
Proceedings Paper
Filtering and luminance correction for aged photographsFormat | Member Price | Non-Member Price |
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Paper Abstract
We virtually restore faded black and white photographic prints by the method of decomposing the image into
a smooth component that contains edges and smoothed homogeneous regions, and a rough component that may
include grain noise but also fine detail. The decomposition into smooth and rough components is achieved using
a rational filter. Two approaches are considered; in one, the smooth component is histogram-stretched and then
gamma corrected before being added back to a homomorphically filtered version of the rough component; in the
other the image is initially gamma corrected and shifted towards white. Each approach presents improvements
with respect to the previously separately explored techniques of gamma correction alone, and the stretching
of the smooth component together with the homomorphical filtering of the rough component, alone. After
characterizing the image with the help of the scatter plot of a 2D local statistic of the type (local intensity, local
contrast), namely (local average, local standard deviation), the effects of gamma correction are studied as the
effects on the scatter plot, on the assumption that the quality of the image is related to the distribution of data
on the scatter plot. Also, the correlation coefficient between the local average and the local deviation on the one
hand, and the global average of the image play important descriptor roles.
Paper Details
Date Published: 1 March 2008
PDF: 11 pages
Proc. SPIE 6812, Image Processing: Algorithms and Systems VI, 681202 (1 March 2008); doi: 10.1117/12.764826
Published in SPIE Proceedings Vol. 6812:
Image Processing: Algorithms and Systems VI
Jaakko T. Astola; Karen O. Egiazarian; Edward R. Dougherty, Editor(s)
PDF: 11 pages
Proc. SPIE 6812, Image Processing: Algorithms and Systems VI, 681202 (1 March 2008); doi: 10.1117/12.764826
Show Author Affiliations
Alfredo Restrepo, Univ. of Trieste (Italy)
Giovanni Ramponi, Univ. of Trieste (Italy)
Published in SPIE Proceedings Vol. 6812:
Image Processing: Algorithms and Systems VI
Jaakko T. Astola; Karen O. Egiazarian; Edward R. Dougherty, Editor(s)
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