From the Florida Statewide Digital Action Plan: Guidelines for Building Good Digital Collections (2014) adopted from standards established by the American Library Association, Association for Library Collections and Technical Services (ALCTS).
The ALCTS Minimum Digitization Capture Recommendations states:
When digitizing objects one must be aware that different types of materials are used in different ways and that sometimes requires variations in the digitization specification. The Recommendations stated here should fulfill most needs, but may need to be adjusted to a higher specification in instances where the expected use is different than is described in this document.
Organizations should remember that digital objects are used in different ways and that this variety of uses needs to be considered in determining the level of digitization required. While the minimum level might meet most needs, an adjustment to the higher specification might be necessary for specialized needs.
Text
When scanning text documents, spatial resolutions should be based on the size of text found in the document and resolutions should be adjusted accordingly. Documents with smaller printed text may require higher resolutions and bit depths than documents that use large typefaces. Projects planning on applying Optical Character Recognition (OCR) may wish to test pages at several resolutions to find the most satisfactory results. Images that produce the best results for OCR may not be pleasing to the eye and may require separate scans for OCR and human display.
Projects with large amounts of textual materials, particularly hard-to-read materials such as manuscripts, should consider providing transcriptions of the materials in addition to the digital image. Access to textual material can be further enhanced through SGML/XML markup schemes such as the Text Encoding Initiative (TEI). As re-keying text can be cost prohibitive, projects considering transcriptions should investigate including Optical Character Recognition (OCR) software in their toolkit.
Text
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Master
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Access
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Thumbnail
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File Format
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TIFF
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JPEG
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JPEG
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Bit Depth
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1 bit bi-tonal
8 – 16 bit grayscale
48 bit color
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8 bit grayscale
24 bit color
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8 bit grayscale
24 bit color
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Spatial Resolution
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adjust scan resolution to produce a minimum pixel measurement across the long dimension of 6,000 lines for 1 bit files and 4,000 lines for 8 – 16 bit files
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150 – 200 ppi
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144 ppi
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Spatial Dimensions
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4000 – 6000 pixels across the long dimension
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600 pixels across the long dimension
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150 – 200 pixels across the long dimension
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Photographs
Photographs can present many scanning challenges. We recommend scanning from the negative (or the earliest generation of the photograph) to yield a higher-quality image. Another consideration is whether to scan sepia-tone photographs as color or black and white images. We recommend scanning them as color images to create a better image, although this will increase the file size. Another consideration with photographs is whether to scan the backs of photographs as separate image files if there is significant information on the back of the photo (which may be of interest to users) that may not be included elsewhere. If a scanned image of the verso of the photograph is available, the digital image may serve as a more successful surrogate for the original.
Photographs
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Master
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Access
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Thumbnail
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File Format
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TIFF
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JPEG
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JPEG
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Bit Depth
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16 bit grayscale
48 bit color
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8 bit grayscale
24 bit color
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8 bit grayscale )
24 bit color
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Spatial Resolution
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400 – 800 ppi
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150 – 200 ppi
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144 ppi
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Spatial Dimensions
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4000 – 8000 pixels across the long dimension, depending on size of original, excluding mounts and borders
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600 pixels across the long dimension
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150 – 200 pixels across the long dimension
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Graphic Materials
Graphics include the various techniques used to reproduce words and images from originals such as engraving, lithography, line art, graphs, diagrams, illustrations, technical drawings, and other visual representations. Nearly all graphics will be two dimensional, and should be scanned using the following guidelines.
Graphic Materials
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Master
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Access
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Thumbnail
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File Format
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TIFF
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JPEG
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JPEG
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Bit Depth
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16 bit grayscale
48 bit color
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8 bit grayscale
24 bit color
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8 bit grayscale
24 bit color
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Spatial Resolution
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600 – 800 ppi
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150 – 200 ppi
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144 ppi
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Spatial Dimensions
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6000 – 8000 pixels across the long dimension, excluding mounts and borders
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600 pixels across the long dimension
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150 – 200 pixels across the long dimension
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Artwork / 3 Dimensional Objects
For projects where the physical dimensions of the non-3D artwork match the equipment available, the following standards can be used. If scanning photographic copies of objects and artifacts, see recommended requirements in the appropriate photo and film charts. .
Artwork
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Master
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Access
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Thumbnail
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File Format
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TIFF
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JPEG
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JPEG
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Bit Depth
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48 bit color
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24 bit color
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24 bit color
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Spatial Resolution
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Device Maximum
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300 ppi
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144 ppi
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Spatial Dimensions
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100% of original
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600 pixels across the long dimension
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150 – 200 pixels across the long dimension
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Maps
Scanning maps may involve items that vary widely in size, condition, and amount of detail. Small maps may fit easily onto a flatbed scanner, but large plat maps may need to be scanned in sections, even on a large format scanner, or captured by a camera. The size of the image can become a problem for storage, but also for viewing, serving over the Web, or processing.
Smaller maps (less than 36 inches on the longest dimension) should be digitized at 600 ppi, 48-bit color or 16-bit grayscale if possible. For larger maps, 300-400 ppi may be more practical. If it becomes necessary to digitize a map in sections and stitch the image together in Photoshop, keep both the original images of the sections as well as the combined image. Stitching images together is very time consuming and can be difficult. Consider outsourcing the reformatting of large format maps.
Maps
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Master
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Web
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Thumbnail
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File Format
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TIFF
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JPEG
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JPEG
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Bit Depth
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16 bit grayscale
48 bit color
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8 bit grayscale
24 bit color
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8 bit grayscale
24 bit color
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Spatial Resolution
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600 ppi
300 – 400 ppi for larger maps
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150 – 200 ppi
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144 ppi
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Spatial Dimensions
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6000 – 8000 pixels across the long dimension
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1078 pixels across the long dimension
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150 – 200 pixels across the long dimension
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Film
For duplicates (negatives, slides, transparencies), match the original size. However, if original size is not known, the following recommendations are supplied: For a copy negative or transparency, scan at a resolution to achieve 4000 pixels across the long dimension. For duplicates, follow the scanning recommendations for the size that matches the actual physical dimensions of the duplicate.
Master scans of camera originals may be captured and saved in RGB, particularly those negatives that contain color information as a result of staining, degradation, or intentional color casts. Derivative files could later be reduced to grayscale in the scanning software or during post-processing editing.
Film
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Master
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Access
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Thumbnail
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File Format
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TIFF
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JPEG
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JPEG
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Bit Depth
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16 bit grayscale
48 bit color
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8 bit grayscale
24 bit color
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8 bit grayscale
24 bit color
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Spatial Resolution
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Resolution to be calculated from actual image format and/or dimensions - approx. 2800 ppi for 35mm originals, ranging to approx. 600 ppi for 8”x10” originals
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150-200 ppi
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144 ppi
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Spatial Dimensions
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4000 – 8000 pixels across long dimension of image area, depending on size of original and excluding mounts and borders
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600 pixels across the long dimension
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150 – 200 pixels across the long dimension
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Sound Recordings:
Sound Recordings
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Master
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Access
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Web streaming
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File Format
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Broadcast WAVE (BWF)
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Broadcast WAVE (BWF)
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MP3 (MPEG-2 Audio Layer III)
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Encoding
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Uncompressed Pulse-code modulation (PCM)
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Uncompressed Pulse-code modulation (PCM)
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Sampling Frequency
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96 or 48 kHz, depending upon characteristics of source item
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44.1 kHz
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128kbps (bitrate)
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Configuration
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Monophonic or stereo, depending upon characteristics of source item
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Two channel (dual mono or stereo), according to Red Book CD standards
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Enhancements
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Minimal cleanup (some removal of unrecorded segments, hisses, hums, artificial tones, and clicks as needed; compression and gain adjustments as needed)
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