Special Section on Image Quality

Slider-adjusted softcopy ruler for calibrated image quality assessment

[+] Author Affiliations
Elaine W. Jin

Aptina, LLC, 3080 North First Street, San Jose, California 95134

Brian W. Keelan

Aptina, LLC, 3080 North First Street, San Jose, California 95134

J. Electron. Imaging. 19(1), 011009 (January 08, 2010). doi:10.1117/1.3271133
History: Received April 30, 2009; Revised August 11, 2009; Accepted August 13, 2009; Published January 08, 2010
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ISO 20462 part 3 standardized the hardcopy quality ruler and a softcopy quality ruler based on a binary sort approach involving paired comparisons. The new softcopy ruler method described here utilizes a slider bar to match the quality of the ruler to that of the test image, which is found to substantially reduce the time required per assessment (30to15.5s), with only a modest loss of precision (standard deviations of 2.5 to 2.9 just noticeable differences). In combination, these metrics implied a 20% improvement in the standard error of the mean achievable in a fixed amount of judging time. Ruler images calibrated against the standard quality scale of ISO 20462 are generated for 21 scenes, at 31 quality levels each, achieved through variation of sharpness, while other attributes are held near their preferred positions. The images are bundled with documentation and a MATLAB source code for a graphical user interface that administers softcopy ruler experiments, and these materials are donated to the International Imaging Industry Association for distribution. In conjunction with a specified large flat panel display, these materials should enable users to conduct softcopy quality ruler experiments with minimum effort, and should reduce the barriers to performing calibrated psychophysical measurements.

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© 2010 SPIE and IS&T

Citation

Elaine W. Jin and Brian W. Keelan
"Slider-adjusted softcopy ruler for calibrated image quality assessment", J. Electron. Imaging. 19(1), 011009 (January 08, 2010). ; http://dx.doi.org/10.1117/1.3271133


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