Archiving Standards
The following information guide has been generated to assist faculty and staff in the slide and image digitization process.
The visual resources in the online Westphal Slide Library will be accessible to numerous users. Therefore we ask that collection material be submitted with adherence to our standardized archiving process.
Following our archive standards has many benefits including:
- Improved image quality
- Image size consistency throughout your collection
- Easy migration to our database
- Image resizing and modification can be left up to the individual user after the archived image is downloaded from the archive to the local users drive.
The standard archiving recommendation for slides is as follows:
Resolution: 2400
File Format: TIFF
Image Compression: NONE
Pixel Order: Interleaved
Byte Order: IBM PC
Please note: Each slide image file size will be roughly 23mb.
Key Terms for Understanding Digital Image Archiving
- Resolution: The sharpness and clarity of an image. Usually expressed as the density of elements, such as pixels, within a specific area. A higher resolution means more image detail.
- TIFF: Tagged Image File Format. TIFF has the ability to store images data in a lossless format that is ideal for image archiving. TIFF files can be edited and resaved without compression loss (unlike JPEG).
- Lossless data compression: a class of data compression algorithms that allows the exact original data to be reconstructed from the compressed data. This can be contrasted to lossy data compression, which does not allow the exact original data to be reconstructed from the compressed data.
- Dots per inch (dpi): DPI is often mistakenly used to describe a scanners optical resolution. In fact, dots per inch is a measure of printing resolution. Scanners use samples per inch but most consumers are more familiar with understanding image resolution by dots per inch and therefore the term is commonly misused.
- Samples per inch (spi): The measurement of the resolution of an image scanner; the number of individual samples that are taken in the space of one inch. For example, a 1200 dpi scanner takes 1200 color samples per inch. Flatbed scanners usually include a “maximum” resolution (often 9600) which is misleading because a 1200 dpi optical scanner is not capable of 9600dpi. Instead, the scanner uses interpretive resolution software to increase the image's resolution. Consequently, use of a resolution setting higher than the scanner's optical resolution (e.g., 1200) can result in image blurring.
For more information about digital image reproduction feel free to visit:
The Getty Introduction to Imaging
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For a printable .pdf version of these standards, click here