Discretization of image restoration problems often leads to a discrete inverse ill-posed problem: the discretized operator is so badly conditioned that it can be actually considered as undetermined. In this case one s...
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Scratches are one of the most frequent defects appearing in digital film restoration, usually resolved as missing information in subsequent frames of an image sequence in a vertical area of each frame. We describe som...
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Scratches are one of the most frequent defects appearing in digital film restoration, usually resolved as missing information in subsequent frames of an image sequence in a vertical area of each frame. We describe some methods for line scratch removal in digital image sequences, based on the idea of using an image model as simple as possible in order to interpolate scratch pixels, evaluating the displacement of such model from the real model in a neighbourhood of the scratch not affected by the defect, and correcting the reconstruction by adding the estimated displacement. Experimental results on real images are shown.
VRML is the standard language to build a virtual reality system, i.e. a language to describe 3D objects and interactive worlds. To use such a system, among the other tools, a browser is needed in order to access the i...
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VRML is the standard language to build a virtual reality system, i.e. a language to describe 3D objects and interactive worlds. To use such a system, among the other tools, a browser is needed in order to access the information in the VRML files and to visualize the virtual world from a human perspective. This paper describes the implementation of a VRML parallel browser based on a modified version of graphics libraries, such as OpenGL and GLUT. The obtained interactive parallel rendering engine has been developed for a message passing computing environment; a detailed analysis of its performance on a PC cluster is also described.
Discusses the possible use of the fast wavelet transform in order to develop effective preconditioners as well as efficient regularization schemes for image restoration.
Discusses the possible use of the fast wavelet transform in order to develop effective preconditioners as well as efficient regularization schemes for image restoration.
The problem of removing or minimizing degradations in a blurred and noisy image is known as image restoration. The computational kernel of many image restoration problems is the solution of the following inverse probl...
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The problem of removing or minimizing degradations in a blurred and noisy image is known as image restoration. The computational kernel of many image restoration problems is the solution of the following inverse problem: Hf=g+/spl eta/ where where the n/sup 2/-vectors f and g represent the real and the observed image, respectively. The n/sup 2/ vector /spl eta/ is an additive noise which is usually unknown. The n/sup 2//spl times/ n/sup 2/-matrix H is the point spread function matrix and it represents the blurring process. The inverse problem consists in the computation of an approximation to the original image vector f, from known values of g and H. In such cases the restoration problem typically leads to a discrete ill-posed inverse problem. The classical way to compute a reasonable solution is to regularize the discrete problem. We explore the possible use of the fast wavelet transform-based preconditioners for the efficient solution of image restoration problems.
The parallel Naples airshed model (PNAM) is a parallel software package for the numerical simulation of photosmog episodes in urban scale domains. It solves the atmospheric diffusion equations, which model the air pol...
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The parallel Naples airshed model (PNAM) is a parallel software package for the numerical simulation of photosmog episodes in urban scale domains. It solves the atmospheric diffusion equations, which model the air pollution dynamics in a Eulerian approach, using a symmetric time‐splitting, where the advection is separated from the (coupled) diffusion and chemistry. Presents some results of a numerical simulation of a severe photochemical smog episode, which occurred in the Naples area. A preliminary comparison with measured data is reported, as a first step toward the validation of PNAM. Some parallel performance results, obtained on an IBM SP machine, are also shown.
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