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National and international standards exist to ensure that data will
be interchangeable between systems and institutions and sustainable
in the long term, and that systems and applications will themselves
be interoperable. They are the tools that make accessible, sustainable,
and interoperable digital image collections feasible. Adherence to
data standards (for instance, by stating than an image is a reproduction
of The Last Supper by Leonardo da Vinci in a predictable and
recognized way) allows precise search and retrieval and may also
save cataloguing and indexing time by making it possible to
incorporate portions of documentation records from other institutions
or previous projects into new records. The transitory nature of digital
technology demands that technical standards be applied to the creation
and documentation of digital image files if they are not swiftly
to become defunct.
There are many data, descriptive, indexing, and technical standards
available, developed by various institutions and communities. The
difficulty usually lies in the selection of the most appropriate
combination of standards and their customization, if necessary, to
suit the particular needs of the institution and project. If possible,
choose open standards rather than proprietary ones,
as the latter may be idiosyncratic and/or reliant upon knowledge
or equipment that may not always be freely and generally available,
and thus lead to a sacrifice of interoperability and longevity. The
National Digital Library Program of the Library of Congress, the
California Digital Library, and the Colorado Digitization Program
are some examples of groups that have made available their own standards,
guidelines, and best practice recommendations for all aspects of
imaging projects, and these can be immensely helpful (see Online
Resources). When considering adopting a standard, it is important
to consider how well established vendors support it and the depth
of its user base. For instance, individual manufacturers and developers
may support different subsets of the total specifications for a technical
standard or modify specifications to the extent that the standard
is broken. This can lead to decreased interoperability. Researchor
consultation with an experienced imaging specialistcan help sort
out how well a standard is supported and by whom.
Technical standards addressing a broad range of information technology
issues, including file formats and technical metadata schemas,
are maintained and developed by international organizations. Examples
include the International Organization for Standardization (ISO);
the International Electrotechnical Commission (IEC); the Institute
of Electrical and Electronics Engineers (IEEE); the International
Telecommunications Union (ITU); and the World Wide Web Consortium
(W3C), which develops vendor-neutral open standards and specifications
for Internet and Web-based transactions, with the intent
of promoting interoperability. National standards bodiesincluding
the American National Standards Institute (ANSI), the U.S.
National Information Standards Organization (NISO), the British
Standards Institution (BSI), and the German Deutsches Institut
für Normung (DIN)not only define and endorse their
own standards but also support the work of international agencies.
The NISO Data Dictionary: Technical Metadata for Digital Still
Images (released as a draft standard in 2002) is particularly
worthy of note, because it was developed for cultural institutions
(and other organizations) interested in maintaining collections of
digital still images. (See Selecting a Metadata Schema). Technical
standards may also be developed within an industry or an individual
company. These may or may not be subjected to a formal standards-making
process and are often proprietary.
Note that standards evolve and new standards emerge. Ensuring that
imaging processes conform to current standards will involve vigilance
and a continual investment in updating and migrating information.
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