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MinH.Kim(KAIST) CS681:ComputationalColorimetry
CS681ComputationalColorimetry
MinH.KimKAISTSchoolofComputing
MinH.Kim(KAIST) CS681:ComputationalColorimetry
INTRODUCTIONAboutCS681ComputationalColorimetry
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MinH.Kim(KAIST) CS681:ComputationalColorimetry
Courseinformation:CS681• Subject:ComputationalColorimetry• Date:TuesdayandThursday• Time:10:30AM—11:45PM• Place:Rm.3444,Bldg.E3-1
MinH.Kim(KAIST) CS681:ComputationalColorimetry
AboutInstructor• Dr.MinHyukKim(김민혁)
– ProfessoratKAISTSchoolofComputing– ResearcheratYaleUniversity– PhDinComputerScience(UCL2010)– AssociateeditorofACMTOG(TopCSJournal)&ACMTAP– ProgramcommitteeofACMSIGGRAPHAsia,Eurographics,etc.– MicrosoftNewFacultyAward&Naver YoungFacultyFellowship– BestPaperAwards(ACCV,VAST)
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MinH.Kim(KAIST) CS681:ComputationalColorimetry
AboutInstructor
• Office:Rm.3429,Bldg.E3-1• Officehours:TuesdayandThursday16:00—17:00(pleaseletmeknowinadvance)
• E-mail:minhkim@vclab.kaist.ac.kr
MinH.Kim(KAIST) CS681:ComputationalColorimetry
AboutTeachingAssistant
• TeachingAssistant:Giljoo Nam,PhDstudentatVCLAB
• Office:Rm.3422,Bldg.E3-1• Email:gjnam@vclab.kaist.ac.kr
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MinH.Kim(KAIST) CS681:ComputationalColorimetry
Courseinformation:CS681
• 3-creditcourse• Yourgradewillbecalculatedby:– Classparticipation:10%–Midterm/finalexams:50%– Assignments:30%– Classquizzes(atthebeginningoflectures):10%
MinH.Kim(KAIST) CS681:ComputationalColorimetry
CourseWebsite• http://vclab.kaist.ac.kr/cs681/
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MinH.Kim(KAIST) CS681:ComputationalColorimetry
Textbook• RoyS.Berns (2000)PrinciplesofColorTechnology,3rdEd.,JohnWiley&Sons,Inc.
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MinH.Kim(KAIST) CS681:ComputationalColorimetry
References
• TheReproductionofColour,6thEd.,R.W.G.Hunt(2004)
• MeasuringColour,4st Ed.,R.W.GHunt,M.R.Pointer(2011)
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MinH.Kim(KAIST) CS681:ComputationalColorimetry
References
• ColorAppearanceModels,2nd
Ed.,Fairchild(2005)
• Colorimetry,1st Ed.,Ohta andRobertson(2005)
MinH.Kim(KAIST) CS681:ComputationalColorimetry
References
• ColorImaging,1st Ed.,Reinhardetal.(2008)
• HighDynamicRangeImaging,2nd Ed.,Reinhard etal.(2010)
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MinH.Kim(KAIST) CS681:ComputationalColorimetry
References
• DigitalModelingofMaterialAppearance,1st Ed.,Dorseyetal.(2008)
MinH.Kim(KAIST) CS681:ComputationalColorimetry
Objectives:CS681• Learnfundamentalsabout…– Theoreticalbackgroundaboutcolor– Advanceddigitalcolorimaging(advancedtechniquesbyusingadigitalcameraandcomputerdisplay)
– Latestcomputationalapplicationsaboutcolor
• Homeworkaboutcolorimageprocessing
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MinH.Kim(KAIST) CS681:ComputationalColorimetry
TentativeSyllabus
MinH.Kim(KAIST) CS681:ComputationalColorimetry
INTRODUCTION
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MinH.Kim(KAIST) CS681:ComputationalColorimetry
IntroductiontoResearchAreas
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MinH.Kim(KAIST) CS681:ComputationalColorimetry
COLOR(1)
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MinH.Kim(KAIST) CS681:ComputationalColorimetry
Color• Wehavebeenusingr,g,b…• Why?• Whatisacolor?• Canwegetallcolorsthisway?• Howdoeswavelengthfitinhere,whatpartisphysics,whatpartisphysiology.
• CanIuser,g,bforsimulationofreflection?• Howshouldcolorsbestored.
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MinH.Kim(KAIST) CS681:ComputationalColorimetry
Differentmeaningsofcolor• Neuralresponseofconecells:retinalcolor• Thisisprocessedgivingus:perceivedcolorthatweactuallyexperienceandbasejudgmentsupon.– Notewedonothavedirectexperientialaccesstoretinalcolor
• Theperceivedcolorisoftenassociatedwiththeobject.Weareobserving,whichwemightcalltheobjectcolor.
• Weorganizecolorsandnamethemaswell.20
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MinH.Kim(KAIST) CS681:ComputationalColorimetry
Color• Humanvisualsystemtransformsradiationintosensation
Vis
ible
Lig
ht
700 n
m600 n
m500 n
m400 n
m
red
Ora
ng
eyello
wg
reen
blu
ein
dig
ovio
let
Perceptualresponse
Sensibleonly380~780nm
Physicalstimuli
Electromagneticradiation
Colorexistsonlyinourbrain!
MinH.Kim(KAIST) CS681:ComputationalColorimetry
Newton’sExperiment
Newton’sbirthplace(1642)atWoolsthorpe Manor,Lincolnshire
UsingaprismtoproduceaspectrumCambridgeTrinityCollege,1665
Firstscientificdiscoveryofcolor
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MinH.Kim(KAIST) CS681:ComputationalColorimetry
Newton’sApparatus
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Light is a mixture of differently refrangible rays- Isaac Newton, Opticks
Hole
LensPrismScreenHole
Narrow-bandcolor
MinH.Kim(KAIST) CS681:ComputationalColorimetry
Visible?Invisiblespectrum?
• Visiblelight:400-700nm• Barely one octave out of
40 is visible to the eye
• Invisiblelight:– X-ray:1nm– Microwave:1cm– Radar:10cm– UHF,VHF,FMradio:1-10m– AMradio:100-1000m
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MinH.Kim(KAIST) CS681:ComputationalColorimetry
Definitionofspectralregions
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MinH.Kim(KAIST) CS681:ComputationalColorimetry
MeasuringColor
• Solid-statearray-basedsystem• Dispersiveelement:eitherprismordiffractiongrating
• Theonethatwetriedlasttime
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MinH.Kim(KAIST) CS681:ComputationalColorimetry
Lightbeams• Visiblelightiselectromagneticradiationthatfallsroughlyinthewavelengthsof380<λ <770,measuredinnanometers.
• Apurebeamlλ hasone“unit”oflightofaspecificwavelength λ.
• Amixedbeaml(λ) hasdifferentamountsofvariouswavelengths.– Theseamountsaredeterminedbythefunction
– Thevalueisalwaysnon-negativesincethereisno“negativelight”.
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l(⋅) :R→ R+
MinH.Kim(KAIST) CS681:ComputationalColorimetry
ComputingReflectancefromRadiance
• Radiance:energyperunitareapersolidangle• Reflectance:energyatspecifiedangle,relativetoenergy
reflectedbyperfectdiffuser• Foraconstantly-illuminatedsurface,thereflectanceatagiven
angleisgivenby:
• Sincetheradianceofaperfectdiffuserisnotknown,itcanbefoundbymeasuringtheradiancereflectedonacalibrationtilewithknownreflectance(whitetile,so-calledSpectralon).
R(λ)sample =I(λ)sampleI(λ)reference
I(λ)reference =I(λ)calibrationR(λ)calibration
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MinH.Kim(KAIST) CS681:ComputationalColorimetry
Light
Spectralradiation
Spectralreflectance
Spectralreflection
Observer
MinH.Kim(KAIST) CS681:ComputationalColorimetry
Light
Spectralradiation
Spectralreflectance
Spectralreflection
Observer
ObserverResponse
( )P l
( )r l
( ) ( )P l r l
( )V l
( ) ( ) ( )V Pl l r l( ) : Visual response( ) : Object spectrum( ) : Illumination spectrum
V
P
lr ll