These standards reflect SIA requirements for digitization of images. These standards reflect available best practices applied in the context of SI Archives resource constraints at a specific point in time.
TIFF files in Intel (PC) byte format.
||TIFF 24 bit, RGB
||TIFF 8 bit
Notes: Sepia-toned images should be digitized using Color format specifications. Grayscale preferred for non-color images.
- 6,000 pixels along the long axis of an image.
- No less than 600 dpi to yield a minimum of 6,000 pixels along the long axis. For images more than 10 inches in length, resolution should be set to 600 dpi.
- Increase dpi setting by intervals of 25 in order to achieve a minimum of 6,000 pixels on the long axis.
To determine proper resolution, measure the actual item along the longest dimension, rounding to the half inch. Increase the dpi setting by intervals of 25 dpi as necessary to achieve the minimum required pixelation.
For example, an image 11 inches long that is digitized at 600 dpi will exceed the 6,000 pixel minimum and is therefore acceptable. A 6 inch long item will require 1000 dpi to meet the 6,000 pixel requirement.
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All items of similar dimension within an accession series will use a common resolution setting.
All items of similar color profile within an accession series will use the same color profile. A series which contains 2 or more color profiles, e.g., grayscale and color, will batch items according to color profile.
Batches will consist of items from within a single record series, preferably from within (or limited to) a single folder of that series. Batches must be internally uniform with regard to format and resolution.
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REFLECTIVE IMAGES - VERSO
When the back (verso) of reflective images (e.g., photographs) contain annotations, drawings, or other significant markings, the backs should be digitized as well. Format should be grayscale with resolution set at 200 dpi unless two or more colors are present.
Testing shall be conducted on each batch. To facilitate quality verification, the applicable ICC profile settings and calibration guide should be captured as part of each batch.
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Images are stored redundantly on DVD-R/DVD+R format optical media with a minimum of 2 offline copies: a preservation ‘master’ and a preservation ‘backup’. DVD-R/DVD+R are recognized "Write-Once-Read-Many" formats which ensures the integrity of the files placed on that disk.
An additional set may be created for reference/public access which may exist online, if permissions/rights issues and internal policies allow. The preservation master DVD disk is to be stored in appropriate offsite archival storage. Technical information regarding creation date of the disks and software used for disk creation is to accompany the disks.
Digitization projects with preservation master storage requirements over 250 gigabytes should consult with the SIA IT Archivist for preferred storage medium details.
No labels are to be affixed directly to the DVD disk. No markers are to be used to label the DVD disk. Both of these activities have been proven in national studies to degrade the archival life of the DVD.
DVD disks are to be stored in ANSI certified inert sleeves separately from paper and in an upright position. Labels are to be affixed to the outside of the sleeve to avoid direct contact with the disk.
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