Digital capture and image creation - standards and equipment
Digital capture standards
Digital master images are saved as uncompressed TIFF files. The following tonal and spatial resolutions are applied at capture (resolution is based on the optical capabilities of the scanning device and not interpolated resolutions).
| Material type | Tonal resolution (pixel depth) | Spatial resolution |
|---|---|---|
Colour reflective formats, including:
|
RGB 24 bits per pixel |
Larger than A5: 300 ppi Smaller than A5 but larger than A6: 600 ppi Smaller than A6: 1200 ppi |
| Colour transparencies, including 35mm | RGB 24 bits per pixel |
2000 ppi |
| Colour negatives, including 35mm | RGB 48 bits per pixel |
2000 ppi Note: two digital masters are created: colour negative and colour positive; derivatives are created from the colour positive. |
B&W reflective formats, including:
|
RGB 24 bits per pixel |
Larger than A5: 300 ppi Smaller than A5 but larger than A6: 600 ppi Smaller than A6: 1200 ppi |
| B&W negatives 35mm | Greyscale 16 bits per pixel |
3000 ppi (TIFF master and derivatives positive) |
| B&W negatives larger than 35mm | Greyscale 16 bits per pixel |
2000 ppi (TIFF master and derivatives positive) |
| B&W microfilm masters of newspapers (for the Australian Newspapers Digitisation Program) | Greyscale and bi-tonal (image optimised for OCR) |
400 ppi |
| Print publications | RGB 24 bits per pixel |
150 ppi at 100% |
Digital capture equipment
The Library makes use of a variety of digital capture devices, including flat bed scanners, film/slide scanners, microfilm/microfiche scanners and digital cameras. Three kinds of devices are used by the Digital Collections Management Branch team for image capture, as listed in the table below.
| Type of device | Devices used |
|---|---|
| Digital cameras |
|
| Film & slide scanners |
|
| Flat bed scanners |
|
| Microfilm/microfiche scanners |
|
The nature of the material to be digitised, particularly its condition and construction, determines the type of equipment used for capture. All collections are surveyed prior to digitisation and minimal handling during the digital capture process is preferred.
Digital capture software
Images are scanned using oXYgen Scan v.2.6.1 and LaserSoft Imaging®'s SilverFast Ai scanner software. Captureshop software is used for the Sinar cameras and Capture One and Digital Photo Professional software are used for raw conversion. Adobe PhotoShop® is used for image processing (eg image rotation, cropping and manipulation).
Guidelines for the selection of the digital capture device
Items are individually assessed but the following general guidelines apply to the selection of the digital capture device.
Flat bed scanners are used for items less than A3 in size (420x297 mm), such as:
- printed music: unbound sheet music
- printed material, including single sheets (eg handbills, newspapers, posters); ephemera (eg brochures, tickets); single section pamphlets or other bound items that can be opened with ease
- manuscripts: single sheets in pencil or ink (letters, etc), small printed items
- maps in good condition
- artworks on paper:
- hand and mechanically produced prints in black ink with no added colour or extreme relief (eg engravings, etchings, lithographs)
- pen and ink drawings without watercolour or gouache additions (eg cartoons)
- photographic material: film negatives, transparencies, microforms, glass negatives and lantern slides (eg in a scanner with pull-out drawer), B&W and colour gelatin silver prints, albumen prints
Film/slide scanners are used for:
- strip films, negatives and transparencies
- mounted slides
Digital cameras are used for:
- fragile items
- oil paintings
- most original artworks on paper (eg watercolours, drawings)
- artwork with loose, friable media (eg pastels, charcoal, crayons, soft pencil)
- watercolours with thick paint, gouache or glazes
- loose pages, sheets from albums of printed items
- items larger than A3 or oversize (eg posters)
- bound volumes: books, albums, printed music, atlases
- maps: large or fragile maps, river maps, maps with colour
- manuscripts: bound diaries, letter books, folded items, large items
- documents on parchment and vellum
- photographic items: oversize B&W and colour prints; historic process photographs (eg daguerreotypes, ambrotypes); platinum prints and other non-silver prints; glass negatives and lantern slides (if not possible to scan on a flat bed scanner)
- three dimensional material: textiles, sculpture, objects, wax seals and realia
