the effect of gray balance and tone reproduction on consistent color appearance · 2017-01-23 ·...
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TheEffectofGrayBalanceandToneReproductiononConsistentColorAppearance
Nov.28,2016
ElenaFederovskayaandBobChung,RIT
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Introduction
• CMYKimagefiles,whenoutputtoISO15339-2CRPCs,aresaidtohaveconsistentorcommoncolorappearance(CCA)despitetheircolorimetricdifferencesinwhitepointandgamutvolume.• CIEDivision8(ImageTechnology)proposedthestudyof“ConsistentColorAppearance(CCA)”in2016.• Thisprojectexplorestheeffectofgraybalanceandtonereproductionasunderlyingcriteriaofconsistentcolorappearance.
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TheoreticalBasis
• ISO15339-2CRPCs
CRPC CRPC name1 ColdsetNews2 HeatsetNews3 PremUncoated4 SuperCal5 PubCoated6 PremCoated7 Extra Large
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TheoreticalBasis• GamutvolumecomparisonofCRPCsinColorThinkPro3
L* a* b* L* a* b* L* a* b* L* a* b* L* a* b*CRPC1 85 1 5 59 -24 -26 56 48 0 80 -2 60 37 1 4 84,280CRPC2 87 0 3 57 -28 -34 52 58 -2 82 -2 72 30 1 2 151,311∆EabCRPC2 87 0 3 57 -28 -34 52 58 -2 82 -2 72 30 1 2 151,311CRPC3 95 1 -4 60 -26 -44 56 61 -2 89 -3 76 32 1 1 165,764∆EabCRPC3 95 1 -4 60 -26 -44 56 61 -2 89 -3 76 32 1 1 165,764CRPC4 89 0 3 55 -36 -38 47 66 -3 83 -3 83 23 1 2 253,711∆EabCRPC4 89 0 3 55 -36 -38 47 66 -3 83 -3 83 23 1 2 253,711CRPC5 92 0 0 57 -37 -44 48 71 -4 87 -4 88 19 0 1 331,416∆EabCRPC5 92 0 0 57 -37 -44 48 71 -4 87 -4 88 19 0 1 331,416CRPC6 95 1 -4 56 -37 -50 48 75 -4 89 -4 93 16 0 0 389,023∆EabCRPC6 95 1 -4 56 -37 -50 48 75 -4 89 -4 93 16 0 0 389,023CRPC7 97 1 -4 54 -42 -54 47 78 -10 90 -4 103 14 0 0 525,551∆Eab
CRPC
2.0 6.7 6.8 10.0
4.2 6.4 5.2
9.2 9.1
2.0
5.1 6.1 4.0 5.4 3.2
10.7 10.6 5.0 8.1 2.2
6.5 4.2
9.3 12.7 10.3
Paper C100 M100 Y100 K100
3.0 9.2 11.0 12.2 7.3
17%
35%
GamutVolume
GamutVolumeDiff.
80%
10%
53%
31%
5TheoreticalBasis
• Greyreproductionrampspre-definedCMYtripletsareplottedwitha*rampsassolidlinesandb*rampsasdottedlinesinthesamecolorforeachCRPC.• AllCRPCsshowsimilarconvergingpatterns.
!5#
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0# 10# 20# 30# 40# 50# 60# 70# 80# 90# 100#
a*/b*%
%TV%
RPC1_a# RPC1_b# RPC3_a# RPC3_b#
RPC5_a# RPC5_b# RPC7_a# RPC7_b#
!5#
!4#
!3#
!2#
!1#
0#
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3#
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0# 10# 20# 30# 40# 50# 60# 70# 80# 90# 100#
a*/b*%
%TV%
RPC2_a# RPC2_b# RPC4_a#
RPC4_b# RPC6_a# RPC6_b#
CRPC1,3,5,and7 CRPC2,4,and6
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TheoreticalBasis
• Tonereproductioncurve(TRC)canbeexpressedbyplottingDarkness(100- L*)vs%TVofthecyan.• AllCRPCsshowsimilarhighlight-to-midtoneTRC.
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0" 10" 20" 30" 40" 50" 60" 70" 80" 90" 100"
Dk#
%TV#
RPC1_Dk"
RPC3_Dk"
RPC5_Dk"
RPC7_Dk"
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60.0"
70.0"
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0" 10" 20" 30" 40" 50" 60" 70" 80" 90" 100"
Dk#
%TV#
RPC2_Dk"
RPC4_Dk"
RPC6_Dk"
CRPC 1, 3, 5, and 7! CRPC 2, 4, and 6!
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PictorialSimulationofCRPC1~CRPC7(Chung)
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PictorialSimulationofCRPC1~CRPC7(Hutcheson)
81 2 3 4 5 6 7
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SignificanceofISO15339-2CRPCs
• Enabledevicecalibrationand“printingbynumbers”• ThereisalwaysasuitableCRPCtocalibratetheoutputdeviceto.
• Simplifyprepress• Colorimages,separatedforoneoftheCRPCs,canbeprintedinotherCRPCcalibratedprintingconditionsandpreservingconsistentcolorappearance.
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ProblemStatementandResearchQuestion
• Oneproblem• Thereisnorigorousstudythatgraybalanceandtonereproductionareindicativeofconsistentcolorappearance.
• Oneresearchquestion• Howtodeviseapsychometricexperiment,usingstandardCMYKtestimagesandminimumISO15339-2CRPCdatasets,toshowthatgraybalanceandtonereproductionareunderlyingcriteriaofconsistentcolorappearance?
Note:Tostudyconsistentcolorappearance,theminimumnumberofdatasetsis”3”wherethecolordifferencesbetweenthetwoadjacentdatasetsarethesame.
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ExperimentalProcedures1. CRPC5,6,and7arechosenbecausethe95thpercentileCRF∆E00
colorimetricdifferencesbetweenCRPC6andthetwoadjacentCRPCs(outergamut)aresimilar.
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CRF
∆E00
CRPC(1_2)CRPC(2_3)
CRPC(3_4) CRPC(4_5) CRPC(5_6) CRPC(6_7)
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ExperimentalProcedures
2. PreparetestimagesinCRPC5,6,and7conditionstodepictconsistentcolorappearance.
CRPC5CRPC6CRPC7
Scene1
Scene2
Scene3
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ExperimentalProcedures
3. AdjustgraybalanceandtonalreproductionofCRPC6testimages,includingtheIT8.7/4targetandtheP2P25target,suchthat95thpercentile∆E00 betweentheCRPC6andaltered-CRPC6datasetsisthesameasthe95thpercentile∆E00 betweenadjacentCRPCdatasets.
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ExperimentalProcedures4. Conductpsychometricexperimentsbyasking,“whichpictorialimageof
thesamescenelooksmoredifferentthantheotherthree,”duetoalteredgraybalanceandtonereproductioncharacteristics?
CRPC7
CRPC6
CRPC5
CRPC6altered
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ExperimentalProcedures
5. Wecanalsotest“whichpictorialscenelooksmoredifferentthantheotherthreescenes?”duetoalteredgraybalanceandtonereproductioncharacteristicsofaparticularCMYKimage.
Note:We’llneedmorethanthreepictorialscenestoaccomplishthisobjective.