Over the course of its one-hundred-year existence, the Prints & Photographs Division has used a variety of methods for providing access to its holdings, ranging from placing images in file cabinets for direct browsing by researchers to making representations of the original images accessible online through sophisticated indexing and digitization schemes.
In devising these methods of access, staff members have kept in mind researchers' interests in:
Researchers familiar with cataloging practices in libraries, archives, and museums will recognize that, just as the division holds materials characteristic of all of these kinds of repositories, its access systems have partaken of methods from all three worlds.
Therefore, the division's access systems do not lead comprehensively to all subjects and artists or, especially, photographers represented in the collections. Indirect methods are sometimes helpful in locating subjects and creators. For collections that are indexed primarily by subject, it may be necessary to search under subjects that an unlisted photographer or artist was known to have covered and to examine the materials themselves for credits and attributions. Conversely, in collections indexed primarily by artist's name, it may be necessary to research artists known to have depicted a particular subject in order to find pictures relating to that topic.
Because of the emphasis on subject matter in many of the division's access tools, staff members have, over the years, put considerable effort into devising subject indexing schemes suited to its collections. The division attempts to match the rest of the Library's indexing for names of people, organizations, and places. When it comes to topical terms, however, many of the terms and conventions used in the Library of Congress Subject Headings (LCSH), which were originally intended for indexing the subjects of books, are not well suited to pictorial materials. Some commonly depicted concepts, like “Shotgun weddings” or “Children playing adults,” are too specific to be included in that general list.
In an effort to fill these gaps, Prints & Photographs Division cataloging specialists extracted the most appropriate terms from LCSH and other subject heading lists and supplemented them with additional terms as needed in the course of cataloging. Headings used in several reading room files and card indexes are derived from a preliminary list issued in 1980, Subject Headings Used in the Library of Congress Prints and Photographs Division, by Elisabeth W. Betz, which is available in notebooks near the files in which the terms are used, to help researchers identify appropriate headings. A new thesaurus, better suited to the capabilities of computer indexing and adhering to thesaurus guidelines for expressing relationships among terms, was published by the division in 1987 and is continuously updated. The LC Thesaurus for Graphic Materials, the source of topical terms for most of the collections in the Prints & Photographs Online Catalog, is available through the catalog to help researchers narrow and expand their searching.
Research involving pictorial materials is concerned not only with who made the materials and what they depict, but also with the pictorial processes and formats they employ and the genres they represent. You may wish to concentrate on images produced as "postcards," "magazine covers," "fruit crate labels," "fashion plates," or "cartoons," or to focus on a particular type of portraiture, such as "group portraits," or a specific print process, such as "etchings." The LC Thesaurus for Graphic Materials also includes these genre and format terms, helping indexers and researchers locate terms for such categories of pictorial material. Although these terms appear sporadically in some of the division's older card catalogs, they are most useful for searching material indexed in the online catalog.
The Thesaurus for Graphic Materials does not include proper names of people, places, and events that are the subjects of pictures. For those, catalogers rely on library authority files (e.g., the Library of Congress Name Authority file and the Library of Congress Subject Headings) and other tools to enable them to standardize references to names.
As more and more metadata (descriptions and index terms) becomes available online, researchers are seeing the potential for analyzing large bodies of information to draw conclusions about artistic practices, image usage patterns, and cultural trends. When analyzing a body of metadata, it is important to understand who compiled it, based on what sources and conventions. Many of the collections accessible through the Prints & Photographs Online Catalog (PPOC) include a section on "Cataloging the Collection" that outlines the practices staff followed in compiling the metadata. Staff are also happy to assist researchers in gathering this information when it is not evident.