Term: Microfilm standards
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Term: Microfilm standards
- Libraries and archives standardized microfilming practices during the latter third of the twentieth century. The Library of Congress published two guidelines in the 1970s, followed by the publication of a number of standards in the decades that followed. (Slightly out of date references to these standards will be found on Web pages provided by OCLC and the Library of Congress.) Many of these standards were first developed under the auspices of ANSI and AIIM, and today they are being extended and integrated under ISO auspices.
The following standards are especially relevant to those who wish to evaluate existing microfilms for digital scanning:
• ANSI/AIIM MS23-2004. Standard Recommended Practice - Production, Inspection, and Quality Assurance of First-Generation, Silver Microforms of Documents
• ANSI/AIIM MS111-1994. Micrographics - Standard Recommended Practice for Microfilming Printed Newspapers on 35mm Roll Microfilm
• ISO 6199:2005. Micrographics -- Microfilming of documents on 16 mm and 35 mm silver-gelatin type microfilm -- Operating procedures.
• ISO 6200:1999. Micrographics -- First generation silver-gelatin microforms of source documents -- Density specifications and method of measurement.
ANSI/AIIM standard MS23 was first published in 1979 and has seen several revisions, the most recent in 2004. For many years, it has been the central document for the field. ISO standards 6199 and 6200 incorporate many of MS23's specifications. ISO's Web site describes standard 6199 as specifying (1) "procedures that enable a camera operator to produce microfilm of appropriate quality of presentation and legibility, capable of yielding scanned images of acceptable quality" and (2) "methods for microfilming documents on 16 mm and 35 mm silver-gelatin microfilm, including orientation of images on microfilm, use of non-image areas and information required to facilitate identification of the microfilm."
Digital scanning will produce better results when the selected microfilms meet or exceed the specifications in the preceding standards. It is the case, of course, that some films produced prior to the publication of these standards may conform to them, in whole or in part. Several desired specifications and related factors are cited by the National Digital Newspaper Project in a technical bulletin (p. 5) for participants planning to scan microfilm:
• high quality capture, avoiding or minimizing page curvature, gutter shadows, or lack of focus
• lower reduction ratios (below 20x) preferred to higher
• the inclusion of test charts in which resolution test pattern 5.0 or higher is readable
• unambiguous indication of reduction ratio
• variations in density between images and exposures narrower than permitted by current standards, i.e., from 0.9 to 1.2
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