Cultural Heritage Destruction: Documenting Parchment Degradation via Multispectral Imaging
Alejandro Giacometti, Lindsay MacDonald (UCL) and Alberto Campagnolo (University of the Arts)
Institute of Classical Studies Digital Seminar 2012
Friday June 22nd at 16:30, in Room G37, Senate House, Malet Street, London WC1E 7HU
Digital surrogates of documents have become an indispensable tool for scholars and archives. Digital surrogates provide an easily accessible, non-degrading resource for research and study. Additionally, a variety of imaging technologies have been utilised to examine the characteristics of the originals, such as X-ray imaging, imaging in the infrared spectrum, and multi-spectral imaging. These provide additional information about the physical characteristics and condition of the document. However, current digitisation efforts have been concentrated on documents in their current state. In this project we aim to investigate the process of document degradation using multispectral imaging.
We obtained an 18th Century manuscript de-accessioned from the London Metropolitan Archives. Although it is in good physical condition, this manuscript has been determined to hold no historical value, and therefore was provided to us for experimentation. It comprises two large sheets, written in iron gall ink on prepared animal skin – or parchment – and measures approximately 70×70 cm. It is dated 11th August 1753, in the reign of George II, and appears to be an indenture (contract) between a Mr John Sherman and Mr Christ Gardiner.
From the document will be cut 23 flat square sections of 8×8 cm, with each section containing written text. Each section will be exposed to an external destructive agent in order to force a rapid and controlled form of degradation. The agents will include mechanical damage, heat, humidity, abrasion and a variety of substances with different chemical properties. Each will affect the appearance and condition of the parchment samples.
Each sample will be imaged before and after the damage, using two different cameras, in combination with two lighting systems for both reflective and transmissive imaging, under a range of bandpass filters. The cameras include an RGB high-resolution digital SLR (Nikon D200), which captures images in the visible spectrum, and a scientific monochrome camera (Kodak), which captures images in both the visible and near-infrared spectrum. With each camera, a set of 20 nm bandpass filters centred at regular intervals will be used.
This project will provide a set of multi-spectral images showing both the initial and damaged state of a manuscript. These images will be fully documented and released publicly as a resource for the research community. They will provide insight into how a manuscript reacts visually and physically to various forms of degradation, a guide for conservators, a resource for quantitative evaluation of image processing algorithms for information recovery, and possibly other research activities in conservation, image processing, computer graphics, and medical imaging.
The seminar will be followed by wine and refreshments.