Blood vessels overlying one another at distinct depths (and hence appearing to intersect) in the conjunctiva of the eye can be distinguished reliably from those that in fact do branch within the same depth, using only...
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Blood vessels overlying one another at distinct depths (and hence appearing to intersect) in the conjunctiva of the eye can be distinguished reliably from those that in fact do branch within the same depth, using only the information contained in a single photograph of the conjunctiva. That conclusion arises from extension of earlier work that qualitatively inferred relative depth of vessels. The current research was motivated by the need to quantify such inferences in terms of their sensitivities and robustness. Features extracted from an image are shown to be useful in that effort; their utility is verified with phantoms that mimic the behavior of the conjunctiva and the backing sclera. Because no special preparations are needed, the method works as well on archived images as on newly-acquired ones, and thus can be used in retrospective studies of images of the eye and other diffuse media.
Presents work on automatic inter-modality image registration based on the extraction of the most well-known image feature-edges. While many of the current techniques use the corresponding surface feature (skin surface...
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Presents work on automatic inter-modality image registration based on the extraction of the most well-known image feature-edges. While many of the current techniques use the corresponding surface feature (skin surface and brain surface in particular) for image registration, an edge feature can include ail of those surfaces as well as certain tissue structures. The edge feature may provide as well the simplicity and possibility for surface and contour information to be further constructed. In contrast to most of the modern surface registration algorithms which rely on either manual or automatic segmentation of the corresponding surface, the authors' 3-D edge registration algorithm requires no further segmentation for the registration of CT and MR brain images. The registration accuracy is evaluated through a fiducial "gold-standard" on 6 pairs of CT and MR (T1, T2, and PD) images. The preliminary results are comparable to those obtained by other registration techniques.
Presents a novel approach to the problem of computer aided analysis of digital mammograms for breast cancer detection: namely, the development of algorithms to recognize unequivocally normal mammograms. First, the aut...
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Presents a novel approach to the problem of computer aided analysis of digital mammograms for breast cancer detection: namely, the development of algorithms to recognize unequivocally normal mammograms. First, the authors eliminate amorphous "clouds" or "blobs" in mammograms produced by normal glandular tissue of varying density using local average subtraction. Then the authors identify and remove normal connective tissue markings based on a set of specially designed line detectors. Any abnormality that may exist in the mammogram is therefore enhanced in the residual image, which makes the decision regarding the normality of the mammogram, much easier.
This paper describes a Virtual Environment system designed to aid in training interventional radiologists in inferior vena cava filter placement. It is being developed as part of a VE simulator for a number of surgica...
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ISBN:
(纸本)9051993862
This paper describes a Virtual Environment system designed to aid in training interventional radiologists in inferior vena cava filter placement. It is being developed as part of a VE simulator for a number of surgical and interventional radiology procedures at the Laboratory for Advanced computer Applications in Medicine at the George Washington University. In this procedure a filter is placed in the inferior vena cava to prevent blood clots from the lower portion of the body from reaching the lungs and causing a pulmonary embolus. The simulation is designed to provide both tutorial and testing modes for the filter placement procedure.
We study the asymptotic behavior of the dual filters associated with biorthogonal spline wavelets (BSWs) and general biorthogonal Coifman wavelets (GBCWs). As the order of wavelet systems approaches infinity the BSW f...
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We study the asymptotic behavior of the dual filters associated with biorthogonal spline wavelets (BSWs) and general biorthogonal Coifman wavelets (GBCWs). As the order of wavelet systems approaches infinity the BSW filters either diverge or converge to some non-ideal filters, the GBCW synthesis filters converge to an ideal halfband lowpass (HBLP) filter without exhibiting any Gibbs-like phenomenon, and a subclass of the analysis filters also converge to an ideal HBLP filter but with a one-sided Gibbs-like behavior. The two approximations of the ideal HBLP filter by Daubechies orthonormal wavelet filters and by the GBCW synthesis filters are also compared.
We generalize an existing family of wavelets, coiflets, by replacing the zero-centered vanishing moment condition on scaling functions by a nonzero-centered one in order to obtain a novel class of compactly supported ...
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We generalize an existing family of wavelets, coiflets, by replacing the zero-centered vanishing moment condition on scaling functions by a nonzero-centered one in order to obtain a novel class of compactly supported orthonormal wavelets (we call them generalized coiflets). This generalization offers an additional free parameter i.e., the center of mass of the scaling function, which can be tuned to obtain improved characteristics of the resulting wavelet system such as near-symmetry of the scaling functions and wavelets, near-linear phase of the filter banks, and sampling approximation properties. Therefore, these new wavelets are promising in a broad range of applications in signal processing and numerical analysis.
This paper presents a new method of estimating the distance between regularly-spaced coherent scatterers within soft tissue from backscattered radio-frequency (RF) signals. Periodic components in the RF signal manifes...
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This paper considers the problem of vector tomography on an arbitrary bounded domain in three dimensions. Previous work has given the formulas for the reconstructed scalar and vector potential functions in relation to...
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This paper considers the problem of vector tomography on an arbitrary bounded domain in three dimensions. Previous work has given the formulas for the reconstructed scalar and vector potential functions in relation to the vector field values inside the domain and on the boundary of the domain. Using these formulas. It is shown that the curl-free component can be reconstructed using only one probe measurement, and the divergence-free component can be reconstructed using only two probe measurements. No boundary measurements are necessary.
We propose a class of Gibbs random fields which incorporate geometric information into stochastic image modeling by means of morphological constraints. This class is shown to be capable of modeling shapes with given m...
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We propose a class of Gibbs random fields which incorporate geometric information into stochastic image modeling by means of morphological constraints. This class is shown to be capable of modeling shapes with given morphological size density. Simulation examples illustrate some model properties.
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