Bookscanners
Many bookscanners are in use today, including proprietary, custom-built systems for mass digitization initiatives (e.g., Open Content Alliance, Google). In November, 2002, the Weissman Preservation Center and HCL Preservation & Imaging Services posted the following functional requirements to our web site. We still apply many of these criteria when evaluating bound-volume scanning equipment and services.
REQUIREMENTS
Non-damaging, affordable imaging of bound materials is a decades-old challenge in photography. Systems and workflows must be configured to meet requirements for binding support, page support and page turning, image quality, and speed. All solutions rely foremost upon the engineering of the book cradle—whether it is an integrated feature of the imaging system or a separate component.
Book cradles fall into two general categories: those that require volumes to be opened fully to 180°, and those that permit volumes to open at angles between 90° and 180°. Cradles and bookscanners in the latter category are preferred for imaging historic materials, particularly rare books and other objects governed by handling policies that disallow the use of flat-platen imaging systems (photocopiers, flatbed scanners, and cradles that require 180° openings).
The capabilities of bookscanners vary in the following categories:
- cradle design
- methods to hold pages in place and to turn pages
- size limitations for the volume
- flexibility and adaptability (e.g., for lens and lighting configurations)
- digital output (bit depth of images, noise, resolution, metadata)
- speed (particularly exposure time)
- rescan rates
- pricing, and extent of service and support
A silver-bullet solution?
Given the range of book types and of output requirements in library digitization workflows, there is not a mandate for a one-size-fits-all system.
When quality is paramount, solutions exist. See, for example, reports from the Digital Gutenberg Project, and the Early American Fiction Project. The complex digital photography systems for Gutenberg and EAF, like the studio cameras and cradles that preceded them, depend upon skilled photographers and achieve modest throughput (ca. 20-100 images per day).
When production is paramount, and quality must be adequate, there continues to be a need for system development. (The exclusive use of page scanners and microfilm scanners to meet the production demands for JSTOR, Making of America, and other high-volume workflows provide evidence to support this claim.)
Proposed requirements for a production system
What are the requirements for a production system? One might begin with the criteria satisfied by microfilm camera workstations and workflows:
- to integrate the use of a 180° cradle with appropriate configurations for safe handling of boards, spine and pages
- to accommodate books at least 12" wide (two-page spread), and up to 20" wide
- to produce grayscale output, with minimal noise
- to achieve sufficient detail reproduction (according to Quality Index or other metric) for text legibility in a 1:1 printed output
- by optimizing lighting and ergonomics for page-turning, focus and exposure controls, to allow an operator to achieve a throughput of 2,000-3,000 pages per day (1,000-1,500 exposures, ca. 200-250 exposures per hour)
- to be relatively easy to use
- to be reliable and robust, meeting production demands for years of service