Digital
Imaging Program at the
Nantucket Historical Association Research Library
Our
purpose
Our goal is to have all our historic photograph
collection scanned and available individually catalogued
in our database. However, this does not necessarily
include the photographs from the NHA archives, all
images within individual photograph collections
and scrapbooks, manuscript items, books, or other
library material. The goal of the image database
is to facilitate access by patrons and staff and
to streamline requests for reproduction of images
and produce more income from the images.
Selection
of images to be scanned
The NHA Research Library photographic collections
serves several communities, each with different,
but often overlapping goals and needs. The community
that places the highest number of orders for photographs
are publishers of magazines and books; next in quantity
of users is the community of scholars; and finally
the community of individual information seekers,
typically seeking images of their families and historical
photographs of their houses. The photographic collection
is also heavily used by NHA staff for publications.
However, in terms of staff time required to serve
these communities, the communities of individual
seekers and NHA staff require more time for explanation
and assistance from the NHA Research Library staff.
While we do have the goal of scanning all of our
collection, we will first select images to help
us serve these four communities more efficiently.
Online access to our image database will aid in
this goal significantly.
Long
term intentions of the digital file
Each archival master image will be written to two
CDs. One copy of this CD will be retained at the
NHA Research Library; a second copy will be deposited
at the NHA main office at the Peter Foulger Museum
on Broad Street. This will accomplish two goals.
First, the digital image will be separate from the
original items and the other CD as insurance against
disastrous damage to each building. Second, NHA
staff members (heavy users of the collection) will
have access to an uncompressed high quality image
for their own uses without needing research assistance
from the NHA Research Library staff.
Format of images
We will be storing images in four formats. The master will be stored on CD and the reference and thumbnails will be available on the web and accessed by the online database.
Archival
Master: created from initial scan of the
original material. These digital masters will be
burned on CD-ROMs and put on a refreshment cycle
of ten years. The archival files will be used to
create the reference and thumbnail files
Format: TIFF
Spatial Resolution: maximum 5000 pixels across the
long dimension
Uncompressed
Unedited
Serves as a long term source for derivative files
Can serve as surrogate for the original
High quality
Large file size
Used for creating high quality print reproduction
In-house
Reference: an image to live on our server
Format: JPG
Spatial Resolution: maximum 5000 pixels across the
long dimension
Compression: 9:1
Minor manipulation (auto levels)
Useful for most print reproduction needs
Allows close in-house examination of print
Web
display image: For quick loading display
on the web
Format: JPG
DPI: 72
Size: 600 pixels across
Compression: 5:1
Used in place of master image for general web access
Generally fits within viewing area of average monitor
(600 dpi)
Reasonable file size for fast download time; does
not require a fast network connection
Acceptable quality for general research
Compressed for speed of access
Web
display thumbnail:
Format: JPG
DPI: 72
Size: 200 pixels across
Small size and compressed for fast download time
of multiple images on a page
Not meant for close viewing.
