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Image capture standards
The following image capture standards are used by the National Library in digitisation of its collection material. All digital master images are saved as uncompressed TIFF files.
| 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 48 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 |
300 ppi at 100% |
| Print publications scanned for Copies Direct orders | Bi-tonal (or RGB where the copy would be illegible if scanned as bi-tonal image) | 300 ppi at 100% Multi-page TIFF format |
NB* The resolution given is based on the optical capabilities of the scanning device, not interpolated resolution.
