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- Avoid overly light or overly dark scans. Use the preview feature of your scanner to inspect the tonal range (histogram) of the scanned images. Adjust the scanner settings if the histogram indicates that light or dark areas are being badly clipped (crashing into the end of the range, see reference).
- High-quality (low compression) JPEG files are recommended for archival. For an 8 to 16 megapixel image, a high quality JPEG will typically require from 4 to 10 megabytes of disk storage. JPEG compression is independent of scan resolution and it is determined by a quality setting (usually 0-100) offered by your image processing software when you save the JPEG file. A quality setting of at least 90 is recommended.
- TIFF and other uncompressed formats are okay, but not required or recommended. TIFF files are several times larger than JPEG files, without clear benefits in quality for our use.
- Original scan files (especially JPEGs) should be treated as "digital negatives" and never overwritten. For editing, make a copy of the original and edit the copy. This eliminates a key concern about using JPEGs--that repeated overwriting will degrade image quality. (If you need to make several editing passes on an image, save your intermediate copies as TIFF files. See reference.)
PDF Finding Aids
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