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Guidelines: Content Categories and Subcategories Objectives:
Reformatting Historical Printed Matter, Documents and Manuscripts,
and Pictorial Materials — Content Categories and Subcategories Table
Still Image Working Group

Back to Content Categories and Subcategories table

Category AR

Special-purpose images (aerial, medical, and scientific images, architectural and engineering line drawings and blueprints). Viewed by reflected light.

Subcategory AR.5

Architectural and engineering line drawings, diagrams, and blueprints. Curator or end users determine that bitonal reproduction is acceptable for items in this sub-category.

Use Cases: Master Images and Image Sets

  • Digitizing organization uses archival or production master image(s) to produce derivative images for the use cases listed under the tab to the right.
  • Digitizing organization uses the master (or migrated copies) to create a virtual replica or a physical replica of the original item in the event of its loss, deterioration, or de-accessioning.
  • Digitizing organization (or successor/receiving agency with an archiving mission) sustains the master (or migrated copies) for the long-term without loss of essential features.
  • Digitizing organization uses masters for disaster recovery in the event of impairment of digital asset management systems.

Quality Notes

  • Image-quality characteristics of the archival or production master image(s) must be sufficient to support the production of the various image types listed under the Derivative Images tab. Dependencies include appropriate image specifications and a production activity that applies appropriate process controls, e.g., the use of targets to monitor output, a quality assurance process that includes the use of color profiles, calibrated monitors and viewing environments, and various automated tools.
  • For future exploration: When should master images be in an original-referred image state?
  • Image-quality characteristics as above, plus completeness of coverage (in some cases capture of paper sheet "beyond the edge") must be sufficient to permit the use of the master (or migrated copies) to create a physical replica of the original item in the event of loss or deterioration. That is, the master will fill the niche formerly filled by copy negatives and copy transparencies.
  • Image-quality characteristics plus selection of sustainable digital-content formats must be sufficient to permit sustaining or migrating the master over the long-term without loss of essential features.
  • Disaster recovery in the event of the impairment of digital asset management systems depends upon the availability of metadata in standardized formats, including descriptive, administrative, and structural metadata, some or all of which may be embedded in individual images.


Bitonal master images may be recommended for some or all items in this subcategory. Examples include the architectural drawings found in in the Library of Congress HABS-HAER collection; for a sample of an 8.5x11-inch line drawing see http://memory.loc.gov/pnp/habshaer/wy/wy0000/wy0034/sheet/00002r.tif; for an 18x24-inch version of the same drawing, see http://memory.loc.gov/pnp/habshaer/wy/wy0000/wy0034/sheet/00002a.tif. (Complete item here: http://hdl.loc.gov/loc.pnp/hhh.wy0034.) Bitonal images do not provide good documentation of the physical condition of an original item, if an organization requires condition documentation of a line drawing, they may wish to produce tonal images similar to those in the AR3 subcategory.

Use Cases: Derivative Images and Image Sets

  • Patron views inline image in user interface.
  • Patron makes a hard copy of one or more images for personal use.
  • Patron is confident that the content received is an accurate and/or authentic reproduction of the original item.
  • Patron (or content delivery system) receives information on rights and restrictions (delivery system may act on that information, if appropriate).
  • Patron downloads one or more of the derivative images and, later, uses embedded metadata to identify the content and to determined technical and provenance information about the image.
  • Analyst studies fine details in the image.
  • Digitizing organization may run a process that yields descriptions of "low level features" (colors, shapes, etc.). These descriptions may then be indexed in a special application, permitting patrons to search for and/or analyze images according to color, shape, etc.
  • Publisher uses image to illustrate a high quality book.
  • Exhibit designer uses image for display "mural."
  • Broadcaster uses image in high-definition television program, possibly with a Ken Burns effect.

Quality Notes

    Inline image in user interface:

  • Pictorial content is reasonably clear. Zoom in may be required. If the master is bitonal, this viewing image will be most successful is converted to grayscale and reduced in size for display.
  • Hard copy output:

  • Equivalent to good quality photocopy. If the master is bitonal, this output image could be a rescaled bitonal ("typing paper size") or on that has been converted to grayscale.
  • Patron confidence in accuracy and/or authenticity:

  • Depends upon provenance metadata (attribute of the copy) and trustworthiness of the provider (attribute of the institution).
  • Example of, say, image details for study:

  • Researcher able to read fine print.
  • Image used for book illustration, large poster or exhibition mural:

  • "Studio quality," permitting an accurate reproduction of the lines of the original. Good enough to make printing plate(s) for line art.
    Note: A bitonal image generally offers the best reproduction at "actual size." The production of smaller or larger printing plates or hard copy will often require special processing that includes blurring, grayscaling, resizing, sharpening, and reducing to bitonal. Will it be an acceptable practice for the digitizing organization to leave these processes to the end user, and simply hand off an image "ready to process?"
  • Image for use in high-definition television program.

  • "Studio quality," permitting an accurate reproduction of the shapes and tones of the original. Good enough to fill high-definition screen and zoom in using a Ken Burns effect.

Note: Derivative images will generally be in an output-referred image state.

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Working Groups

Still Image Working Group
This group is involved in a cooperative effort to develop common digitization guidelines for still image materials.

Audio-Visual Working Group
The goal for this working group is to identify, establish, and disseminate information about standards and practices for the digital reformatting of audio-visual materials by federal agencies.

Last Updated: 11/07/2016