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The optimal one-dimensional (1-D) window, an index-limited sequence with maximum energy concentration in a finite frequency interval, is related to a particular discrete prolate spheroidal sequence. This letter presents the N-dimensional (N-D) extension, i.e., the N-D window with limited support and maximum energy concentration in a general nonseparable N-D(More)
In financial market risk measurement, Value-at-Risk (VaR) techniques have proven to be a very useful and popular tool. Unfortunately, most VaR estimation models suffer from major drawbacks: the log-normal (Gaussian) modeling of the returns does not take into account the observed fat tail distribution and the non-stationarity of the financial instruments(More)
In the past we have proposed a pseudo-colorimetric imaging system for dermatological uses. The system exhibits moderate accuracy, but high precision or re-producibility. Acquired images are stored in the well-defined gamma-corrected sRGB color space. This color space has a known relationship to the perceptually uniform CIE L * a * b * color space, which(More)
— The common method neonatol-ogists use nowadays to determine White Matter Damage (leukomalacia) is by visual inspection of ultrasound images of the neonatal brain. A need for a (semi)-computerized way of delineating the affected regions, in order to make quantitative measurements as an aid to the subjective diagnosis , is felt. The use of active contours(More)
We study global optimization (GOP) in the framework of non-linear inverse problems with a unique solution. These problems are in general ill-posed. Evaluation of the objective function is often expensive, as it implies the solution of a non-trivial forward problem. The ill-posedness of these problems calls for regularization while the high evaluation cost(More)
The accurate quantification of single photon emission computed tomography (SPECT) and positron emission tomography (PET) data is limited by partial volume effects (PVE). This study compares two approaches to measure accurately the true tissue tracer activity within a tissue compartment, defined by anatomical side information. The first approach is based on(More)
In financial market risk measurement, Value-at-Risk (VaR) techniques have proven to be a very useful and popular tool. Unfortunately, most VaR estimation models suffer from major drawbacks: the lognormal (Gaussian) modeling of the returns does not take into account the observed fat tail distribution and the non-stationarity of the financial instruments(More)
Quantitative determination of local radioactivity concentration in positron emission tomography (PET) requires a good attenuation correction procedure to reconstruct the emission image. Using a similar Maximum Likelihood (ML) algorithm as for the reconstruction of the emission image, a method is proposed to reconstruct a transmission image, i.e. a map of(More)
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