Volume 21, Number 8
1997

Digital Projects at the University of Michigan

The University of Michigan Library is involved in a number of digital projects. Among these projects, those that focus on the conservation of brittle originals for the purpose of mounting the resultant electronic version on a Library website are managed in the Reformatting and Replacement Services (RRS) of the Preservation Division. The Division has the resources in place to offer conversion to digital format as one of the suite of options in its use-driven brittle books reformatting/replacement program.

We consider all digital images captured, processed and stored in our specifications--done either in-house or outsourced to a vendor--to be archival. All scanning is done at 600 dpi; images are stored as ITU Group 4 TIFF images (the ISO standard formerly known as CCITT Group 4 TIFF). Once quality control is completed, no post-capture manipulation is done on the images, making the online TIFFs a faithful representation of the printed original. The quality of the image seen by the user using current web browsers is an artifact of our web implementation, where our software does an on-the-fly TIFF to GIF conversion to enable the broadest possible viewing audience. The TIFF image stored by this Library is not altered. As the technology matures, it will be possible to deliver higher quality derivatives that more closely mirror the TIFF archival images resident on this Library's server. The platform-independent online images are stored on a RAID system which has a high degree of reliability; our backup images are on digital linear tape (DLT), which would be used to restore the files on RAID if necessary. The Library and the University are committed to providing enduring access to these images, with funding to support system maintenance and staff. The TIFF images will be migrated forward to new storage and access systems as necessary.

Intellectual access is further enhanced by OCR, resulting in a searchable text. While the electronic text derived from OCR is subject to error, that error rate is low enough to permit a detailed level of intellectual access. Further, as resources permit, we plan to edit the OCR'd text to more faithful conformance to the original. The Library's confidence in the archival quality of the digital images it creates, together with its--and the University's--commitment to enduring access, make withdrawing the original an acceptable alternative.

The decision to withdraw an original rests with the individual selector. The level of comfort with making withdrawal decisions--no matter what the format of the replacement--varies significantly. Analysis of 15 years of disposition decisions indicates that something less than 40% of brittle originals are withdrawn after reformatting into or replacement by a stable format copy. I do not for a moment believe that there will be a sudden rash of withdrawals of originals after conversion to digital format. However, I do believe that selectors will make the decision to withdraw the original that has been digitized at least at the same rate at which they currently withdraw the original that has been filmed. That rate may actually be higher, as the selectors will choose digital conversion knowing that the original will be disbound, and that there will be little chance it can be rebound.

This Library's participation in Making of America, Phase I, was designed from the start to retain the digital file and withdraw the original. A paper facsimile from the digital file will be printed only when a user requests that service. Staff directly involved with the project have had the time and opportunity to achieve a level of comfort with that project design. It will certainly be necessary to give to staff at all levels, in all units of the Library, the time and opportunity to find their own comfort levels.

To assist in the process, a working group has been pulled together from staff in the Preservation Division, Digital Library Programs, Systems Office, and selection staff to identify and analyze issues surrounding the use of digital files as a preservation medium and to recommend guidelines for the selectors. The guidelines will cover the decision to convert to digital format, and include the final disposition decision for the original. This group, the Digital Brittle Books Task Group (a.k.a. Brigital Books), will hold open discussions with, and conduct training sessions for, all selectors.