Preservation Digitisation Standards

This document provides the standards for the digitisation of physical records to ensure the preservation, security and usage of data in accordance with AMI’s digital repository policy and digital preservation guidelines. 

The aim is to provide a digitised replication (a digital surrogate) of the physical records for long-term preservation and sharing.

The following table lists the ideal digitisation standards with an understanding that minimum acceptable standards will also be adopted as needed for the digitisation of older, lower-quality audio or video materials.  AMI will also rely on the advice of external digital preservation contractors after they have examined the analogue originals and made recommendations for the best preservation formats.

These standards have been researched and developed in line with best international practice and prescribe the technical requirements, including preservation formats for paper-based text, images and audio-visuals. These standards should be reviewed on an annual basis to ensure that they remain in line with the standards of other international institutions.

Preservation digitisation reduces the physical wear and tear on fragile records and is an effective tool to preserve records at risk of being lost if they are held on unstable media or subject to technological obsolescence. Digitisation also allows for these records to be accessible to a wider, global audience and ensures that they are available in perpetuity.

The digital reproduction will:
•    capture a complete, accurate record of physical records.
•    be preserved and accessible into the future.
•    enable the reuse of the digitised content to meet future access requirements.
•    minimise the physical wear and tear caused by handling fragile materials.

In accordance with international standards, TIFF is the preservation file format for all non-audio-visual records, with JPEG and PDF file formats created for derivative versions for optional access and usage.  

For newly generated creative works and born digital materials we aim to follow the Library of Congress Recommended Formats Statement. These standards identify hierarchies of the physical and technical characteristics of creative formats, both analogue and digital, which will best meet the needs of all concerned, maximising the chances for survival and continued accessibility of creative content well into the future.

References:
https://www.ala.org/alcts/resources/preserv/minimum-digitization-capture-recommendations
https://siarchives.si.edu/what-we-do/digital-curation/recommended-preservation-formats-electronic-records
https://www.loc.gov/preservation/resources/rfs/TOC.html
https://www.naa.gov.au/about-us/our-organisation/accountability-and-reporting/archival-policy-and-planning/preservation-digitisation-standards

FormatFile typeCompressionResolutionBit depthColour space
Paper documentsTIFF 6.0Uncompressed400 ppi8 bit colour (24 bit)sRGB or Adobe RGB
Paper documents (primarily textual based)TIFF 6.0Uncompressed400 ppi8 bit colour (24 bit)Greyscale
Rare of significant documents, artwork, posters or large documents with a high level of detailTIFF 6.0Uncompressed600 ppi16 bit colour (48 bit)Adobe RGB or ProPhoto RGB
Bound volumesTIFF 6.0Uncompressed400 ppi8 bit colour (24 bit)sRGB or Adobe RGB
Bound volumes (primarily textual based)TIFF 6.0Uncompressed400 ppi8 bit colour (24 bit)Greyscale
Photographic prints and negatives smaller than A6 (10x15cm)TIFF 6.0Uncompressed2,700 ppi16 bit colour (48 bit)Adobe RGB or ProPhoto RGB
Photographic prints A6 to A4 (10x15cm to 21x30cm)TIFF 6.0Uncompressed900 ppi16 bit colour (48 bit)Adobe RGB or ProPhoto RGB
Photographic prints over A4 (over 21x30cm)TIFF 6.0Uncompressed600 ppi16 bit colour (48 bit)Adobe RGB or ProPhoto RGB
Photographic negatives and transparencies (up to 35mm)DNG (no cropping)Uncompressed5,000 ppi16 bit colour (48 bit)ProPhoto RGB
Photographic negatives and transparencies (up to 6x6cm)DNG (no cropping)Uncompressed4,000 ppi16 bit colour (48 bit)ProPhoto RGB
Photographic negatives and transparencies (6x6cm to 5”x7”)DNG (no cropping)Uncompressed3,000 ppi16 bit colour (48 bit)ProPhoto RGB
Photographic negatives and transparencies (5”x7” up to 8”x10”)DNG (no cropping)Uncompressed1,600 ppi16 bit colour (48 bit)ProPhoto RGB
MicrofilmTIFF 6.0Uncompressed4,000 ppi8 bitGrey Gamma 2.2
Audio (analogue)BWFEncoding: LPCMSampling frequency: 96 kHz24 bitAudio channel: same as original, rather than the recorded signal.
Audio (digital)BWFEncoding: LPCMSampling frequency: same as originalsame as originalAudio channel: same as original
Video[1] (high definition)MFX OP-1aMJPEG2000 lossless compression encoding

Frame size and rate: same as original

Audio stream: BWF

48 kHz, 16 bit PCM encoding

10 bit - VBRSame as original
Video (standard definition)MFX OP-1aMJPEG2000 lossless compression encoding

Frame size: PAL – 720 x 576, NTSC - 720 x 486

Frame rate: PAL – 25fps, NTSC - 29.97fps

Audio stream: BWF

48 kHz, 16 bit PCM encoding

 

Colour space: YUV

Chroma subsampling: 4:2:2

 


[1] For video digitisation the aspect ratio is to be the same as the original, there is accurate sync between audio and video, and that the preservation file copy displays the same interlacing as the original source tape.

Image
Maria Montessori, 1951, London, reading with children