In the use of electronic imaging for document preservation, there are
several issues to consider, such as: ensuring adequate image quality,
maintaining substantial conversion rates (through-put), providing unique
identification for automated access and retrieval, and accommodating
bound volumes and fragile material.
To maintain high image quality, image processing functions are required
to correct the deficiencies in the scanned image. Some commercially
available systems include these functions, while some do not. The
scanned raw image must be processed to correct contrast deficiencies--
both poor overall contrast resulting from light print and/or dark
background, and variable contrast resulting from stains and
bleed-through. Furthermore, the scan density must be adequate to allow
legibility of print and sufficient fidelity in the pseudo-halftoned gray
material. Borders or page-edge effects must be removed for both
compactibility and aesthetics. Page skew must be corrected for aesthetic
reasons and to enable accurate character recognition if desired.
Compound images consisting of both two-toned text and gray-scale
illustrations must be processed appropriately to retain the quality of
each.