Anne Kenney will focus on some of the issues surrounding direct scanning as identified in the Cornell Xerox Project. Among those to be discussed are: image versus text capture; indexing and access; image-capture capabilities; a comparison to photocopy and microfilm; production and cost analysis; storage formats, protocols, and standards; and the use of this scanning technology for preservation purposes.

The 600-dpi digital images produced in the Cornell Xerox Project proved highly acceptable for creating paper replacements of deteriorating originals. The 1,000 scanned volumes provided an array of image-capture challenges that are common to nineteenth-century printing techniques and embrittled material, and that defy the use of text-conversion processes. These challenges include diminished contrast between text and background, fragile and deteriorated pages, uneven printing, elaborate type faces, faint and bold text adjacency, handwritten text and annotations, nonRoman languages, and a proliferation of illustrated material embedded in text. The latter category included high-frequency and low-frequency halftones, continuous tone photographs, intricate mathematical drawings, maps, etchings, reverse-polarity drawings, and engravings.

The Xerox prototype scanning system provided a number of important features for capturing this diverse material. Technicians used multiple threshold settings, filters, line art and halftone definitions, autosegmentation, windowing, and software-editing programs to optimize image capture. At the same time, this project focused on production. The goal was to make scanning as affordable and acceptable as photocopying and microfilming for preservation reformatting. A time-and-cost study conducted during the last three months of this project confirmed the economic viability of digital scanning, and these findings will be discussed here.

From the outset, the Cornell Xerox Project was predicated on the use of nonproprietary standards and the use of common protocols when standards did not exist. Digital files were created as TIFF images which were compressed prior to storage using Group 4 CCITT compression. The Xerox software is MS DOS based and utilizes off-the shelf programs such as Microsoft Windows and Wang Image Wizard. The digital library is designed to be hardware-independent and to provide interchangeability with other institutions through network connections. Access to the digital files themselves is two-tiered: Bibliographic records for the computer files are created in RLIN and Cornell's local system and access into the actual digital images comprising a book is provided through a document control structure and a networked image file-server, both of which will be described.

The presentation will conclude with a discussion of some of the issues surrounding the use of this technology as a preservation tool (storage, refreshing, backup).

Pamela ANDRE and Judith ZIDAR

The National Agricultural Library (NAL) has had extensive experience with raster scanning of printed materials. Since 1987, the Library has participated in the National Agricultural Text Digitizing Project (NATDP) a cooperative effort between NAL and forty-five land grant university libraries. An overview of the project will be presented, giving its history and NAL's strategy for the future.

An in-depth discussion of NATDP will follow, including a description of the scanning process, from the gathering of the printed materials to the archiving of the electronic pages. The type of equipment required for a stand-alone scanning workstation and the importance of file management software will be discussed. Issues concerning the images themselves will be addressed briefly, such as image format; black and white versus color; gray scale versus dithering; and resolution.

Also described will be a study currently in progress by NAL to evaluate the usefulness of converting microfilm to electronic images in order to improve access. With the cooperation of Tuskegee University, NAL has selected three reels of microfilm from a collection of sixty-seven reels containing the papers, letters, and drawings of George Washington Carver. The three reels were converted into 3,500 electronic images using a specialized microfilm scanner. The selection, filming, and indexing of this material will be discussed.

Donald WATERS