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Proceedings Paper

ISO 20462: a psychophysical image quality measurement standard
Author(s): Brian W. Keelan; Hitoshi Urabe
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Paper Abstract

ISO 20462, a three-part standard entitled “Psychophysical experimental methods to estimate image quality,” is being developed by WG18 (Electronic Still Picture Imaging) of TC42 (Photography). As of late 2003, all three parts were in the Draft International Standard (DIS) ballot stage, with publication likely during 2004. This standard describes two novel perceptual methods, the triplet comparison technique and the quality ruler, that yield results calibrated in just noticeable differences (JNDs). Part 1, “Overview of psychophysical elements,” discusses specifications regarding observers, test stimuli, instructions, viewing conditions, data analysis, and reporting of results. Part 2, “Triplet comparison method,” describes a technique involving simultaneous five-point scaling of sets of three stimuli at a time, arranged so that all possible pairs of stimuli are compared exactly once. Part 3, “Quality ruler method,” describes a real-time technique optimized for obtaining assessments over a wider range of image quality. A single ruler is a series of ordered reference stimuli depicting a common scene but differing in a single perceptual attribute. Methods for generating quality ruler stimuli of known JND separation through modulation transfer function (MTF) variation are provided. Part 3 also defines a unique absolute Standard Quality Scale (SQS) of quality with one unit equal to one JND. Standard Reference Stimuli (SRS) prints calibrated against this new scale will be made available through the International Imaging Industry Association.

Paper Details

Date Published: 18 December 2003
PDF: 9 pages
Proc. SPIE 5294, Image Quality and System Performance, (18 December 2003); doi: 10.1117/12.532064
Show Author Affiliations
Brian W. Keelan, Eastman Kodak Co. (United States)
Hitoshi Urabe, Fuji Photo Film Co., Ltd. (Japan)

Published in SPIE Proceedings Vol. 5294:
Image Quality and System Performance
Yoichi Miyake; D. Rene Rasmussen, Editor(s)

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