsensusontheorderandvalueforeachsetting,Iusetheminthefollowingorderandselecteffectsthatlookgoodonthepreviewwindowat100%.
i. Radiussetting(redarrow)establishesthesizeofthesharpeningeffectalongeachperceived“edge”.
OnegenerallystartswiththeRadiusaround1.0‐1.5pixels.
• Forphotoswithalotoffinedetail,lowertheRadiussettingto0.5‐1.0.
• Forphotoswithlessdetail,raisetheRadiusto2.0‐4.0
ii. Amountsetting(greenarrow)dictatesthestrengthofthesharpeningbydetermininghowmuchcontrastisaddedattheedges.
• WithasmallRadius,uselargerAmount.• WithalargeRadius,useasmallerAmountofsharpening.Therearenospecific
numberstorecommend.
iii. Thresholdcontrol(yellowarrow)isbasicallyanoise‐reductionsetting.IttellsPhotoshoptoignoreacertainamountofdifferencesbetweenpixelswhensharpeningbysettingtheminimumbrightnesschangethatwillbesharpened.Itenablesyoutoavoidoversharpeninglightlytexturedareas,whilestillsharpeningmorepronouncededgesandleavingmoresubtleedgesuntouched.OnceRadiusandAmountareset,decreaseThresholduntilunwantednoiseandotherartifactsappear,thenraiseitslightly.
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SaveAs:Nowisthetimetoselectafiletypeforyourpicture.Theoneyouchoosewilldependonhowyouintendtousetheimage.
Listedbelowarethemostfrequentlyusedgraphicfileformatsandtheirextensions:
a. PSD–default(“native”)fileformatforAdobePhotoshop.Sinceitpreservesalloftheeditingcapability(e.g.,layers,transparency,etc.),itisgoodpracticetokeepaPSDversionofyouroriginalfileandanotheroftheeditedforsubsequenteditsandadjustments.
b. JPG–theformatdevelopedbytheJointPhotographicExpertsGroup.Itisacross‐platformfileformat(MacandPC)primarilyusedforwebandMicrosoftPowerPointapplications.JPEGisbestforphotoswhenyouwanttokeepthefilesizesmall(withonlysomelossinquality).WheneveraJPGfileisclosed,thefileiscompressed.Therefore,youreditingshouldbedoneonthePSDfileifpossibleandthensavedasaJPG.MultiplesavesofaJPGimagedegradeimagequality.
c. TIFF–TaggedImageFileformat.Across‐platformfileformatprimarilyusedforprintingapplications.Itproduceslargefileswithnolossinquality.
SectionII:Techniquesthataddressspecificproblems/needs
Correctingflawsistypicallydoneafterlevel,brightness/contrast,andcolorcorrectioniscompleted,butbeforeyoucroporsharpentheimage..
1. Dust&Scratchesfilteristheeasiest,butmostprimitivesolutionbecauseitcandegradeyourimage.Itworksbestiftheproblemarealacksalotofdetailandwhenpossibletheareawithdustorscratchesisselected.
a. TofindtheDust&Scratchesfilter:i. GototheFilterpulldownmenu(redarrow)
ii. ClickandholdontheNoisecategory(yellowarrow)iii. SelectDust&Scratchesfromthesubmenu.
b. Dust&Scratchesdialogbox:
i. SetThresholdtozero(redarrow)ii. DragtheRadiusslider(greenarrow)untilthedustor
scratchesgoesaway.
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2. CloneStamptoolcanbeusedtoremoveeverythingfromsmalldustmarkstolargeunwantedobjectsfromyourphoto.Itisaretouchingtoolthatletsyoucopy(sampleorclone)pixelsfromoneareaandthenpastethemontoanotherarea.Forexample,toremoveadustspotintheskyofyourpicture,youwouldsamplethepixelsinanadjacentclearpartofthesky,andthenusethosepixelstocoverthedustspot.
a. SelecttheCloneStampToolfromthetoolbox(bluearrow).BesureyouhaveselectedCloneStampandnotPatternStamp.
b. Yourbrushsizeandshapedepends(inpart)onthesizeoftheflawyouaretryingtocorrect.Tochooseabrush:
• ClickthetinyarrowtotherightofthebrushiconontheCloneStampOptionsBar(attopofthescreen,belowtheMenuBar)Orright‐clickonthephototobringupthebrushsettingsdropdownmenu.
• Masterdiametersetting(redarrow)o Tocorrectminorproblems,useabrush
diameterthatisslightlylargerthantheflawyouwanttocorrect.
o Toremovelargeunwantedobjects,useasmallbrush(5‐10pixels)andsamplefrommanysourcestoblendthepatch.
• Hardnesssetting(greenarrow)o Tomakeprecisesamplesofyoursource
pixels,itisbettertouseaveryhardbrush(~100%).
♪NOTE: Onceyouhaveabrushselected,youcaneasilyrefineitsdiameterwhilethebrushsitsovertheareayouwishtopaint.Theleftbracket[makesthebrushsmaller,whiletherightbracket]‐‐makesthebrushbigger.Thisshortcutworkswithanytoolthathasabrush.
c. Thecloningprocess:• Movethecursorovertheareaofthepicturetobecloned(the“sample”).
• DepresstheAlt(Mac:Option)key.Thecursorwillchangetoatarget.Nowclickthemousetomarkfromwherethepixelswillbesampled.
• Moveyourbrushovertheareayouwanttorepair.Clickandpaintoverthearea.Noticethatthepointfromwhichyousampled(markedbyacrosshair)moveswithyourbrushasyoupaint.
• Repeatthelasttwostepsasneeded.
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♪NOTE: Zoom(magnify)theareaofinteresttomoreeasilyworkwiththeCloneStampandothertools.Tomagnifyanimageyouhaveseveraloptions:
1. Usethezoomsliderinthenavigatorpalette.
2. Typingalargernumberinthe%magnificationboxofthenavigatorpaletteorthestatusbar.
3. Selectthemagnifyingglassfromthetoolbar.Thenclickontheimage.A+signwillappearinsidethemagnifyingglass.Eachtimeyouclickthetoolontheimage,themagnificationwillincrease.
4. UsetheshortcutCtrl+plussign(PC)orCmd+plussign(Mac).Eachtimeyouusetheshortcut,themagnificationwillincrease.
♪NOTE: Todemagnifyanimageyouhaveseveraloptions:
‐ Usethezoomsliderinthenavigatorpalette.
‐ Typeasmallernumberinany%magnificationbox.
‐ Holddownthealtkeywhileusingthemagnifyingglassmakesitworkinreverseanda‐(negativesign)showsupinsidetheglass.Eachtimeyouclickthetoolontheimage,themagnificationwilldecrease.
‐ UsetheshortcutCtrl+minussign(PC)orCmd+minussign(Mac).Eachtimeyouusetheshortcut,themagnificationwilldecrease.
3. TheHealingBrushtoolworksalotliketheCloneStamptool.Butinsteadofcoveringtheimperfectionswithacopyofsampledpixels,theHealingBrushblendsthesampledpixelsintotheimperfectionssuchasscratches,blemishes,etc.
a. ClickontheHealingBrushiconinthetoolboxandselecttheHealingBrush
b. Checkthesettingsintheoptionbar,includingbrushdiameterandblendingmode.Sourceshouldbe“sampledfromtheimage”
c. Alt‐click(Mac:Option‐click)neartheimperfectiontodefinethestartingpointofthesample.
d. Paintovertheimperfection.Ifalignedisselected,theHealingBrushtoolwillrememberthestartingpointbetweenmouseclicks.
4. TheSpotHealingBrushtoolisgreatifyouonlyneedtofixsmallimperfections(likeaspotordustmarkinthesky.Thistooldoesnotrequireasourcetobespecified.Insteaditautomaticallysamplestheadjacentpixelsanddabsawaytheproblem.
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5. TheRedEyetoolisfoundinthesametoolbarboxastheHealingBrush.Selectthetoolandclickoneacheye.Itdoesnotalwayswork,butitistheeasiestoptiontotry.
6. TheBurnorDodgetoolcanbeusedtochangetheexposureofaspecificallydefinedarea.Thenamesofthesetoolscomefrompre‐digitaldarkroomtechniqueswherelightcouldbeblockedout(dodged)fromapartoftheimagetolightenorlightcouldbeconcentratedtodarken(burn)anarea.a. Dodge(yellowarrow)lightenspixels
Burn(greenpixels)darkenspixels.
b. BeginwiththetoolsettoMidtones.Pickawide,soft‐edgedbrush.UsealowExposuresetting(10‐15%),sincelowerthesetting,thelessdrastictheeffect.
c. Thesetoolsworkbestongrayscaleimages.Withcolorimages,usethesetoolssparinglyortheresultscanbeunnatural.
♪ NOTE: TheSpongeTool,notcoveredinthisworkshop,canbeusedtoincreaseordecreasethecolorsaturation.
PartIII.CreativeTechniqueswiththeFilterGallery
1. TheFilterGalleryisfoundintheFiltersmenu.Whenitopens,theworkareadividedinto3panels:
a. Theimageisseenontheleftside(redbox).Youcanchangethemagnificationclickingonthe‐+orbyselectinga%magnificationfromthecontrolsatthebottomleftofthepicture(redarrow).
b. Thefilterselectionisshowninthemiddlepanel(greenbox).Itisdisplayedbycategoriesthatcanbeexpandedbyclickingontherightpointingarrow.
c. Withafilterselected,usethesliderscontrols(bluebox)tochangespecificcharacteristicsoftheselectedfilter.
2. Multiplefilterscanbeappliedtothesameimage.Theyappearinalist(bluearrow)thatworksjustlikethestandardPhotoshoplayers.Itnamesthefilterselectedandhasaneyeicontoshowthatitisvisible.Youcanclickonthepageiconatthebottomofthisboxandcreateanewlayerthatcanbeusedforanotherfilter.Youcanapplyasmanyfiltersasyoulikeandchangetheorderbydraggingthelayerupanddown.
3. Ifyouknowexactlywhatfilteryouwanttoapply,youcanselectiffromthelist.TheFilterGallerywillthenopenwithyourchosenfilterselectedandapplied.
