Paper Conservation: Decisions & Compromises

Imaging Characteristics of Graphic Materials with the Minidome (RICH)
Lieve Watteeuw | Bruno Vandermeulen | Jan Van der Stock | Pierre Delsaerdt |
Stefan Gradmann | Fred Truyen | Marc Proesmans | Wim Moreau | Luc Van Gool
KU Leuven, Faculty of Arts; Illuminare, University Library & ESAT-Visics,
Department of Electrical Engineering, Leuven, Belgium
The RICH project
RICH (Reflectance Imaging for Cultural Heritage,
KU Leuven, 2012-2015) is creating a digital imaging
tool for researching, studying, and exploring
material characteristics of library materials. In
2005, the first generation of the module was created
for reading cuneiform tablets in the department
of Assyriology of the University of Leuven
(KU Leuven). With the second generation of the
imaging devise, developed in 2013, the visualization
of paper and parchment artifacts, paper and
wax seals, illumination and bookbinding stamps
(gold- and blind tooled, on the back and on the
boards of bindings) is in development. The imaging
tool can create a sharp and exact image of
the surface in 2D+ and proofs to be an accurate
documentation tool for monitoring surface characteristics
of graphic materials.
Infrastructure
The digital imaging device, IMROD (Imaging
Module for Multi-spectral, Reflectance or 2D+), is
digitizing with omnimulti-directional lighting
and exports the result to 2D+ (Fig. 1). The technique
is based on polynomial texture mapping,
also known as Reflectance Transformation Imaging
(RTI), a technique of imaging and interactively
displaying objects under varying lighting
conditions to reveal surface phenomena. The
module is a hemi-spherical structure with a single
downward looking video camera (28 million
pixels). The object to be captured ( maximum 180
to 120 mm) lies in the center and is illuminated
from computer-controllable lighting directions,
through the subsequent activation of multiple
white LEDs. The different angles that illuminate
the surface of the artifacts are revealing extreme
details. Special attention is taken to produce raking
light to provide information on the surface
topography. For each illumination an image is
taken by the overhead camera, in total 264 images
for each object. After processing these 264
images, filters in the visualization system like
virtual lighting, shading and sketch are incorporated
in the software. The application of these
filters allows detailed documentation of surface
characteristics, irregularities, undulations, flaking,
lacunas and the different levels of loss of
the pictorial layers of the researched artifact.
After capturing the images, fine details can be
highlighted by the use of specific digital filters,
bringing out structures that would be less visible
Fig. 1: Dome for digitizing with omnimulti-directional
lighting and export the result to 2D+.
(© ESAT, KU Leuven)
Fig. 2: Last folio of a severely damaged 19 th century manuscript
on paper, imaged with raking light and adding a
shade filter. (© RICH, KU Leuven)
ICOM-CC Graphic Documents Working Group Interim Meeting | Vienna 17 – 19 April 2013
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