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   -> Volume 6, Issue 8

Question: Edge detection in noisy images
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Author Message (Roger FJXRTOFT)

PostPosted: Sun Jul 20, 1997 2:27 pm    
Subject: Question: Edge detection in noisy images
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#24 Question: Edge detection in noisy images

Dear Wavelet Digest readers,

As a part of my thesis work, I try to evaluate the potential of
wavelet-based techniques for edge detection in noisy images, in
particular SAR images. Orthogonal wavelet transforms have been shown
to have excellent properties for image compression, but according to
several authors, shift-invariant (and thus redundant) transforms
should be used for image analysis problems such as edge detection. The
multiscale aspect is interesting in itself, but what exactly is the
contribution of wavelet theory in the case of edge detection based on
a shift-invariant transform? Does the use of wavelets have any
advantage compared to other multiscale approaches, such as the Canny
edge detector or spatially adaptive operators? Singularities are
characterized by their Lipschitz exponents, which can be estimated
from the evolution of the wavelet coefficients across the scales, as
described by Mallat et al. Has any robust, wavelet-based edge
detection algorithm been proposed, which explicitly states how the
results obtained on different resolution levels should be combined?
Thank you in advance!


Roger Fjortoft
Centre d'Etudes Spatiales de la Biosphere (CESBIO)
18 avenue Edouard Belin, bpi 2801, 31401 Toulouse cedex 4, France
Phone: (+33) 5 61 55 66 70
Fax: (+33) 5 61 55 85 00

[Answer: WD 11.6 Topic 5263]
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