Maps are scanned by institutions from across the PALMM consortium,
by large- and small-scale digitization programs alike, and a variety
of imaging technologies is employed. Imaging technologies, for the most
part, are fully digital, relying upon digital camera backs. Some oversized
maps are digitized from analog 105 mm color-film format intermediaries,
while others - as a consequence of the artifacts history has bequeathed
to us - have been digitized from 35 mm color-slide film. Some small
maps are digitized with the aid of flatbed scanners. The technical details
of the scanning process are maintained by the holding institution if
not recorded in the description of the digitized map.
SELECTION
Maps are selected by the various curators of map, Florida history,
and area studies collections, as well as, geographic information systems
librarians of contributing institutions. The majority of maps are selected
for their relevance to the Florida
Heritage Collection, to another PALMM
Collection, or to an academic program. Additional information
about the collections from which maps are selected is available.
RESOURCE DESCRIPTION : Cataloging
Participating libraries are responsible for describing the maps selected
from their own collections. Description takes the form of either full
MARC catalog records or metadata subsequently processed into minimal
MARC catalog records. This description is seachable both within the
PALMM World Map Collections or within the catalogs of the PALMM institutions.
Additionally, as catalog records for these electronic resources is
contributed to OCLC and RLIN, the national bibliographic databases,
the collection's maps become searchable and accessible nationally
and internationally. Cataloging is expected to adhere to guidelines
developed by the Technical Services Planning Committee Cataloging
and Access Guidelines for Electronic Resources (CAGER).
As possible, given the size of source maps and the limitations of
imaging equipment, image capture adheres to the standards promulgated
by the Cornell Department of Preservation and Conservation (see Digital
Imaging for Library and Archives, Kenny and Chapman, 1996). A Quality
Index of 5 or better for visual images is required as possible.
Three types of images are created for all maps in the collection:
TIFF master, JPEG thumbnail and SID zoomable image. Participating
libraries create TIFF and JPEG images and submit them to FCLA, which
subsequently creates the SID derivative. As an exception, the digital
library facilities of both the University of Florida and the University
of South Florida process their own SID files.
TIFF images are created as the direct result of scanning source materials
(that is, as the native file format). TIFFs are archived as uncompressed
electronic masters. Bit-depth is appropriate to the source and its
anticipated use, and may be bitonal, 8-bit gray, 24-bit color, or
greater. Color images are created and maintained in the sRGB color-space.
Both hardware and images are calibrated and scanned to within the
tolerances promulgated by the Library of Congress for the American
Memory project. Images created from an analog film intermediary reflect
the quality of the source microfilm. Nearly all TIFFs are imaged in-house.
Solutions utilizing an analog film intermediary are usually vended
to commercial services.
Guidelines for post-image processing of TIFFs varies from PALMM institution
to PALMM institution. There is no shared aesthetic. And, even at a
single institution, a particular aesthetic may not be applied uniformly.
Most commonly, the scanning institution will created and archives
a TIFF image with minimal post-image processing. The most aggressive
of these minimal processes includes color balancing. More rarely and
selectively, advanced processes are applied as digital "restoration".
This process includes a number of image manipulation procedures based
on knowledge of period paper and ink manufacturing. Generally, it
is attempted only when a pristine off-print is required or the need
for one is anticipated.
TIFF images are used to create JPEG thumbnails using Adobe Photoshop
or Cerious ThumbsPlus in a batch executable process. The TIFF image
is resized setting the width to 630 pixels and the height relative
to width. Creation of SID files is a function performed by the LizardTech
SID encoder software.
Capture hardware differs from one institution to another,
but each institution generally employs a one image strategy. Scanning
institutions avoid, wherever possible, stitching images together
to reproduce a single map; image stitching is a particularly imperfect
process when working with maps.
The Flatbed scanners used are various. The majority are highend
color-calibratable scanners, with minimum 600 dpi native hardware
optics. Among the best of these systems is the University of South
Florida's Contex FSC 6040 Chroma wide format color scanner that
can scan up to 800 dpi optical, 24-bit color, using the WIDEImage
2.2 scanning application. The unit can accept maps up to 40"
in width. Image processing and final quality control applications
vary as well. The majority of flatbed scanning workstations employ
Adobe Photoshop, but JASC PaintShop Pro and ImageRobot are used
also.
Two scanning institutions, the University of Florida and the University
of South Florida operate planetary digital cameras for capture of
oversized maps.
The University of Florida's equipment is a Phase One PowerPhase FX digital
camera back with a 10,500 pixel by 12,600 pixel 24-bit color capture
capacity. The camera back is mounted on a planetary ZBE Satellite universal scanning system (no longer manufactured),
including three lens mount & bellows, camera stand, and automated
control system for calibrated imaging. This scanning system has
the look and feel of a commercial microfilming camera. A Rodenstock
Rodagon 135 mm professional enlarging lens (f/5.6) with
an AR-1 high aspect ratio filter is used for imaging oversized maps.
The image capture area is illuminated by two daylight balancedfluorescent
Videssence
ICELITE 360 light banks. Maps are held in place during imaging by
a vacuum easel. All of the images are captured by and processed
on a Macintosh Apple G4 (1 GHz with 1 GB RAM) computer operating
under OS 10 with OS 9 subroutines for optimal performance of Phase
One imaging software. Final quality control is performed under Adobe
Photoshop. And, LizardTech
SID Workstation (GUI interface) encoder is used for the creation
of SID images. The University of Florida also runs the LizardTech
DjVu Workgroup encoder.
The University of South Florida's equipment is a PhaseOne
PowerPhase digital
camera back with a 7000 pixel by 7000 pixel 24-bit color capture
capacity. The camera back is mounted on a Hasselblad
501CM camera, mounted on a SuperRepro copy stand. The camera is
equipped with 50 mm & 80 mm lenses. The image capture area is
illuminated by a Videssence
Koldlite 120V (K110-255BX) fluorescent light kit. All of the images
are captured by Phase One imaging software. Final quality control
is performed under JASC PaintShop Pro and ImageRobot. And, LizardTech
SID Workstation (command-line interface) encoder is used for the
creation of SID images. The University of South Florida also runs
the LizardTech DjVu Solo encoder.
RESOURCE DESCRIPTION : Structural Metadata
A file of structural metadata is created for every map to indicate
the relationship between the physical units of digitization (TIFF
master, JPEG thumbnail, and SID image). The metadata format used is
currently the Florida Center for Library Automation's Metadata
eXchange Format (MXF), which will soon be replaced by the Metadata
Encoding & Transmission Standard (METS).
IMAGE LOADING and RETRIEVAL
Map images and their descriptions are loaded into the Visual Collections server at FCLA, which is an application of the XPAT search engine and Image Class middleware available through the University of Michigan's Digital Library Extension Service (DLXS). Map descriptions are stored as indexed SGML files.
In addition, persistent URLs referencing the server application are created by
program and inserted into the bibliographic record describing the
resource in the library catalog.
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