American Environmental Photographs, 1891-1936

Building the Digital Collection

The University of Chicago Library received an award in the 1996/97 round of the Library of Congress / Ameritech National Digital Library Competition to support the digitization of this collection of photographs of the environment. As encouraged by the guidelines, the image files are mounted and maintained at the University of Chicago. Descriptive bibliographic records were delivered to the Library of Congress for indexing as part of American Memory. Each record includes links to the corresponding image files.

Digitizing the Collection

Original media (glass lantern slides, glass negatives and photographic prints) were scanned by project staff at the University of Chicago Library using an Agfa Duoscan 8.5" x 14" flatbed scanner with a transparency adapter. Original scans were captured at 600 dpi, 8-bit grayscale. Quality control was accomplished by inspecting the images on screen for skew and image quality. The high resolution uncompressed TIFF files are written to CD media for long term storage. Using Debabelizer software, two access images were derived from each file: a high resolution JPEG compressed image measuring approximately 875 x 650 pixels for reference, and a GIF image for display with the bibliographic record on the American Memory site. More than 90 percent of these derived images were created in batch mode using Debabelizer scripts. Because of the variation in size among the photographic prints they were processed in smaller batches and a few prints were scaled individually.

Cataloging the Collection

The database of bibliographic records that support access to the images was constructed using Microsoft Access to create a table with forty-six data fields. The fields included caption, photographer, slidemaker, date of original photograph, subject terms and a unique identifier. Descriptive information input into the database was taken from the slide labels, fronts and backs of photographic prints, glass negative sleeves, notebooks and photographic print albums.

Subject authorities used were Library of Congress Subject Headings, the Thesaurus for Graphic Materials of the Library of Congress Prints and Photographs Division (LCTGM) and the Art and Architecture Thesaurus (AAT (external link)) of the Getty Research Institute. Supplementary authorities include A Glossary of Geographical Terms, edited by Dudley Stamp and Audrey Clark, London: Longman, 1979 and Encyclopedic Dictionary of Physical Geography by Andrew Goudie, et al, Oxford: Basil Blackwell, 1985.

Three online services expedited locating authoritative terms for plants and geographic names:

Interoperability between the Library of Congress and the University of Chicago

The descriptive metadata for the American Environmental Photographs was extracted directly from the Access database of bibliographic records using SQL and ODBC and converted into SGML using a Python program according to a locally written Document Type Definition (DTD) for the data. The converted data was run through an SGML validator before being shipped to the Library of Congress. The records were transformed automatically at the Library of Congress to facilitate indexing by the InQuery search engine and to allow records for this collection to be distinguished from other American Memory collections.

Individual image descriptions are displayed through American Memory with a thumbnail of the image; clicking on the thumbnail invokes delivery of the higher resolution image. The image files are maintained on University of Chicago Library servers. The images are accessed from the bibliographic description via a unique identifier which forms part of the address for the image. The unique identifier has been constructed for each image by using a combination of letters and numbers to represent the project name, state, medium and accession number. The name of the electronic collection is American Environmental Photographs, abbreviated AEP. Two-letter postal abbreviations identify each state. The letters S, N and P indicate slides, negatives and photographs respectively and the accession numbers begin with 1 and continue as needed for each subset of images. An example of an image identifier is AEP-ALS10, which stands for the American Environmental Photographs Collection, Alaska, slide format, image number 10.