The Library of Congress / Ameritech National Digital Library Competition (1996-1999) | |
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Lessons Learned > Formats and Specifications for Digital Reproductions |
Several of the awardee institutions discovered that once they started to work with their particular content that they wished to change their initial plans for formats, resolutions, and conversion processes.
The team has determined that for this material, "150dpi color scans fully represent all significant data and are more than adequate for current monitor and printer standards." They argue that, based on experience from previous projects, the added costs associated with higher resolution versions (for processing and storage) are not justified by the likely level of usage. Users may request higher resolution scans of individual items.
"Images are saved as 150 dpi JPEGs with a high level of quality." 72dpi access copies and thumbnails are generated automatically using a locally developed combination of "the PERL language and freely available UNIX graphics software. This was a rewarding process which expanded the skills of the project manager and the Digital Scriptorium staff."
"The biggest problem encountered has been the prevalence of moiré patterns caused by halftone dots in the page being scanned. Most frequently these appear on the illustrated title pages, but are frequently found elsewhere in pieces as well. A variety of techniques from the imaging software were devised to deal with the issue."
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Content updated: 2002-11-18
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