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NLA Digital collections: Statement of Preservation Intent
Collection Area: Newspaper Digitisation
The NLA newspaper Digitisation Program has captured content predominantly from pre-1954, microfilmed Australian Newspapers, and to date includes some Journals content (e.g. Australian Womens Weekly 1933-1982). In the near future Journals will mostly be digitised via the NLA Books and Journals Workflow.
For the following outputs for the Newspaper Digitisation Program, Digitisation and Photography Branch intends that:
- All digital preservation masters, including metadata, will be kept until an alternative (better version) is captured. Currently materials designated as masters includes high resolution greyscale and Bitonal TIFFS which have different roles – The Greyscale masters are used as the preservation masters and for creating derivatives for access whereas the Bitonal co-master (derived from the Greyscale master) is used for creating XML METS, XML ALTO and other derivatives. Currently both master files should be retained. However, the use of Greyscale and Bitonal files will be reviewed when NCM is re-developed under DLIR in 2015, presumably in light of decisions that have been made for the re-development of the DLIR Books & Journals Project and other international best practice. For example, as technology becomes better, will the NLA require Bitonal co-masters in the future?
- Derivative files created for access should be maintained only for as long as useful; when no longer useful, a new derivative version should be generated. For example, derivative:
- (tiles and thumbnails) created from the Bitonal co-master for QA purpose. Delete after QA process.
- Derivative (tiles and full view) for access (.JPEG). Created from Grayscale master and need to be kept as long as the access technology is current after which they may need to be replaced with a new derivative as required.
- Derivative for access (.PDF). Created from Greyscale master and need to be kept as long as the access technology is current after which they may need to be replaced with a new derivative as required.
- Derivative metadata includes:
- METS metadata descriptor file describing the structure of the item which is generated from the Bitonal co-master (and stored in a SQL database) that is generated by contractor maybe re-captured overtime and replaced by new version when the master file is replaced.
- xml ALTO descriptor file (paragraphs, line breaks, bounding box co-ordinates of each word, fonts/styles picked up by the OCR engine) of an item generated from Bitonal co-master (and stored in a SQL database) that are generated by contractor will have to be re-captured overtime and replaced by new version when the master file is replaced. The page, article and Issue relationships are recorded in the XML ALTO file. This along with the XML METS file should be considered as a single intellectual entity to record structure for access purposes.
- Master Images and OCR deliverables originating from outside the NLA digitisation program should be treated in the same way as internally generated content for digital preservation.
- Master material might be recaptured over time, though currently there is not routine process to replace images with better quality images. However, the replacement of redundant master image with new master files and newly generated derivatives creates a problem, i.e. what to do with the content in the enhanced derivatives which may have already been corrected, tagged or had comments added. Similarly, replacing or inserting pages that have linkages to other pages through continuing articles is currently not possible without replacing the whole issue.
- The deterioration of the source may affect future re-digitisation efforts. By far the bulk of image content has been captured from microfilm. This material as well as the original print media will continue to deteriorate after the digital copy was captured. Therefore, it is important that the digitised surrogate is the best possible quality.
- Whether creating a digital surrogate of the microfilm or an original analogue material is an appropriate digital preservation strategy is a preservation reformatting rather than a digital preservation issue.
The Text correction and Tagging metadata (layers) in TROVE that is done by the User community is the responsibility of the TROVE team. The maintenance of this enhanced derivative metadata will need to be considered in the context of both changes to both the TROVE and Newspapers Digitisation systems and changes that occur if re-digitisation is required.
Version 1.1 15 July 2013