ERIC Number: ED382205
Record Type: Non-Journal
Publication Date: 1995-Apr
Reference Count: N/A
Digital Resolution Requirements for Replacing Text-Based Material: Methods for Benchmarking Image Quality. Tutorial.
Kenney, Anne R.; Chapman, Stephen
This tutorial provides a means to estimate resolution requirements for the use of digital imaging technology in converting text-based material. It is suggested that benchmarks for resolution can be calculated by evaluating the physical attributes of source documents and by applying Quality Index formulas that have been derived from those established for preservation microfilming. The formulas are based on three variables: the height of the smallest significant character, the desired quality to be obtained in the reformatted version, and the resolution of the recording device. For the past several years, the Cornell University Department of Preservation and Conservation (New York) has experimented using the Digital Quality Index formula to predict resolution requirements for a wide range of documents using a number of scanning devices. The results of these and other experiments confirm the utility of the Digital Quality Index formula for bitonal (black and white) scanning, but a slight modification to the formula is recommended in cases where grayscale scanning is employed. It is cautioned that the use of these formulas are for benchmarking purposes only. Assessment methods for scanner performance are discussed, and a continuous quality assurance program is recommended. Sections include: "Where to Begin"; "How To Determine Digital Image Quality"; "Scanning Methodologies and Compression Techniques"; "Bitonal Scanning"; "Grayscale Scanning"; "Verifying the Predicted Quality Index"; "Visual Inspection"; "Suggested Guidelines" and "Summary of Recommendations." Seven figures and three tables illustrate the process and data. (Contains 20 references.) (MAS)
Commission on Preservation and Access, 1400 16th Street, N.W., Suite 740, Washington, DC 20036-2217 ($10 prepaid).
Publication Type: Reports - Descriptive
Education Level: N/A
Authoring Institution: Commission on Preservation and Access, Washington, DC.