A Colorimetric Analysis A Colorimetric Analysis Methodology forMethodology forPhilatelic StudiesPhilatelic Studies
Prepared for Stampshow 2010David L. Herendeen
12 August 2010
22
200,010,010 200,020,10 200,010,010
33
230,250,090 230,235,90 220,240,085
44
200,010,010 200,010,010 200,020,010
55
What Color Are These 1851 Stamps ?
Bright Orange BrownRose Brown
Intense Orange Brown
Dull RedDull Claret
Pale Orange Brown
MoroccoDull Red
Rose Brown
Reddish Orange Brown
Deep Orange BrownDull Claret
Courtesy National Postal Museum
66
What Color Are These 1851 Stamps ?
Bright Orange BrownRose Brown
Intense Orange Brown
Dull RedDull Claret
Pale Orange Brown
MoroccoDull Red
Rose Brown
Reddish Orange Brown
Deep Orange BrownDull Claret
Courtesy National Postal Museum
Color is not so EasyColor is not so Easy
IS IT ??IS IT ??
88
Talking PointsTalking Points
Some backgroundSome background What we plannedWhat we planned What we didWhat we did What we learnedWhat we learned What’s next?What’s next? NPM Support NPM Support
...A Retrospective...A Retrospective
99
BackgroundBackground
What is color?What is color? What is colorimetryWhat is colorimetry Spectroscopy and the VSC Spectroscopy and the VSC
60006000 How are colors measured?How are colors measured? Commission International Commission International
de l’Eclairage (CIE)de l’Eclairage (CIE)
1010
BackgroundBackground
MeasureReflectance
orAbsorption
of Light
CIE Color Models
1111
What we plannedWhat we planned
Use the NPM VSC 6000 to perform Use the NPM VSC 6000 to perform colorimetric analysiscolorimetric analysis
Understand colorimetry in the philatelic Understand colorimetry in the philatelic contextcontext
Understand the scientific measurement Understand the scientific measurement of color and its relationship to stampsof color and its relationship to stamps
Determine if scanning can be used as a Determine if scanning can be used as a cost-effective substitute for cost-effective substitute for spectroscopyspectroscopy
1212
What we didWhat we did
Analyzed hundreds of Slovenian Analyzed hundreds of Slovenian postage due stamps of 1919-21postage due stamps of 1919-21
Recorded results and reduced dataRecorded results and reduced data Correlated spectroscopic results Correlated spectroscopic results
with human color expertwith human color expert Developed interpolation model for Developed interpolation model for
use with scannersuse with scanners
1313
Sampling the stampsSampling the stamps
…What we did
1414
Sampling the stampsSampling the stamps
…What we did
1515
Sampling the stampsSampling the stamps
…What we did
1616
Processing the resultsProcessing the results
…What we did
70 Sample Points - Ljubljana
0.480
0.485
0.490
0.495
0.500
0.505
0.510
0.310 0.320 0.330 0.340 0.350 0.360 0.370 0.380 0.390
u' (1976 CIE)
v' (
1976
CIE
)
1717
Processing the resultsProcessing the results
…What we did
1818
Comparison by expertComparison by expert
…What we did
1919
Color categoriesColor categories
…What we did
70 Sample Points - Ljubljana
0.480
0.485
0.490
0.495
0.500
0.505
0.510
0.310 0.320 0.330 0.340 0.350 0.360 0.370 0.380 0.390
u' (1976 CIE)
v' (
1976
CIE
)
2020
Color categoriesColor categories
…What we did
70 Sample Points - Ljubljana
0.480
0.485
0.490
0.495
0.500
0.505
0.510
0.310 0.320 0.330 0.340 0.350 0.360 0.370 0.380 0.390
u' (1976 CIE)
v' (
1976
CIE
)
2121
Categories Defined by Color Expert
0.480
0.485
0.490
0.495
0.500
0.505
0.510
0.310 0.320 0.330 0.340 0.350 0.360 0.370 0.380 0.390
u' (1976 CIE)
v' (
1976
CIE
)
Color categoriesColor categories
…What we did
Brick Red
2222
Categories Defined by Color Expert
0.480
0.485
0.490
0.495
0.500
0.505
0.510
0.310 0.320 0.330 0.340 0.350 0.360 0.370 0.380 0.390
u' (1976 CIE)
v' (
1976
CIE
)
Color categoriesColor categories
…What we did
Deep brownish carmine
Brick Red
2323
Categories Defined by Color Expert
0.480
0.485
0.490
0.495
0.500
0.505
0.510
0.310 0.320 0.330 0.340 0.350 0.360 0.370 0.380 0.390
u' (1976 CIE)
v' (
1976
CIE
)
Color categoriesColor categories
…What we did
Deep brownish carmine
RedBrick Red
2424
Categories Defined by Color Expert
0.480
0.485
0.490
0.495
0.500
0.505
0.510
0.310 0.320 0.330 0.340 0.350 0.360 0.370 0.380 0.390
u' (1976 CIE)
v' (
1976
CIE
)
Color categoriesColor categories
…What we did
Deep brownish carmine
Red
Carmine
Brick Red
2525
Categories are “Fuzzy”Categories are “Fuzzy”
…What we did
"Fuzzy" Color Categories
0.480
0.485
0.490
0.495
0.500
0.505
0.510
0.310 0.320 0.330 0.340 0.350 0.360 0.370 0.380 0.390
u' (1976 CIE)
v' (
1976
CIE
)
2626
Categories are “Fuzzy”Categories are “Fuzzy”
…What we did
Blow-up of Fuzzy Envelopes for Shades 2 and 3
0.490
0.492
0.494
0.496
0.498
0.500
0.502
0.504
0.506
0.508
0.510
0.320 0.325 0.330 0.335 0.340 0.345 0.350 0.355 0.360 0.365 0.370
u' (1976 CIE)
v' (
1976
CIE
)
1.00
0.84
0.40
0.17
0.14
Fuzzy WeightingFunction
2727
Theoretical Theoretical developmentdevelopment
…What we did
Formulated a method for defining Formulated a method for defining color categoriescolor categories
Created a model for understanding Created a model for understanding how individual perception can affect how individual perception can affect philatelic color identificationphilatelic color identification
Correlated this model to “real” test Correlated this model to “real” test datadata
Formed a building block for future Formed a building block for future philatelic color researchphilatelic color research
2828
Using a scannerUsing a scanner
…What we did
Spectroscope forTristimulus Values
(X,Y,Z)
CalibrateYour Scanner
(R,G,B)
Unknown Sample(Ru,Gu,Bu)
3D InterpolationFunction
Maps to:(Xu,Yu,Zu)
u’,v’Categories Defined by Color Expert
0.480
0.485
0.490
0.495
0.500
0.505
0.510
0.310 0.320 0.330 0.340 0.350 0.360 0.370 0.380 0.390
u' (1976 CIE)
v' (
1976
CIE
)
2929
What we learnedWhat we learned
How to apply the VSC 6000 for How to apply the VSC 6000 for colorimetrycolorimetry
Philatelic color is NOT a matching Philatelic color is NOT a matching problem, it is about categorizationproblem, it is about categorization
Colorimetry is faster and cheaper than Colorimetry is faster and cheaper than x-ray spectroscopy methodsx-ray spectroscopy methods
Scanners can be used to identify colors Scanners can be used to identify colors IF preliminary analysis has been IF preliminary analysis has been performedperformed
3030
What’s next?What’s next?
Completing the scanner Completing the scanner mappingmapping
Documenting and publishing Documenting and publishing all resultsall results
Extending the methodology to Extending the methodology to new projectsnew projects
3131
Two papers:Two papers:– Philatelic Shade Discrimination BasedPhilatelic Shade Discrimination Based
on Measured Color (Herendeen, Allen on Measured Color (Herendeen, Allen and Lera)and Lera)
Color Research and Applications Color Research and Applications and/orand/or London PhilatelistLondon Philatelist
– Using a Scanner to Determine Stamp Using a Scanner to Determine Stamp Shades (Herendeen, Allen and Lera)Shades (Herendeen, Allen and Lera)
London Philatelist London Philatelist oror Collectors Club Collectors Club PhilatelistPhilatelist
Documenting the workDocumenting the work
…What’s next?
3232
NPM SupportNPM Support
Value of NPM scholarship Value of NPM scholarship programprogram
Leveraging human resourcesLeveraging human resources Incubator for IAPIncubator for IAP
3333
AcknowledgementsAcknowledgements
Mr. Allen KaneMr. Allen Kane– For his vision of extending the services of For his vision of extending the services of
the NPM to the philatelic worldthe NPM to the philatelic world Mr. Thomas Lera, Winton Blount Chair Mr. Thomas Lera, Winton Blount Chair
of Research, NPMof Research, NPM– For his continual support and assistance For his continual support and assistance
with all aspects of this effortwith all aspects of this effort Mr. James Allen, Senior Fellow, IAPMr. James Allen, Senior Fellow, IAP
– For his long hours sorting and categorizing For his long hours sorting and categorizing Slovenian postage duesSlovenian postage dues
The EndThe End