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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