Permanent Pixels: Building Blocks for the Longevity of Digital Surrogates of Historical Photographs

221 Pages·2005·1.122 MB·English

by  René van Horik

Permanent pixels
Building blocks for the longevity of digital
surrogates of historical photographs
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This thesis has been made possible with financial support from:
– Delft University of Technology (DITSE BETADE)
– Netherlands Institute for Scientific Information Services (NIWI-KNAW)
– Data Archiving and Networked Services (DANS)
Printing: GrafiSchoth
Cover Design: Erwin van Krey
Copy-editing: Lorna Cullen
Copyright © 2005 René van Horik
All rights reserved. No part of this publication my be reproduced, stored in a retrieval
system, or transmitted, in any form or by any means, electronic, mechanical, photo-
copying, recording or otherwise, without the prior written permission of the author.
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Permanent pixels
Building blocks for the longevity of digital
surrogates of historical photographs
Proefschrift
ter verkrijging van de graad van doctor
aan de Technische Universiteit Delft,
op gezag van de Rector Magnificus prof. dr. ir. J.T. Fokkema,
voorzitter van het College voor Promoties,
in het openbaar te verdedigen op dinsdag  november 005 om 5:0 uur
door
Marinus Petrus Maria VAN HORIK
doctorandus in de geschiedenis
geboren te Aarle-Rixtel
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Dit proefschrift is goedgekeurd door de promotoren:
Prof. dr. H.G. Sol
Prof. dr. H. Koppelaar
Toegevoegd promotor: Dr. K. van der Meer
Samenstelling promotiecommissie:
Rector Magnificus Voorzitter
Prof. dr. H.G. Sol Technische Universiteit Delft, promotor
Prof. dr. H. Koppelaar Technische Universiteit Delft, promotor
Dr. K. van der Meer Technische Universiteit Delft, toegevoegd promotor
Prof. dr. F. C. J. Ketelaar Universiteit van Amsterdam
Prof. Dr. Ir. A. Verbraeck University of Maryland, United States of America
Dr. P.K. Doorn Data Archiving and Networked Services
Dr. S. Ross University of Glasgow, United Kingdom
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Preface
Science is not about finding the truth; it is about
finding hypotheses that can be demonstrated to be
consistent with reality. ([TAN98] p. 310)
The wish to write a dissertation has been latent ever since I started to work in the
field of the application of information technology in the Humanities. Since early
1989, I have been involved in several activities in which information technology
was applied to create, analyse and archive digital resources relevant for scholarly
research in the Humanities. My involvement in the Netherlands Historical Data
Archive (NHDA) – ironically often struggling for survival – made me realise how
valuable and vulnerable digital research datasets are. My activities in a wide range
of digital conversion projects in which a diversity of historical source material was
digitised strengthened my feeling that the digital surrogates, often created at a high
cost, run a great risk of being lost in the future. Increasingly, I have been intrigued
by the problems related to long-term access to digital data, but I realised that dig-
ital preservation is a very wide field of interest.
The BETADE research programme of Delft University of Technology had a
role to play in making my latent plans to start a PhD dissertation more concrete,
as document management and longevity of digital documents was one of its appli-
cation fields. My research proposal was focused on the longevity of a specific class
of digital document, namely digital surrogates of historical photographs. My expe-
riences concerning the digitisation of historical analogue sources, from 1997 on-
wards at Netherlands Institute for Scientific Information Services (NIWI-KNAW),
taught me that the digitisation of continuous tone sources, such as photographs,
is much more complicated and expensive than that of textual sources. By concen-
trating my research on the longevity of this specific type of document I expect to
contribute to the realisation of long-term access to this type of digital object rather
than to come to more general conclusions concerning digital preservation issues.
Of course, extrapolation of the research results to more general digital preserva-
tion principles can also be expected.
Within the context of the problem of long-term access to digital objects in gen-
eral this dissertation takes the longevity of digital surrogates of historical photo-
graphs into consideration. The focus on this specific type of digital data object has
two foundations. First, there is the ubiquitous view among archives, libraries and
museums that analogue originals and their digital counterparts are closely related.
The features of a digital surrogate, such as a scanned historical photograph, are
based on an assessment of the analogue original as well as the intended function
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of the digital surrogate, also in the long term. This gives the digital objects to be
preserved a very specific character that justifies the scope of this research on the
longevity of a specific digital data object.
The second reason for concentrating in this dissertation on a specific type of
digital data object is more pragmatic. The focus on the longevity of digital sur-
rogates of historical photographs enables the investigation of available building
blocks for digital preservation such as guidelines, procedures, tools, standards,
strategies and methods to enable long-term access to digital data objects. This dis-
sertation examines in detail the role of digital preservation strategies, file format
standards, content format standards, metadata schemas and other building blocks
for the realisation of durable digital surrogates of historical photographs.
It is obvious that the longevity of digital objects is very much determined by
the level of commitment of an organisation that considers itself as the curator
of the digital objects. This is much less a technical than an organisational issue.
Despite the fact that the organisational structure of the NHDA and its succes-
sor NIWI-KNAW turned out to be not very durable, the continual organisational
commitment to provide access to digital objects relevant for research in the Hu-
manities has prevented the loss of data archives up to now. Based on new insights,
the recently founded organisation DANS (Data Archiving and Networked Serv-
ices) took over and augmented the digital data archiving responsibilities of NHDA
and NIWI-KNAW. It is important that this organisation, just like its predecessors,
puts efforts into research into digital preservation in order to provide long-term
access to its digital assets.
I have appreciated the stimulating supervisory instructions of Professor Henk
Koppelaar and the comments of Professor Henk Sol. Kees van der Meer was my
companion at Delft and helped me to acclimatise. His day-to-day advice, sugges-
tions and discussions helped me on my way. I am very grateful to Peter Doorn of
NIWI-KNAW and DANS, who from the outset motivated me to embark on the
PhD research and who was very cooperative and flexible in establishing an agree-
ment between the BETADE research programme of Delft University of Technol-
ogy and NIWI-KNAW. I also very much appreciate the stimulating active involve-
ment of Peter in my research. Furthermore I owe a great deal of gratitude to the
other members of my promotion commission for their investment in my disserta-
tion.
I would like to thank Charles Dollar, one of the founding fathers of digital pres-
ervation solutions of electronic records, who participated in a BETADE workshop
and provided me with important initial research suggestions. I would also like to
thank Alexander Verbraeck and Ajantha Dahanayake, supervisors of the BETA-
DE research programme, and Frans Dondorp, my ‘roommate’ in Delft, for our
thought-provoking discussions. For the indispensable practical experience con-
cerning the digitisation and long-term archiving of digital photographic collec-
tions, I appreciate very much the collaboration in several projects of Edwin Klijn,
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Rutger Kramer, Yola de Lusenet, Laurents Sesink, Paula Witkamp, Douwe Zelden-
rust and Joris van Zundert, all working at different research institutes of the Royal
Netherlands Academy of Arts and Sciences.
And, finally, I owe much gratitude to Hilde and our daughters Hannah and
Vera for their patience and support during the period of writing ‘my book’.
Leiden, May 2005
René van Horik
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Contents
1. Introduction 11
1.1 Digitisation in memory institutes 12
1.2 Longevity of digital objects 14
1.3 Research 19
2. Digitisation and digital longevity in memory institutes 33
2.1 Digitisation of historical photographs 34
2.2 Digital longevity in memory institutes 49
3. Durable digital surrogates of historical photographs 81
3.1 Benchmarked digital capture process 82
3.2 Unambiguous formulation of preservation metadata 95
3.3 Durable access to digital objects 111
4. Experiments on the longevity of digital surrogates of historical photographs 123
4.1 Experiment 1: Durable digital image file format 124
4.2 Experiment 2: Durable digital image bitstream 132
4.3 Experiment 3. Durable formulation of preservation metadata 144
5. Evaluation of the experiments 163
5.1 The main outcomes so far 163
5.2 Emerging image file formats 166
5.3 Bitstream preservation with the help of the XML data format 168
5.4 Metadata of digital surrogates of historical photographs 171
6. Conclusion 177
6.1 Research findings 178
6.2 Extrapolation 182
6.3 Further research 184
Samenvatting 187
References 195
About the author 217
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