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Center for Digital Research in the Humanities

Scanning and Digital Imaging Benchmarks

  1. Purpose of Reproduction
    1. To provide greater access to original objects
    2. To assist in the preservation of original objects
    3. To enhance and develop content-rich resources
    4. To assist in collection development
  2. Criteria for Selecting a Capture Technique
    1. The following factors may be considered when evaluating the nature of the item to be digitally imaged:
      1. Is the item a single leaf, or bound?
      2. Is the item a slide, microform, or transparency?
      3. If bound, how tight is the binding?
      4. Will the item fit on a scanner?
      5. Will scanning a bound item cause damage to the paper or to the binding?
      6. Will exposure to light damage the item?
  3. Judging Condition and Value of Original
    1. The following factors may be considered when choosing an object for digital reproduction:
      1. What intellectual value does the object or artifact have?
      2. What intrinsic, or artifactual, value does the object have?
      3. How unique or rare is the object?
      4. How importance is the object for research and use?
      5. How does the artifact relate to a specific topic or area of study?
      6. What are the physical characteristics of the object, including any unique or unusual details, shape, color, etc?
      7. What aspects of the original object should be retained or discarded in the digital reproduction?
    2. The following factors may be considered in the creation of a digital reproduction:
      1. Will the digital reproduction have value over the long-term?
      2. Will the digital reproduction add to content resources?
      3. Who is the intended audience for the digital reproductions or the digital project?
      4. What are the legal restrictions on creating a digital reproduction of an object?
      5. Are there specific copyright restrictions?
      6. What are the costs involved in creating a digital reproduction and maintaining the digital reproduction long term?
  4. Handling Originals
    1. Use gloves when handling any photographs or negatives.
    2. For negatives, the emulsion side should be placed on the bed of the scanner.
    3. Occasionally, flat items may be difficult to remove from the scanner bed. A small suction cup can assist in lifting the item enough to capture it with fingers. Suction cups should not be used on the emulsion side of a negative or image.
    4. Handle manuscripts, bound items and books with care, particularly fragile books that have damage to the spine, covers, or text block. Gloves may be used to avoid contact with disintegrating leather bindings.
    5. Gloves may also need to be used for artifacts.
  5. Benchmarks
    1. Master images are meant to capture the original object and should mirror or duplicate it as exactly as possible. Derivatives made from the master scan may include changes or corrections in the appearance of the object for presentation purposes.
    2. Always use the color bar when scanning color photographs. It is not necessary to use the color bar when scanning negatives or transparencies or when scanning an image in grayscale.
    3. The color bar can be placed anywhere around the image. Capture enough of the color bar to distinguish the colors. The entire bar does not need to be included unless the measurements of an image or object need to be captured (e.g. for photographic captures).
    4. The color bar should remain several millimeters away from the artifact, to facilitate easy removal of the bar in derivative images.
    5. The color bar should be used when scanning objects of "high artifactual value" or importance. In these instances, best judgment may be used when considering the use of a color bar. Please note that the color bar does not need to be used with the Zeutschel overhead book scanner.
    6. All images are scanned with RGB color. The exception to this includes black and white photographs that are "true" black and white in color, not those with a sepia or brown tone. These items may be scanned in grayscale.
    7. All scans of transparent items should be completed in "transparency" mode in the scanning software.
    8. The benchmarks used for creating digital scans and images are meant to comply with or exceed the recommendations of the "Digital Library Federation Benchmark for Faithful Digital Reproductions of Monographs and Serials."
    9. Scanning benchmarks should adapt to the original item or type of media that is being scanned.
    10. Recommendations for different types of objects are noted in the table below:

    Type of Object

    DLFB Minimum

    UNL Recommendations

    Color bar

    Specifications

    Manuscript text

    600 dpi, 1-bit or bitonal

    Kodak
    color

    600 dpi, 24-bit
    Color

    Printed text

    600 dpi, 1-bit or bitonal

    Kodak
    color

    300 dpi, 24-bit
    Color

    Printed text with graphics

    300 dpi, 8-bit grayscale

    Kodak
    color

    600 dpi, 24-bit
    Color

    Black White Photograph

    300 dpi, 8-bit grayscale

    Kodak
    Color or
    grayscale

    600 dpi, 24-bit
    color or grayscale

    Color Photograph

    300 dpi, 24-bit color

    Kodak
    color

    600 dpi, 24-bit
    Color

    Black White Photo Negative/Transparency

    Equiv. 300 dpi, 8-bit grayscale

    N/A

    Equiv.
    1200 dpi, grayscale

    Color Photo Negative/Transparency

    Equiv. 300 dpi, 24-bit color

    N/A

    Equiv.
    1200 dpi, 24-bit color

    Microforms

    Equiv. 300 dpi, 8-bit grayscale

    N/A

    Equiv. 600 dpi, 24-bit
    grayscale

    Maps

    300 dpi, 24-bit color

    Kodak
    Color

    600 dpi, 24-bit
    Color

  6. Metadata
    1. The following list describes the recommended metadata for digital images. Please note that not all fields may be used for each item. Please see Appendix A for field definitions.
      1. Number
      2. LC Call Number
      3. Dewey Call Number
      4. RGNumber/MSNumber
      5. Location
      6. Containers
      7. Collection Name
      8. Original Item Number
      9. Optional Number
      10. Creator
      11. Keyword(s)/Subject(s)
      12. Keyword(s) Location
      13. Description
      14. Date/Date Range
      15. Copyright Ownership
      16. Physical Ownership
      17. Original Size
      18. Original Photo Type
      19. Original Manuscript Type
      20. Original Multimedia Type
      21. Scan File Name
      22. Master Scan
      23. Thumbnail
      24. Grayscale or RGB
      25. Resolution
      26. File Format
      27. Scanning Notes
      28. Capture Mechanism
      29. Operator
      30. Scanner/Colorbar
      31. Scan Date
      32. Refreshment Date
      33. Refreshment Cycle
      34. Master File Location
      35. Print File Location
      36. Manipulation Notes
      37. Redo
  7. File Name Protocol
    1. File names of digital images may be developed from the title of a project, the title of a collection or a collection number, or from the title of the object itself. The file names are based on relevance to a project or to the object. Metadata for the digital images or files will capture pertinent data such as creator, dates, etc.
    2. Recommendations include a two to three character prefix that designates a clear association with a specific project.
    3. All file identifiers for files stored on CD-ROMs should be compliant with ISO-9660:1988, and its relevant extensions mentioned below.
      1. Examples that meet the standards listed:
        1. Willa Cather Archive: cat.0001.001.tif
        2. Western Waters, The Platter River Basin in Nebraska: ww.00019.001.tif
    4. File identifiers (often referred to as filenames) can be up to 30 characters in length, including: (1) the file name (before the file extension), (2) the dot separator(s), and (3) the file extension.
      1. Example: cc.0123456789.tif (17 characters in length)
    5. Length of file path, including file identifier, cannot exceed 255 characters.
      1. Example:images/westernwaters/tiffs/uncorrected/ww.0123456789.tif (56 characters in length)
    6. Alphabetical characters in file identifiers should conform to the Rock Ridge Interchange Protocol (RRIP). RRIP extends ISO-9660:1988, while remaining completely compliant with it.
      1. File names may include the following characters: A-Z, a-z,".", "_", "-" (period, underscore, and hyphen)
      2. Example: "Pic.0001.c-2_small.tif" would be a valid file name. "Picture 3 of 40.tif" is not a valid filename because it contains illegal spaces.
    7. Numerical characters are allowed in file identifiers.
      1. Example:0-9
  8. Storage
    1. Digital images are stored in the TIFF file format. Derivatives may include the following: JPEG, JPEG2000, GIF, PNG, and PDF.
    2. Digital image files stored on CD-ROMs should include master TIFF files and may also include derivatives created in support of a project.
    3. Information on content of CD-ROMs should be maintained for easy access to original master images stored on them. Currently in Archives and Special Collections this is kept on the Digital Imaging Database.
    4. In addition to digital images, the metadata on each image file should be retrieved from the Digital Imaging Database, saved in an XML or a delimited text format and burned onto the CD-ROMs as well. The database software allows export of specific records. This ensures that metadata for images exist on the storage media.
    5. CD-ROMs should be tested to ensure that the files can be retrieved.
  9. Caring for CD-ROMs
    1. Store vertically.
    2. Do not touch reflective surface of disc.
    3. Do not bend.
    4. Store in archival sleeves, or jewel cases.
    5. Temperature conditions should remain between 41 and 72 degrees Fahrenheit.
    6. While the long-term effect of ambient room lighting is unknown, generally it is recommended that CD-ROMs be stored in a box or other enclosure.
    7. Do not write on the CD-ROMS, unless you use a CD-safe marker, and even then only mark on the clear plastic hub where there is no data.
    8. Do not apply adhesive labels.
    9. Avoid cleaning discs, unless the disc is unreadable or obviously very dirty. Wipe from the center of the disk outward, NOT in a circular spiral around the disc.
  10. Recommended Guidelines and Resources
    1. Digital Library Federation: Benchmark for Faithful Digital Reproductions of Monographs and Serials, http://www.diglib.org/standards/bmarkfin.htm
    2. The NINCH Guide to Good Practice in the Digital Representation and Management of Cultural Heritage Materials, http://www.nyu.edu/its/humanities/ninchguide/VI/
    3. Moving Theory Into Practice Digital Imaging Tutorial, http://www.library.cornell.edu/preservation/tutorial/index.html
    4. Columbia University Libraries Selection Criteria For Digital Imaging, http://www.columbia.edu/cu/libraries/digital/criteria.html
    5. "Image Scanning: A Basic Helpsheet" Electronic Text Center, University of Virginia, http://etext.lib.virginia.edu/services/helpsheets/scan/scanimage.html
    6. "Digital Imaging for Photographic Collections: Foundations for Technical Standards," Franziska Frey, James M. Reilly, Image Permanence Institute, Rochester Institute of Technology, http://www.rit.edu/~661www1/sub_pages/digibook.pdf
    7. "Digital Conversion Methodologies," Jill Koelling, Nebraska State Historical Society, http://www.nebraskahistory.org/lib-arch/research/photos/digital/methods.htm

Appendix A METADATA DEFINITIONS (Archives 2003)

  1. Number: The number in this field is automatically assigned to a record in a database.
  2. LC Call Number: If an image or page has been scanned from an item that is cataloged with a LC call number, provide the call number. Be sure to record the page number as a part of this field.
  3. Dewey Call Number: If an image or page has been scanned from an item that is cataloged with a Dewey number, provide the call number. Be sure to record the page number as a part of this field.
  4. RGNumber/MSNumber: This field contains the record group number or the manuscript number assigned to a collection from any archival repository. For example, the Library of Congress uses "record group" to designate certain collections. Please use the letters RG prior to a record group number and MS prior to a manuscript number.
  5. Location: This provides information on the location of an item within a collection or within an archival repository. For example, the location could be recorded as "Library of Congress." For security reasons, this is not meant to provide information on the location of an item on shelves, etc.
  6. Containers: If it is available, record the box number and the folder number. The words "box" and "folder" can be abbreviated. For example, B1, F4, etc.
  7. Collection Name: This field contains the name of the collection in which the material is located. It can be abbreviated to the last name and first name from the collection title. For example "Slote, Bernice" or "Feinberg, Charles." If there is more than one collection with the same name, an initial should be included. This information will help interpret the file name of each scan.
  8. Original Item Number: The number of the original item is entered into this field. Not all items have been assigned a number.
  9. Optional Number: This number may be used to record additional numbers on an artifact or as needed for a project.
  10. Creator: This field contains information on person who created the original item, such as a photographer, an author, or a photography studio. For a professional studio the location should be included if it is available.
  11. Keyword(s)/Subject(s): Keywords or subjects are brief one word or two word descriptions of the image, each separated by a semi-colon. Include names of individuals that are represented if they are identified and please use their full name. The name or subject should reflect the Library of Congress entry in the online catalog. The description should be based on information provided or those objects or scenes identified in the first few seconds of looking at the image. This field is a searchable field and will be the field used to locate an image by keyword or subject. Note information on "who," "what," "why" and "how." Information on "when" and "where" are entered into separate fields.
  12. Keyword(s)/Location: If a place or location is identified include it. The place name can be separated by commas, similar to an address. For example: Thomas Co., NE or Frederick Co., Virginia. This provides the "where" information for a photograph.
  13. Description: This field contains description of the item that provides additional "who," "what," and "where," "etc" information about the image. It may be information that is known, such as "Willa Cather in France camping, next to a tent with a white dress," or it may be very general information. This is a memo field so as much information as may be needed can be entered and complete sentences or longer phrases can be used. This is not a searchable field.

    Date/DateRange: Enter a date for an artifact or photograph in this field based on the UNL EAD, ISO 8601standard noted below.
    Year, Month, Day = YYYY-MM-DD
    Single Year= YYYY
    Year Range= YYYY-YYYY
    Year, Month Range= YYYY-MM/YYYY-MM
    Year, Month, Day Range= YYYY-MM-DD/YYYY-MM-DD
    Approximate Year= YYYY-YYYY (within a five year span)
    Approximate Decade = YYYY-YYYY (with a ten year, one decade span)
    Undated=YYYY-YYYY (For an item from a collection, this would be the date range for the entire collection)

  14. Copyright Ownership: Record any information on copyright of the photograph, taken from the object or from information about the collection. Information may be provided on the back of the image. Generally, the item is no longer under copyright if it is created before 1923. Copyright may have been granted to the UNL Libraries, another entity, or may still be held by the donor or creator of the collection. If the creator or donor still owns copyright, this information should be added to the field.
  15. Physical Ownership: The default option for this field is UNL Libraries. Information on other repositories or institutions may appear here.
  16. Original Size: This is the size of the original object as measured in centimeters.
  17. Original Photo Type: Select one of the options listed. Albumen Print; Ambrotype; Black/White Print; Cabinet Card; Carte de visite; Color Negative; Color Print; Copy Negative; Daguerreotype; Diacitate Negative; Ferrotype (Tintype); Gelatin Silver Postcard; Gelatin Silver Print; Glass Plate; Lantern Slide; Linen Postcard; Nitrate Negative; Photo Album Page; POP (Printing Out Paper) Print; Polyester Negative; Real Photo Postcard; Stereoview; Transparency; Wet Plate Negative
  18. Original Manuscript Type: Select one of the options listed. Additional options may be added as necessary: Account Book; Diary Page; Envelope; Field Notes; Journal; Letter; Manuscript; Newspaper Clipping; Postcard; Scrapbook, Book
  19. Original Multimedia Type: Select one of the options listed: Film Frame; Film Strip
  20. ScanFileName: This is the number assigned to the image based on the File Naming Protocol document. The number provided at the end should match to the automatically supplied number in the Digital Imaging Database.
  21. Master Scan: Yes/No, A master image has been made.
  22. Thumbnail: Yes/No, A thumbnail of the image has been created.
  23. Grayscale or RGB: Select either grayscale or RGB. As noted in the "Scanning Steps" document, all images are made in RGB, with the exception of black and white photographs that are "true " black and white in color.
  24. Resolution: Record the resolution used to create the file. At this time, our benchmarks require a resolution of 600 ppi.
  25. File Format: This field contains the file format of the scanned image. The default for this field should be a TIFF file.
  26. Capture Notes: Record any special settings in the software used for the capture mechanism. For example, capture levels in scanning software.
  27. Capture Mechanism: Place information regarding how the image was captures, by scanner, digital camera, overhead book scanner, etc. Record information on the type of capture mechanism used, such as the brand name of a scanner.
  28. Operator: The name of the individual who created the digital image.
  29. Colorbar: Record the type of color bar used for the image.
  30. Creation Date: Record the actual date when the electronic file was created.
  31. Refreshment Date: This contains information on the refreshment date of file. Enter the year, three or five years from the ScanDate, when the file will need to be migrated or refreshed. Three years is the earliest date, and five years the maximum of number of years before the files should be migrated to a new storage media.
  32. Refreshment Cycle: Record the number of times the file has been refreshed. Include information on, or the date, when the actual refreshment of the file took place.
  33. Master File Location: Record the number of the CD-Rom, or DVD, that contains the master images.
  34. Print File Location: If a print is made of the scanned image, provide information on the location of the print.
  35. Manipulation Notes: Record any information about manipulation of the image with software such as Photoshop. This includes any enhancements, etc. done to the image. Generally, there is no manipulation of a master image.
  36. Redo: Yes/NoSelect whether the image should be redone or not. This may be necessary if the benchmarks have not been met or if the image is not of good qualiy.
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