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Proceedings Paper

Subjective quality factor revisited: a unification of objective sharpness measures
Author(s): Bror O. Hultgren
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Paper Abstract

A number of observer based objective measures of image sharpness have been proposed: Higgins, Granger, Cohen & Carison and Barten. Many of these measures, seemingly different in concept, are highly correlated with the psychovisual perception of sharpness. We re-examine the basis for these sharpness measures, and will show that: The signal power spectra of a number of real scenes exhibit a 1/u2 dependence. The corresponding amplitude spectra can be interpreted as the frequency disiribution of spatial frequency content in average scenes. The relationship of these results to simple models of image structure will be discussed. The log spatial integration used in all the measures is equivalent to performing a linear spatial frequency integration with a weighting function (1/u) given by the frequency of occurrence of information in real scenes. While the forms of the visual MTF are substantially different, the measures belong to a class of generalized log frequency sharpness measures that, for equivalent viewing conditions, provide equivalent objective measures of sharpness. The linear dependence of subjective sharpness with the generalized SQF makes this class of sharpness measures a useful tool for product development in both the photographic and display industries.

Paper Details

Date Published: 1 October 1990
PDF: 11 pages
Proc. SPIE 1249, Human Vision and Electronic Imaging: Models, Methods, and Applications, (1 October 1990); doi: 10.1117/12.19688
Show Author Affiliations
Bror O. Hultgren, Polaroid Corp. (United States)

Published in SPIE Proceedings Vol. 1249:
Human Vision and Electronic Imaging: Models, Methods, and Applications
Bernice E. Rogowitz; Jan P. Allebach, Editor(s)

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