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

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 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 calibrated monitors and viewing environments, and various automated tools.
• For future exploration: When should master images be in an original-referred image state? For informational-only content items like these, when would lossy compressed masters be acceptable?
• In order to sustain or migrate the master over the long-term without loss of essential features, the following features are required: (1) image-quality characteristics as above, (2) structural metadata as above, and (3) the selection of sustainable digital-content formats.
• Disaster recovery in the event of the impairment of digital asset management systems depends upon the availability of metadata in standardized formats, including embedded image-level metadata and work-level descriptive, administrative, and structural metadata.
  

Comments

Note that the use cases for T.2 masters and derivative images are identical to those for T.4 masters and derivative images. At this writing, image specifications have not be defined for either of these subcategories, but the authors of this Web page foresee that :

• T.2 and T.4 master images (and image sets) are very likely to have the same specifications
• T.2 and T.4 derivative images (and image sets) may or may not have the same specifications
• The methods used to produce derivative images from the masters for subcategories T.2 and T.4 may differ.

Use Cases: Derivative Images and Image Sets

• Patron sees or reads 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.
• Digitizing organization runs OCR process to produce text. Patrons may read, search, or download this text for a variety of uses.
  

Quality Notes

Inline image in user interface:

•  Text is legible and graphic illustration content is reasonably clear. Zoom in may be required. In rare cases, legibility may depend upon contrast stretching.

Hard copy output for personal use:

• As good as a photocopy.

Patron confidence in accuracy and/or authenticity:

• Depends upon provenance metadata (attribute of the copy) and trustworthiness of the provider (attribute of the institution).

Images for OCR processing:

• Produce text at accuracy of 95 percent or higher.

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

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