Small-Town America, 1850-1920
Building the Digital Collection
The New York Public 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 selection from the Robert N. Dennis Collection of Stereoraphic Views. As encouraged by the guidelines, the image files and several of the web pages describing the source collection and the project are mounted and maintained at the New York Public Library.
Bibliographic records in the MARC format were delivered to the Library of Congress for indexing as part of American Memory. Each record describes a group of images and includes a link to the New York Public Library's presentation of that group of images. The presentation is generated dynamically from a database at the New York Public Library.
The Small-Town America site enables quick review of groups of similar and often repetitive images, such as landscapes and cityscapes; it also allows close examination of single items. Early in the digitization process, an analysis of research use led to the determination that three different file sizes were necessary to meet display objectives:
For Thumbnails, one half of each stereo card recto was scaled to 192 x 192 pixels or 192 x 178 pixels, depending on the size of the original. The stereo cards are usually about 3.2 or 4.2 inches high and about 7 inches wide.
The Display files, 504 pixels wide, allow viewers to see the recto of the full item about life-size in 24-bit color, but lack the detail to resolve imprinted texts or the minutiae of a landscape scene.
The Inspection files provide enlarged views. However, load-time for the initial color files was very slow offsite and navigation was unduly prolonged. To speed response time and navigation, the inspection files, 1024 pixels wide, were converted to grayscale. A corollary benefit was the increased on-screen legibility, for research purposes, of grayscale enlargements over color enlargements.
Archival images for the rectos were captured at 3072 x 1548 pixels or 3072 x 1865 pixels, respectively, and a set of printing files was generated by sharpening (level 3) and cropping out the grayscale and other margins up to 1/4 inch around the stereo cards.
The small, uniform format of stereoscopic views (32 x 7 inches and 42 x 7 inches approximately) meant that digital capture could be standardized somewhat and could progress quickly once parameters were determined. To ensure the ability to gauge the quality of capture, a grayscale target was required to be placed within the available margin of the image area. White and black specifications could then be checked using a program such as PhotoshopTM. An initial 1000 cards were delivered to allow for vendor ramp-up. This allowed New York Public Library to confirm specifications and productivity and to put in place a quality control program for subsequent deliveries. After confirmation of the specifications, the remaining stereo cards were shipped to the vendor by overnight air freight after being inventoried under the direction of the Photography Collection and packed by the Library's Conservation Division. The vendor was asked to deliver CDs in twelve batches of 1000 items each.
Quality control at New York Public Library consisted of confirming white/black levels within the grayscale, verifying file-names, identifying focus problems and noise interference, checking the labels on CDs and jackets, and testing the ability to open every CD and file through an image-viewing program.
The bibliographic records describing these stereo cards are collection-level MARC Visual Material cataloging records that were created during a two-year collection-processing and cataloging project funded by the National Endowment for the Humanities in 1989-1991. Each record describes a minimum of ten, and often many more, very similar items, for example, the same subject or location, perhaps taken by one photographer. Collection-level cataloging was deemed the most productive way to provide intellectual access to large quantities of similar visual materials because it was: economical in terms of the amount of resources expended per cataloged item, and efficient by containing very closely related items in one descriptive record. The records were created in RLIN (the Research Libraries Group cataloging system), edited and then uploaded into CatNYP, the online catalog of the Research Libraries of The New York Public Library.
The catalog records were downloaded to the database that underlies the New York Public Library's presentation of the overall collection. They were also transmitted to the Library of Congress.
The MARC catalog records, after some automated modifications, have been indexed using InQuery to allow full integration into American Memory. Bibliographic displays generated at the Library of Congress have links to the digital reproductions mounted at New York Public Library. To facilitate the linking to New York Public Library's presentation of each group of stereographs, the Library of Congress registered a handle for each group, using the RLIN number for each catalog record to generate a unique identifier. The handle was added to the catalog record along with local boilerplate fields to distinguish items in this digital collection from other American Memory collections.