Advanced Imaging Services at
KU Leuven Libraries
Bruno Vandermeulen
Hendrik Hameeuw
@imagingkuleuven

Content & Scoop
• Digitisation and Imaging at KU Leuven Libraries
• Standard Multi-Spectral Imaging
• Multi-Light Reflectance Imaging
o White Light Portable Light Dome
o Multispectral Portable Light Dome
 what is the technology
 roadmap to successful results
 examples of projects & results
 incorporation library services
2

Digitisation and Imaging at KU Leuven
Libraries
3
KU Leuven Libraries
Library ServicesLIBISSpecial CollectionsArtes2Bergen
Policy Unit
Administration, Finance,
HR, Communication
SBIB
GBIB
FBIB
PBIB
RBIB
EBIB
Faculty
libraries
Digitisation &
Document Delivery
Document Delivery
(ILL & scan on
demand)
Research & Policy
Development
Document
Processing
Policy Support &
Advise
Digitisation
Imaging Lab

Digitisation and Imaging at KU Leuven
Libraries
• Digitisation and Document Delivery Department
• Focus on projectmanagement (in house and outsourced digitisation
projects)
• Imaging Lab
• Focus on quality
• Respect for the materiality of objects (adapted infrastructure)
• Consistent (high) quality level based on international standards
• Close collaboration with research (such as Book Heritage Lab)
• Implementing techniques to advance research
• Development and implementation of new tools
• Not limited to KU Leuven collections
4

Standard Multispectral Imaging
Technology
5

Technology
6
• Beyond the visible light/spectrum
 Based on photography
 Outside the “comfort” zone of standard
practice
 Extra (expensive) equipment
• New possibilities for visualisation of
features not visible to the human eye
 More complex capture procedures
 Slower imaging
 More complex storage issues
 Extra research & dissemination strategies
Effect of MS imaging on canvas paintings
The electromagnetic spectrum

Technology: Camera
7
Standard filtering, blocking of visible light
towards a RGB pattern
(Source: http://eladorbach.blogspot.com)
Removal of UVIR and AA filters
(Source: https://blog.mingthein.com)
• Normal camera:
• 400-700 nm
• Modified (UV and IR sensitive)
• 310-1100 nm
• 310-400: UV
• 400-700: VIS (white light)
• 700-1100: IR
• (Without Bayer-filter)
Converted DSLR camera we selected

Technology: Lens
8
• Technical limits of standard lenses
 Hotspots (internal reflections)
 Shift in plane of focus
Chromatic aberration in standard lenses causes different
wavelengths of light to have differing focal lengths (Source:
Lens6a.png, Creative Commons Attribution-Share Alike 3.0
Unported license.)

Technology: Lens
9
• CoastalOpt 60 mm UV-VIS-NIR
• Full Apochromatic range 315 nm - 1100 nm
• Fluorite glass elements

Technology: Light sources
10
• 2 options:
 Emitted light is broad spectrum
 Emitted light in narrow spectrum
 (narrow) band pass filters need to be used to filter the emitted and reflected light
 Very accurate, but expensive and less flexible
white light + IR
light source
IR band pass
reflection
1 2
narrow band
emitter: blue
reflection

Technology: Light sources
11
• 2 options:
 Emitted light is broad spectrum
 Emitted light in narrow spectrum
 (narrow) band pass filters need to be used to filter the emitted and reflected light
 Very accurate, but expensive and less flexible
white light + IR
light source
IR band pass
reflection
1 2
narrow band
emitter: blue
reflection
UV emitter
or

Technology: Calibration
12
• Conventional Technical Photography (TP)
 Established imaging standards (Metamorfoze, FADGI,
…)
 Based on widely adopted commercial calibration
cards and color targets (X-Rite Colorchecker SG, …)
• Multispectral Imaging (MSI)
 UV target
 Diffuse Reflectance Standards
(i.e. Spectralon)
 Pigment chart

Technology: processing
• Image stack
• False color images
• Enhancement
processing
• Advanced processing
routines (PCA, spectral
unbinding, …)
• to visualize features
hardly or not visible to
human eye
13
KU Leuven, Tabularium MS 1073

Standard Multispectral Imaging
Roadmap KU Leuven
14

First trials with inadequate equipment
15
• Nikon D100 (limited sensitivity in IR region), 2008
• Standard VIS lens
• Tungsten light
• Cheap online acquired IR filter

First trials with inadequate equipment
16
• Phase One Achromatic Back (2011)
• Standard 80 mm VIS lens
• Cheap online acquired IR filter
• UV: blacklight
Color IR UV
KU Leuven, Tabularium MS 1007, 042V
Color IR UV
KU Leuven, Tabularium MS 1014, 038V

Equipment: Filters
17
• Filters 1
 Cheap online
acquired filters
• Filter kit 2
 Forensic Photo
kit: Peca
• Additional filters
 10 nm
Bandpass filters

A first assignment
18
• Antifonarium illuminations
• Simple procedure
• Immediate results
o Underdrawings
o Surface characteristics VIS IR 850 nm UV 365 nm
Private collection, Antifonarium, f 015R, detail 01
VIS IR 850 nm UV 365 nm
Private collection, Antifonarium, f 015R, detail 02

Equipment: Light sources
19
• White light + IR emitter: standard studio
flashes or tungsten light (halogen)
• UV emitter: UV tube 365 nm and
Black Light

First funded projects
20
• Development of Multispectral Portable Light Dome (RICH-project
2012)
 see infra
• Establishing simple, standardized recording & processing pipeline for
multispectral imaging of fragile Ancient Egyptian figurines (EES-
project 2014)
 Full spectrum converted NIKON D610 DSLR camera
 Apochromatic lens
 Forensic Photo Kit: Peca filters
 TechSpec Hard Coated 10 nm bandpass filters (356, 730, 780, 850, 930 nm)
 Calibration in VIS, manual/visual adjustments in UV and IR

EES-project
21
• Recordings

EES-project
22
• Limited number recordings
• Simple post-processing
o Photoshop color-channels
o Enhancement processing
False Color-IR B-channel LAB
based on False Color-
IR
VIS
RMAH-MRAH: E.7460

New filters & New calibration
23
• MidOpt filters
oNarrow bandpass filters
o Across/Overlap entire spectrum: c. 320nm – 950nm
o For stability  equipped with magnetic filter rings
lens
magnetic holder
magnetic filter ring
filter
attached
attached
Selection of bandpass filters represented across
electromagnetic spectrum
(Source: Curve Compare sheets MidOpt)

Technology: Filters
24
• Filter kit 3
 Selection of MidOpt filters
324nm Near-UV 405nm Violet 440 nm Violet 505nm Cyan 590nm Orange
635nm Light Red 400-700nm VIS 660nm Dark Red 695nm Red/IR 725nm NIR
780nm NIR 830nm NIR 880nm NIR 940nm NIR

New filters & New calibration
25
• Calibration
MSI calibration card
by Cultural Heritage Science Open Source
Object-Level Target with
Munsel patches
by Image Science Associates
Multi-step target with
spectralon
by Labsphere

26
New filters & New calibration
• Calibration via
reflectance values
monitoring (color readout)
in Capture One (L.A.B.)
oIR goes down on Munsel
patches
o UV much to low on MSI
calibration card and
Munsel patches
oOnly spectralon stays
consistent

New filters & New calibration
27
• Calibration with
spectralon
o Rough tuning during
capture
 Aperture
 Shutter speed
 ISO
o Fine tuning in post-
processing
Exposure
Source: Labsphere Spectralon Standards Datasheet

Limits of standard Multi-Spectral Imaging
28
• Time consuming  easily min per sequence
• Stability  throughout the recording sequence
• Post-processing  fine-tuning reflectance
• Dark room  for all-including capture
• Price  all basic equipment together: ±12870 €
- Camera (D610) + Conversion: 1900,-
- Lens (CoastalOpt UV-VIS-IR): 5500,-
- MS Filter set + magnetic rings: 4500,-
- Software (Capture One): 300,-
- Calibration (spectralon): 670,-

Benefits of standard Multi-Spectral Imaging
29
• Allow standard MSI output  conservation, underdrawings,
materiality, …
• Relative simple procedure  doable for a normal institute photo-lab
• Standard service  incorporable in service catalog
• Extra services  towards research and conservation
• Price  Investment can be spread over time

An example of extra service
30
• Identification of materials
1. Capture of reference material
Spectralon reference
Historical Pigment Checker (v.5)
by Cultural Heritage Science Open Source

An example of extra service
31
• Identification of materials
1. Capture of reference material
2. Capture of heritage object
same
settings
Spectralon reference
KU Leuven - Ms.1333

An example of extra service
32
• Identification of materials
1. Capture of reference material
2. Capture of heritage object
3. Make spectral curves
oImageJ (Open Source)
o Spectral fingerprint of pigment
o Conversion in spreadsheet of
reflectance values
 method as proposed on Archiving 2018, Washington by
Fenella France & Meghan Wilson, Library of Congress
Screenshot of establishing MS reflectance curves in ImageJ workspace

An example of extra service
33
• Identification of materials
1. Capture of reference material
2. Capture of heritage object
3. Make spectral curves
4. Compare
For this example a positive
identification of ‘azurite’
The MS reflectance curve as plotted in Excel
for the blue pigment on Ms. 1333 of KU
Leuven Libraries
The MS reflectance curve as plotted in Excel
for the azurite pigment patch Pigment Checker
(v.5) by Cultural Heritage Science Open Source

(near) Future
• 3Pi: Papyrus Parchment Paper Imaging
• (Book Heritage Lab (FTRS), Illuminare, ESAT,
KU Leuven Libraries)
• Integration of both visualization and analytical
tools (tools for data creation)
• Processing
• Dissemination
34

Multi-light Reflectance Imaging
White Light Portable Light Dome
Multispectral Portable Light Dome
Technology & Roadmap
35

The system
36
OUTPUT
 Relightable Images/Pixels
 Enhanced visualization shaders
 Genuine 3D
 BRDF analyses
1980
Theoretic principles
of photometric
stereo
1999
Malzbender’s
dome @ HP
2003
Start of PLD
project @
KU Leuven
2005
PLD for cuneiform
studies
2011
PLD for documentary
heritage
2014
Multispectral
PLD
• Multi-light Reflectance Imaging (MLRI)
• Based on principles of Photometric
Stereo (PS)
• Related with RTI

Acquisition devices
37
• The Portable Light Domes
- WL Microdome
- WL Minidome (version 1 & 2)
- MS Microdome
- MS Minidome
Microdome Minidome (Version 1) Minidome (Version 2)
MS Microdome
Minidome (Version 1)

Acquisition devices
38
• LEDs
• Ultraviolet (UV): 365 nm
• Blue: 460 nm
• Green: 523 nm
• Red: 623 nm
• Infrared (IR): 850 nm
FINGERPRINT project (Imaging Bruegel Graphic Work) ARTGARDEN project (Imaging Closed Gardens)
EES project (Imaging Ancient Egyptian Figurines)

Standard output
39
Multispectral Imaging of an Egyptian Mummy Portrait
Viewer interface with cuneiform tablet
↙
Compilation of
multispectral images (IR, R,
G, B, UV, false color PCA’s)
→ Standard visualisations in
the desktop viewer, white
light dataset
↘

Principles in brief
40
Viewer interface with cuneiform tablet
Final Compressed Data File
(.cun or .zun)
Greek silver coin – Leuven Art collection
(o.i. 522)
Greek silver coin – Leuven Art collection
(o.i. 522)
3D models
per side
Photometric
Stereo
x228
or
x260

From white light to multispectral
41
Viewer interface with cuneiform tablet

From white light to multispectral: Case 1
42
Visualization and measuring of the topography: Leuven, Mauris Sabbe Library – leather book binding
• White Light PLD
 Visualisation
Color shader with perpendicular light

From white light to multispectral: Case 1
43
Visualization and measuring of the topography: Leuven, Mauris Sabbe Library – leather book binding
Color shader with raking light
• White Light PLD
 Visualisation

From white light to multispectral: Case 1
44
Visualization and measuring of the topography: Leuven, Mauris Sabbe Library – leather book binding
Color shader with raking light & measure tool
• White Light PLD
 Visualisation

From white light to multispectral: Case 1
45
Visualization and measuring of the topography: Leuven, Mauris Sabbe Library – leather book binding
Shaded shader with raking light
• White Light PLD
 Visualisation

From white light to multispectral: Case 1
46
Visualization and measuring of the topography: Leuven, Mauris Sabbe Library – leather book binding
Shaded shader with raking light
• White Light PLD
 Visualisation

From white light to multispectral: Case 1
47
Visualization and measuring of the topography: Leuven, Mauris Sabbe Library – leather book binding
Sketch1 shader
• White Light PLD
 Visualisation

From white light to multispectral: Case 2
48
Conservation – monitoring surface conditions before and after (Private
Collection – Illuminated Manuscript, Antiphonary, folio 4r)
untreated treated Color shader with
normal relighting
• White Light PLD
 Physical analysis

From white light to multispectral: Case 2
49
untreated treated
Color shader with
raking light
• White Light PLD
 Physical analysis
Conservation – monitoring surface conditions before and after (Private
Collection – Illuminated Manuscript, Antiphonary, folio 4r)

From white light to multispectral: Case 2
50
untreated treated
Shaded shader with
raking light
• White Light PLD
 Physical analysis
Conservation – monitoring surface conditions before and after (Private
Collection – Illuminated Manuscript, Antiphonary, folio 4r)

From white light to multispectral: Case 2
51
untreated treated
Color shader with
measure tool
• White Light PLD
 Physical analysis
Conservation – monitoring surface conditions before and after (Private
Collection – Illuminated Manuscript, Antiphonary, folio 4r)

From white light to multispectral: Case 2
52
untreated
treated
-5
-4
-3
-2
-1
0
1
0 10 20 30 40 50 60 70 80 90
Folio 34R
Folio 34R Treated
• White Light PLD
 Physical analysis
Conservation – monitoring surface conditions before and after (Private
Collection – Illuminated Manuscript, Antiphonary, folio 4r)

From white light to multispectral: Case 3
53
MS PLD reflection maps of the Pigments
Checker (CHSOS); Above: ultramarine;
Below: azurite
Reflection maps and histogram.
Above: pixel and zone X ultramarine;
Below: pixel and zone Y, azurite
Detail in Bible of Anjou (f001v): Pigment analyses - both azurite and
ultramarine appear as blue (C = false color: IR/G/B)
Analysing the reflections in 5 spectral bands
• Multispectral PLD
 Spectral analysis

From white light to multispectral: Case 4
54
• Multispectral PLD
 Combined analysis (physical & spectral)
Detail on NHD27 ‘Luxuria’ by Bruegel
(drawing SII132816 & print SII22656, both KBR, Brussels)

From white light to multispectral: Case 4
55
Detail on NHD49 ‘View of Tivoli’ by Bruegel
(print SI9412, KBR, Brussels)
Legend
A: Standard Phase One image
B: Backlight Phase One image
C: Multispectral PLD, normal RGB representation
D: UV representation with MS PLD
E: Shaded shader of MS PLD viewer
F: False color Red-Green-UV
• Multispectral PLD
 Combined analysis (physical & spectral)

Library Services and Advanced
Imaging
56

Service integration
57
Preparation
• Project application
• Agreement
• Book loans
• Transport
• Pre-/conservation
Metadating
Collection /
Items
• Analysis existing metadata
• Creating (extra) metadata
• Creating metadata for digitisation (‘digi numbers’)
Standard
digitisation
• Imaging
• Checks and processing
• Upload
Enrichment
• OCR
• High resolution viewer
• Advanced imaging
• …
Ingest and
publishing
• Metadata – image matching
• Ingest
• Checks
Post-care
• Archiving documentation
• Image preservation
Advanced
imaging
Data work
environment
Data delivery

Added value
58
• Integrated service: standard digitisation and imaging
• Embedding advanced imaging on institutional level
• At the service of researchers, in close collaboration
• Build up of high-end non-standard infrastructure through external funding
• Pooling of equipment, resources and expertise
• Library = lab to test out routines, develop workflows, …
• High(er) visibility

Thank you!
59
Contact:
Bruno Vandermeulen: bruno.vandermeulen@kuleuven.be
Hendrik Hameeuw: hendrik.hameeuw@kuleuven.be
@imagingkuleuven
https://bib.kuleuven.be/english/research
https://enrichingheritage.wordpress.com
Projects involved:
https://portablelightdome.wordpress.com
https://fingerprintbruegel.wordpress.com