1. Stephen Chapman and Anne R. Kenney, "Digital Conversion of Library Research Materials: A Case for Full Informational Capture," D-Lib Magazine (October 1996). [BACK]

2. Currently, scanning is the most cost-effective means to create digital files, and digital imaging is the only electronic format that can accurately render the information, page layout, and presentation of source documents, including text, graphics, and evidence of age and use. By producing digital images, you can create an authentic representation of the original at minimal cost and then derive the most useful version and format (e.g., marked-up text) for transmission and use. [BACK]

3. Michael Lesk, Image Formats for Preservation and Access: A Report of the Technology Assessment Advisory Committee to the Commission on Preservation and Access, Commission on Preservation and Access, Washington, DC, July 1990. [BACK]

4. See Charles S. Rhyne, Computer Images for Research, Teaching, and Publication in Art History and Related Disciplines, Commission on Preservation and Access, Washington, DC, January 1996, p. 4, in which he argues that "with each jump in [on-screen image] quality, new uses become possible." [BACK]

5. Interesting work is being conducted at Xerox PARC on image summarization. See Francine R. Chen and Dan S. Bloomberg, "Extraction of Thematically Relevant Text from Images," paper presented at the fifth annual Symposium on Document Analysis and Information Retrieval, Las Vegas, April 15-17, 1996. [BACK]

6. An interesting conclusion from a project on the use of art and architectural images at Cornell focused on image size guidelines to support a range of user activities. For browsing, the project staff found that images must be large enough for the user to identify the image, but small enough to allow numerous images to be viewed simultaneously-the physical size on the screen preferred by users was 1.25" to 2.25" square. For viewing images in their entirety, images were sized to fit within a 5.5" square; for studying, detailed views covering the entire screen were necessary; and for "authoring" presentations or other multimedia projects, users preferred images that fit in a half-inch square. See Noni Korf Vidal, Thomas Hickerson, and Geri Gay, "Developing Multimedia Collection and Access Tools, Appendix V. Guidelines for the Display of Images'' (report delivered to the Council on Library Resources, April 1996), 14-17. [BACK]

7. A number of leading experts advocate this approach, including Michael Ester of Luna Imaging, Inc. See, for example, Michael Ester, "Digital Images in the Context of Visual Collectons and Scholarship," Visual Resources 10 (1990): 11-24; and "Specifics of Imaging Practice," Archives and Museum Informatics: Hands-on Hypermedia and Interactivity in Museums, Selected Papers from the Third International Conference, San Diego, CA, October 9-13, 1995. [BACK]

8. Roger S. Bagnall, Digital Imaging of Papyri: A Report to the Commission on Preservation and Access, Commission on Preservation and Access, Washington, DC, September 1995; Janet Gertz, Oversize Color Images Project, 1994-1995 Final Report of Phase I, Commission on Preservation and Access, Washington, DC, August 1995; Picture Elements, Inc., Guidelines for Electronic Preservation of Visual Materials, Part I, Report to the Library of Congress, March 2, 1995. Michael Ester argues that an "archival image" of a photograph cannot be benchmarked through calculations but should be pegged to the "functional range of an institution's reproduction sources." See page 11 in Ester, Digital Image Collections: Issues and Practice, Commission on Preservation and Access, Washington, DC, December 1996. For a critique of this approach, see Chapman and Kenney, "Digital Conversion." [BACK]

9. Don Williams, "What Is an MTF and Why Should We Care?" RLG Diginews 2(1) (February 15, 1998), http://www.rlg.org/preserv/diginews. [BACK]

10. Anne R. Kenney and Stephen Chapman, "Film Scanning," Chapter 7 in Digital Imaging for Libraries and Archives, Cornell University Library, Ithaca, NY, 1996, p. 169. [BACK]

11. ANSI/AIIM MS 23 -1991, Practice for Operational Procedures/Inspection and Quality Control of First-Generaton, Silver Microfilm and Documents, Association for Information and Image Management; ANSI/AIIM TR26-1993, Resolution as It Relates to Photographic and Electronic Imaging, Association for Information and Image Management; and Kenney and Chapman, Tutorial: Digital Resolution Requirements for Replacing Text-Based Material: Methods for Benchmarking Image Quality, Commission on Preservation and Access, Washington, DC, April 1995. [BACK]

12. For a description of this verification process, see Anne R. Kenney, "Digital-toMicrofilm Conversion: An Interim Preservation Solution," Library Resources and Technical Services (October 1993): 380-401; (January 1994): 87-95. [BACK]

13. Anne R. Kenney and Oya Y. Rieger, Using Kodak Photo CD Technology for Preservation and Access, Cornell University Library, Ithaca, NY, 1998. [BACK]

14. A fuller explanation of the display benchmarking process is included in Anne R. Kenney and Stephen Chapman, Chapter 2 in Digital Imaging for Libraries and Archives, Cornell University Library, Ithaca, NY, 1996, pp. 76-86. [BACK]

15. Improvements in managing color digitally may be forthcoming from an international consortium of industry leaders working to develop an electronic prepress industry standard. Their "International Color Consortium Profile Format" is intended to represent color consistently across devices and platforms. [BACK]

16. See Peter van Minnen, "Imaging the Duke Papyri," (December 1995) http:// odyssey.lib.duke.edu/papyrus/texts /imaging.html, and Roger S. Bagnall, Digital Imaging of Papyri: A Report to the Commission on Preservation and Access, Commission on Preservation and Access, Washington, DC, September 1995. [BACK]

17. Rhyne, Computer Images, 5. [BACK]

18. The formula for calculating the maximum percentage of a digital image that can be displayed on-screen is as follows:

a. If both image dimensions < the corresponding pixel dimensions (pd) of the screen, 100% of the image will be displayed.

b. If both image dimensions > the corresponding pixel dimensions of the screen, % displayed = horiz. screen pd ³ vertical screen pd ³ 100 image's horiz. pd ³ image's vertical pd.

c. If one of the image's dimensions < the corresponding pixel dimension of the screen, % displayed = image's opposite pixel dimension ³ 100. [BACK]

19. The scaling formula for complete display of image on screen is as follows:

a. When digital image aspect ratio < screen aspect ratio, set image's horizontal pixel dimension to the screen's horizontal pixel dimension.

b. When digital image aspect ratio > screen aspect ratio, set image's vertical pixel dimension to the screen's vertical pixel dimension. [BACK]

20. This formula presumes that bitonal images are presented with a minimum level of gray (3 bits or greater) and that filters and optimized scaling routines are used to improve image presentation. [BACK]