Multispectral imaging and analysis of the Archimedes Palimpsest

82 Pages·2016·10.89 MB·English

by  D. Michael Hansen

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Theses
5-9-2006
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D. Michael Hansen
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School of Print Media
Rochester Institute of Technology
Rochester, New York
Certificate of Approval
Master's Thesis
This is to certify that the Master's Thesis of
D. Michael Hansen
has been approved by the Thesis Committee as satisfactory
for the thesis requirement for the Master of Science degree
at the convocation of
May 2006
Thesis Committee:
Franziska Frey
Primary Thesis Advisor
Roger L. Easton, Jr.
Secondary Thesis Advisor
Twyla J. Cummings
Graduate Program Coordinator
Twyla J. Cummings
Graduate Thesis Coordinator
Name Illegible
Chair, SPM
Multispectral Imaging andAnalysis ofthe
Archimedes Palimpsest
By
D. Michael Hansen
Athesis submitted inpartial fulfillmentofthe
requirements forthe degree ofMasterofScience inthe
School ofPrint Media inthe College
ofImagingArts and Sciences ofthe
Rochester Institute ofTechnology
May 9, 2006
Advisors:
Dr. Franziska Frey
Dr. RogerEaston, Jr.
Copyright Notice
Rochester Institute of Technology
School of Print Media
Title of Thesis:
Multispectral Imaging and Analysis of the Archimedes Palimpsest
All images of the Archimedes Palimpsest, unless otherwise noted, including those
produced for this research project, are copyrighted intellectual property of the owner
of the Archimedes Palimpsest. Images were produced by the Rochester Institute of
Technology and lohns Hopkins University and are used with permission. All images
may not be reproduced for any purpose in whole or in part without written permission.
All other images used in conjunction with this thesis research are used with permission.
D. Michael Hansen
Signature of Author
11
Acknowledgements
IwishtothankRogerEastonforgivingmeauniqueopportunitytoconductresearch
ontheArchimedesPalimpsest. I amespeciallygratefulforhisvaluable suggestions
and technical expertise. His multispectral imaging experiences and insight have
had a significant impact onmy research interests.
Rolando Raqueno has also been very helpful in explaining the algorithms used in
the software.
Ialso expressappreciationtotheWaltersArtMuseum,theowneroftheArchimedes
Palimpsest, and especially Keith Knox for creating the datacubes.
IwishtothankFranziskaFreyforherexcellentguidanceandadvice,includingallthe
hours spentreviewingmyresearch andplanningmytimeline. She is knowledgable
inthis fieldandhas showngreat support formywork. Her experience with various
museums, including the Hermitage in St. Petersburg, has been influential in my
careerpursuits.
I thank Twyla Cummings forher support and approval for my research, especially
with regards to this project. Her endorsementhas been very appreciated.
I also thankNatalie Russo forher extensive photographic experience and interests
inmuseumimagingandfine-artreproduction. Herfamiliaritywithimagingdevices,
workflows, and otherprojects has been a valuable resource.
I am especially grateful forMr. Iwao Numakura, who providedthe funding forthis
research. His generous support forthe School ofPrint Media has allowed students
to more fullyrealize theireducation through meaningful research projects.
Finally, I give a heartfelt thanks to my wife, Vanessa, for her enthusiasm, interest,
and encouragement, especially on certain research days that didn't seem to end.
Her support and strength ofcharacter keeps me wanting to do my best.
Ithas been aprivilege to workwith suchremarkable andbrilliant individuals.
in
Table ofContents
List ofFigures vi
Abstract viii
Chapter 1 - Introduction
1.1 The need to preserve ancient writings 1
1.2 TheArchimedes Palimpsest 2
1.3 Identifying theArchimedes text 3
1.4 Aneed formultispectral imaging 3
Chapter 2 - TheoreticalBackground
2.1 Introduction 6
2.2 Charge-coupleddevice (CCD) 6
2.3 Multispectral datacube 9
2.4 X-ray fluorescence 9
2.5 ENVI software 12
2.6 Principal component analysis (PCA) 12
2.7 Minimumnoise fraction (MNF) 13
2.8 Spectral classification 14
2.9 Spectral classification supervised 15
2.10 EDAX datacube limitation 16
Chapter3 - AReview ofLiterature in the Field
3.1 Introduction 17
3.2 Developing MSI forancient manuscripts 17
3.3 Other ancientmanuscriptprojects involving MSI 19
3.4 Different methods ofMSI used in ancient studies 21
3.5 Characterrecognition and facsimile reproduction 23
3.6 Atale oftwo inks 23
3.7 Parchment preparation 25
3.8 Imaging the palimpsest 26
3.9 X-ray fluorescence and theArchimedes Palimpsest 30
3.10 Conclusion 32
iv
Chapter 4 Hypothesis
-
4.1 Hypothesis 33
4.2 Otherquestions forresearch 33
4.3 Research limitations 34
Chapter 5 - Methodology
5.1 Objectives 35
5.2 XRF data evaluation 35
5.3 RGB composite image 36
5.4 Literature review preparation 36
Chapter 6 Results
-
6.1 Scanonedatacube 37
6.2 Classification 39
6.3 Scanonedatacube analysis PCA 41
6.4 Scanonedatacube analysis MNF 43
6.5 Creating subsets 43
6.6 Subset analysis PCA 44
6.7 Subset analysis MNF 46
6.8 Pseudocoloring 48
Chapter 7 - Summary and Conclusions
7.1 Summary 51
7.2 Conclusions 51
7.3 Recommendations for further investigation 52
List ofreferences 53
AppendixA: Glossary ofterms 61
Appendix B: Datacube histogram & subsets 67
Appendix C: Composite RGB images 69
List ofFigures
Figure 1: TheArchimedes Palimpsest 2
Figure 2: Manuscriptpages: 1906 vs. present condition 4
Figure 3: Electromagnetic spectrum 8
Figure 4: Formation ofa datacube 8
Figure 5: Stages ofX-ray fluorescence 10
Figure 6: X-ray fluorescence spectrum 11
Figure 7: Preparing parchment forwriting 25
Figure 8: Scribe writing onparchment 25
Figure 9: Tungsten vs. ultraviolet illumination 28
Figure 10: Spectral signatures ofthe ink layers 28
Figure 11: Monochromatic images used to create aRGB composite image 29
Figure 12: Pseudocolored palimpsest image 29
Figure 13: Iron andpotassiumX-ray fluorescence images 31
Figure 14: Using X rays to illuminate an illumination 31
Figure 15: Scanonedatacube spectrum 38
Figure 16: Parchment and inkwithinthe datacube 38
Figure 17: Four layers oftextvisible 39
Figure 18: Unsupervised classificationresults 39
Figure 19: Regions ofinterest 40
Figure 20: Supervised classificationresults 41
Figure 21: Principal component analysis results 42
Figure 22: PCAeigenvalues 42
Figure 23: Location ofsubsets 43
Figure 24: PCAresults for Subset 13 44
vi
Figure 25: PCAresults for subsets 45
Figure 26: MNF results for Subset 13 46
Figure 27: Unique MNF images 47
Figure 28: Creating composite RGB images inAdobe Photoshop 48
Figure 29: PseudocoloredXRF images 49
Figure 30: 3D palimpsestimages 50
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ABSTRACT
The Archimedes Palimpsest is a manuscript that has been preserved for
approximately 1,000years.Amongitspages aresomeofthefewknownsourcesoftreatises
from the Greek mathematicianArchimedes. The writing has been overwritten with prayer
text, called the Euchologion, and portions of the faded Archimedes text are difficult to
read. This research investigates methods to detect the presence ofink in the Archimedes
Palimpsest using state-of-the-art image processing techniques applied to data from X-ray
fluorescence (XRF) scans.
In an effort to extract more legible text, various methods of imaging have been
appliedtotheArchimedesmanuscript. RecentX-rayfluorescence images ofthepalimpsest
suggest the possibility of detecting individual text layers and isolating them from each
other. This is encouraging, since many ofthe pages have also been partially masked by
gold-leafed, Byzantine-style artwork, making theArchimedes writing difficult to see with
the human eye.
The scans measure the X radiation emitted by atoms on the pages that have been
excited by other higher energy X rays incident to the parchment. This caused certain
elements within the manuscript, such as the iron in the ink, tofluoresce at energies that are
specific to the particular material. Atotal of2,000 different energy levels, or bands, were
recorded. To evaluate the data contained in this large number ofbands, a single data set
was createdthat included allbands, referredto as a"datacube," which shows thetransition
ofeach pixel through the spectrum. Special image processing tools, developed for use in
the field ofremote sensing to process aerial and satellite data, canbe usedto detect certain
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