Preservation

Textual and Microfilm

At NARA, the term “textual” usually applied to manuscript and typescript records. Examples include minutes of meetings, organizational charts, diaries, calendars, correspondence, reports, briefing books, legal opinions, directives, and publications.

In terms of digitization, general approaches to and specifications for image capture for maps and plans, architectural and engineering drawings, posters and other graphic materials are similar to those of textual records (manuscript and typescript documents).

Some of the characteristics of textual materials that may influence a digitization approach include whether the original is bound, a loose sheet, or rolled; size of original; condition of original; and type (high contrast or low contrast document, typed or handwritten, faded text or diffuse characters, etc.). Some of the parameters of textual documents that may be important to reproduce in the digital copy include legibility, sharpness, and ability to discern the smallest significant character.

Microfilm has several roles at NARA. For many years, it was the de facto preservation mechanism for many types of paper based records. Images were captured and output to microfilm via photochemical film-based process. More recently, this has evolved into a digital file-based workflow. Images are now captured digitally and stored as files. However, stable polyester-based silver-halide microfilm copies are produced from the digital files for two purposes. The first continues to support the historical success of polyester-based silver-halide microfilm as a stable preservation medium. NARA continues to output the highest quality file captured, either at the preservation or reproduction product level, to microfilm, which is then stored off site with the photochemically produced preservation masters. As our digital infrastructure matures, this workflow may be discontinued but there is no immediate plan to do so. The second option for microfilm production is a distribution option for fee requests for limited microfilm publications. Microfilm copies are available for Microfilm Publications beginning with the M, P. C, A or T prefix only. This Publication series have microfilm printing masters which are duplicated through a photochemical contact printing process. Microfilm can also serve as a source object for digitization projects. Some of the characteristics of microfilm that may influence a digitization approach or affect the quality of the resulting digital image include: text quality and clarity on the microfilm; the quality of the original capture of the film (lack of focus, uneven lighting, page curvature, gutter shadows, etc.); variations in density between exposures; the reduction ratio of the film (knowing what it is); resolution and the ability to detect detail on the film; and the condition of the film itself (scratches, etc.).

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