Preservation of Digitised Books in a Library Context

The focus of this paper is on which digital objects to preserve when preserving digital library materials derived from original paper materials. It will investigate preservation strategies for digital objects from digitised paper material that must both be preserved and simultaneously retain a short route to dissemination. The investigation is based on a study of digitisation done a decade ago and digitisation done today.
In the last decade mass digitisation has become more commonly used since technological evolution has made it cheaper and quicker. The paper explores whether there are parts of digital material digitised a decade ago worth preserving, or whether a re-digitisation via mass digitisation today can create a relevant alternative.
The results presented show that the old digitised objects are worth preserving, although new digitisation can contribute additional information. A supplementary result is that investment in digitisation can mean lower costs in the long term. Manual adjustments for the image processing can result in considerably smaller images than images made in cheap mass digitisation. Although initial manual work is more expensive, the storage and bit preservation expenses are lower over a long period.