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Proceedings Paper

Analysis of sharpness increase by image noise
Author(s): Takehito Kurihara; Naokazu Aoki; Hiroyuki Kobayashi
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Paper Abstract

Motivated by the reported increase in sharpness by image noise, we investigated how noise affects sharpness perception. We first used natural images of tree bark with different amounts of noise to see whether noise enhances sharpness. Although the result showed sharpness decreased as noise amount increased, some observers seemed to perceive more sharpness with increasing noise, while the others did not. We next used 1D and 2D uni-frequency patterns as stimuli in an attempt to reduce such variability in the judgment. The result showed, for higher frequency stimuli, sharpness decreased as the noise amount increased, while sharpness of the lower frequency stimuli increased at a certain noise level. From this result, we thought image noise might reduce sharpness at edges, but be able to improve sharpness of lower frequency component or texture in image. To prove this prediction, we experimented again with the natural image used in the first experiment. Stimuli were made by applying noise separately to edge or to texture part of the image. The result showed noise, when added to edge region, only decreased sharpness, whereas when added to texture, could improve sharpness. We think it is the interaction between noise and texture that sharpens image.

Paper Details

Date Published: 10 February 2009
PDF: 9 pages
Proc. SPIE 7240, Human Vision and Electronic Imaging XIV, 724014 (10 February 2009); doi: 10.1117/12.806078
Show Author Affiliations
Takehito Kurihara, Chiba Univ. (Japan)
Naokazu Aoki, Chiba Univ. (Japan)
Hiroyuki Kobayashi, Chiba Univ. (Japan)


Published in SPIE Proceedings Vol. 7240:
Human Vision and Electronic Imaging XIV
Bernice E. Rogowitz; Thrasyvoulos N. Pappas, Editor(s)

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