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Proceedings Paper

Digital image quality measurements by objective and subjective methods from series of parametrically degraded images
Author(s): Aura Tachó; Carles Mitjà; Bea Martínez; Jaume Escofet; Miquel Ralló
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Paper Abstract

Many digital image applications like digitization of cultural heritage for preservation purposes operate with compressed files in one or more image observing steps. For this kind of applications JPEG compression is one of the most widely used. Compression level, final file size and quality loss are parameters that must be managed optimally. Although this loss can be monitored by means of objective image quality measurements, the real challenge is to know how it can be related with the perceived image quality by observers. A pictorial image has been degraded by two different procedures. The first, applying different levels of low pass filtering by convolving the image with progressively broad Gauss kernels. The second, saving the original file to a series of JPEG compression levels. In both cases, the objective image quality measurement is done by analysis of the image power spectrum. In order to obtain a measure of the perceived image quality, both series of degraded images are displayed on a computer screen organized in random pairs. The observers are compelled to choose the best image of each pair. Finally, a ranking is established applying Thurstone scaling method. Results obtained by both measurements are compared between them and with other objective measurement method as the Slanted Edge Test.

Paper Details

Date Published: 18 November 2013
PDF: 8 pages
Proc. SPIE 8785, 8th Iberoamerican Optics Meeting and 11th Latin American Meeting on Optics, Lasers, and Applications, 87858V (18 November 2013); doi: 10.1117/12.2027001
Show Author Affiliations
Aura Tachó, Univ. Politècnica de Catalunya (Spain)
Carles Mitjà, Univ. Politècnica de Catalunya (Spain)
Bea Martínez, Univ. Politècnica de Catalunya (Spain)
Jaume Escofet, Univ. Politècnica de Catalunya (Spain)
Miquel Ralló, Univ. Politècnica de Catalunya (Spain)

Published in SPIE Proceedings Vol. 8785:
8th Iberoamerican Optics Meeting and 11th Latin American Meeting on Optics, Lasers, and Applications
Manuel Filipe P. C. Martins Costa, Editor(s)

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