Digitisation of traditional format library materials

Images for web delivery

See also: Digital Collections

The size of the images impacts on the uniform presentation of the search results. It also affects the speed at which pages are loaded to a user's web browser which is important when network bandwidth is an issue, as it is for many geographically remote users.

Digital masters of all items digitised are saved on the National Library's local system in Tagged Image File Format (TIFF). The following range of derivatives are produced from the TIFF masters (unless otherwise specified) for convenient web delivery:

Master (TIFF):
  • Created for all material formats
  • Resolution: 300-2000 ppi depending on the original item
  • Uncompressed
  • RGB colour
  • 24 bits per pixel
Co-master (TIFF):
  • Created as required from TIFF master for any material format
  • Resolution: 300-2000 ppi depending on reason created
  • Compressed - Lempel-Ziv Welch (LZW)
  • 24 bits per pixel
Thumbnail copy (JPEG):
  • Derived for all material formats from TIFF master
  • Resolution: 72 ppi
  • Longest dimension: 150 pixels (eg 118x150 portrait; 150x118 landscape)
View copy (JPEG):
  • Derived for all material formats from TIFF master using Image Alchemy software
  • Resolution: 72 ppi
  • Longest dimension: 600 pixels for pictures and 760 pixels for manuscripts, maps and music (eg 590x760 portrait; 760x760 square; 760x590 landscape)
Examination copy (JPEG):
  • Derived for printed music and cartographic materials from TIFF master using Image Alchemy software
  • Resolution: 72 ppi
  • Longest dimension: 1000 pixels (eg 781x1000 portrait; 1000x1000 square; 1000x781 landscape)
Print copy (PDF):
  • Derived for printed music from JPEG examination copies using Image Alchemy software
  • Compressed
  • Resolution: 72 dpi
  • Longest dimension: 1000 pixels
Interactive copy (MrSID):
NB* A MrSid derivative may be produced for any format material where there is a demonstrated need to reveal fine detail
  • Created for cartographic material from TIFF master using MrSID software
  • Compressed
  • Resolution: 300 ppi
  • Longest dimension: As per the TIFF master (varies according to the original physical item)

NB* The shorter dimension is set to whatever is appropriate to maintain the aspect ratio of the image.

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