Priberam Machine Learning Lunch Seminars

Priberam Machine Learning Lunch Seminar
Speaker: Mariana Almeida (IT)
Venue: IST Alameda, Sala PA2 (Edifício de Pós-Graduação)
Date: Wednesday, February 2nd, 2011
Time: 13:00
Lunch will be provided

Title: "Blind Separation and Blind Deblurring of Natural Images"

Abstract:

The thesis addresses two important nonlinear inverse problems in image
processing: the separation
of show-through and the bleed-trough mixtures and the blind deblurring
of images. New
solutions to cope with their high levels of indetermination are proposed.
Two separation methods are developed for the first problem. In a first
approach, the indeterminacy
of nonlinear Independent Component Analysis (ICA) is reduced through the
use of a
physical model with only four parameters. Based on other properties, a
wavelet-based method
is also developed. This non-iterative approach performs space-variant
non pixel-wise separation.
Both techniques reach separation results competitive with those of other
methods.
Regarding blind deblurring, the technique that is developed does not
impose strong restrictions
on the blurring filter, overcoming the ill-posedness of Blind Image
Deconvolution (BID) by
initially considering the main image edges and, progressively, handling
fainter and smaller ones.
The BID technique is extended for deblurring shift-variant degradations
in which the blurred
image consists of two layers that were subjected to different
degradations. The approach is
successfully tested on several images, with a variety of synthetic and
real-life blurs, both in
shift-invariant and two-layer problems. The deblurring results are
visually and quantitatively
better than those obtained with other state-of-the-art methods.

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Bio: Mariana Almeida graduated in Electrical Engineering by the
"Instituto Superior Técnico" (IST, the Engineering School of the
Technical University of Lisbon), Lisbon, Portugal, in 2005. She also
received the PhD degree in the Electrical Engineering Department of IST,
in 2010. Her PhD studies were developed in the field of blind image
separation and deconvolution, under the supervision of Prof. Luís B.
Almeida, at IT - Instituto de Telecomunicacões, Lisbon, Portugal. She is
currently a post-doc. student of Prof. Mário Figueiredo and an invited
Assintant Professor at "Instituto Superior das Ciências do Trabalho e da
Empresa" (ISCTE - Lisbon University Institute), Lisbon, Portugal.