The Preservation of Digitized Reproductions
Approved by the Society of American Archivists Council
June 9, 1997
The digital world challenges our notion of preservation. Traditional
preservation, as responsible custody, works best when evidence of human
activity can be touched and sensed directly, when the value of the evidence
exceeds the cost of keeping it, and when the creators, keepers, and users
of the evidence work cooperatively toward the same ends. While this evidence
is traditionally seen as documents on paper, increasingly archivists must
preserve a variety of formats, including still and moving images and sound
recordings. All of these media can now be reproduced in digital form.
Such digital information cannot be used without the help of a machine.
World-wide access through the Internet raises many questions about who
owns digital information, who has the right to profit from other's work,
and who has responsibility for guaranteeing or regulating access to valuable
information. The pace of technological change is at once blinding and
stubbornly inadequate. Preservation of digital information is not so much
about protecting physical objects as about specifying the creation and
maintenance of intangible electronic files whose intellectual integrity
is their primary characteristic.
Preservation in the digital world is not exclusively a matter of longevity
of optical disks, magnetic tape, and newer, more fragile storage media.
The viability of digitized files is much more dependent on the life expectancy
of the access system—a chain is only as b as its weakest component.
Today's digital media should be handled with care, but most likely will
far outlast the capability of systems to retrieve and interpret the data
stored on them. We can never know for certain when a system has become
obsolete. Archives must prepare to migrate valuable digitized data, indexes,
and software from one generation of computer technology to a subsequent
generation. The use of digital technologies from a preservation perspective
requires a deep and long standing institutional commitment to long-term
access, the full integration of the technology into information management
procedures and processes, and significant leadership in developing appropriate
definitions and standards for digital preservation.
Selection for preservation in digital form is not a one-time choice made
near the end of an item's life, but rather an ongoing process intimately
connected to the active use of the digital files. An evaluation of the
archival value of a record series, a manuscript collection, or a group
of photographs in their original format is the necessary point of departure
for the preservation of the digital version. The archival perspective
first requires a commitment to preserving the integrity of a group of
records as well as their contextual metadata. The archival value of these
materials focuses on their value as evidence, not just as carriers of
information. An assessment of the need for networked or rapid access,
the protection of fragile originals, of the prevention of degradation
from multi-generational copying must also be considered in the decision
to convert documents from paper, film or analog media to digital form.
The mere potential for increased access to a digitized collection does
not add value to an underutilized collection. It is a rare collection
of digital files indeed that can justify the cost of a comprehensive migration
strategy without factoring in the larger intellectual context of related
digital files stored elsewhere and their combined uses for research and
Quality in the digital world is conditioned by the limitations of capture
and display technology. Digital conversion places less emphasis on obtaining
a faithful reproduction of the original than on finding the best representation
of the original in digital form. Mechanisms and techniques for judging
quality of digital reproductions are different and more sophisticated
than those for assessing microfilm or photocopy reproductions. The primary
goal of preservation quality is to capture as much intellectual and visual
or aural content as is technically possible and then display that content
to users in ways most appropriate to their needs.
In the digital world, a commitment to the integrity of a digital file
begins with limiting the loss of information that occurs when a file is
created originally and then compressed mathematically for storage or transmission
across a network. Structural indexes and data descriptions of materials
prepared as discrete finding aids or bibliographic records must be preserved—as
Metadata—along with the digital files themselves. The preservation
of intellectual integrity also involves authentication procedures, like
audit trails, to make sure files are not altered intentionally or accidentally.
In the digital world access is the central distinguishing quality of
preservation. Digital technology is more than another way to copy a deteriorating
document. Imaging involves transforming the very concept of format, not
simply creating an accurate picture of a document, photograph, or map
on a different medium. Preservation in the digital world is the act of
ensuring continuing access to a high-quality, high-value, well-protected,
and fully-integrated version of an original source document. Responsibility
for long-term access to digital archives rests initially with the creator
or owner of the materials. The resource and administrative implications
of this fact cannot be minimized and must play a role in the decision
to digitize archival and manuscript materials.
We know that the impulse to record and keep is part of our human nature.
Like the clerks and scribes who went before them, archivists increase
the chances that evidence about how we live, how we think, and what we
have done will be preserved. It has long been the responsibility of archivists
to assemble, organize, and protect this evidence. Long-term preservation
of information in digital form encompasses the initial choice of a technology,
the use of digital technologies for reproducing historically valuable
materials, and the protection of the resulting digital information itself
for as long as that information has value to an institution and clients
Preservation of Digitized Reproductions—Selected Readings
Besser, Howard and Jennifer Trant, Introduction to Imaging: Issues
in Constructing an Image Database. Santa Monica: Getty Art History
Information Program, 1995.
Conway, Paul. Preservation in the Digital World. Washington, D.C.:
Commission on Preservation and Access, March 1996.
Hedstrom, Margaret. Understanding Electronic Incunabula: A Framework
for Research on Electronic Records. American Archivist 54 (Fall
Kenney, Anne R. and Stephen Chapman. Digital Resolution Requirements
for Replacing Text-based Material: Methods for Benchmarking Image Quality.
Washington, D.C.: Commission on Preservation and Access, 1995.
Lynch, Clifford. The Integrity of Digital Information: Mechanics and
Definitional Issues. Journal of the American Society for Information
Science 45 (December 1994): 737-44.
Preservation of Digital Information: Report of the Task Force on
Archiving of Digital Information. Washington, D.C.: Research Libraries
Group and Commission on Preservation and Access, May 1996.