Search results for "Algorithm"
showing 10 items of 4887 documents
Superresolved imaging of remote moving targets.
2006
We present a superresolving approach that allows one to exceed the diffraction limit and recover highly resolved contours of moving targets from a sequence of low-resolution images. The presented approach is suitable for remote sensing applications. The resolution decoding algorithm that is used to recover the high-resolution features of the target can be run partially via optical means and that way can be used to reduce the required computational complexity.
Quasi-spherical focal spot in two-photon scanning microscopy by three-ring apodization
2005
International audience; We present a beam-shaping technique for two-photon excitation (TPE) fluorescence microscopy. We show that by inserting a properly designed three-ring pupil filter in the illumination beam of the microscope, the effective optical sectioning capacity of such a system improves so that the point spread function gets a quasi-spherical shape. Such an improvement, which allows the acquisition of 3D images with isotropic quality, is obtained at the expense of only a small increase of the overall energy in the axial sidelobes. The performance of this technique is illustrated with a scanning TPE microscopy experiment in which the image of small beads is obtained. We demonstrat…
Variational multiframe restoration of images degraded by noisy (stochastic) blur kernels
2013
This article introduces and explores a class of degradation models in which an image is blurred by a noisy (stochastic) point spread function (PSF). The aim is to restore a sharper and cleaner image from the degraded one. Due to the highly ill-posed nature of the problem, we propose to recover the image given a sequence of several observed degraded images or multiframes. Thus we adopt the idea of the multiframe approach introduced for image super-resolution, which reduces distortions appearing in the degraded images. Moreover, we formulate variational minimization problems with the robust (local or nonlocal) L^1 edge-preserving regularizing energy functionals, unlike prior works dealing wit…
Iterative Regularization Techniques in Image Reconstruction
2000
In this survey we review recent developments concerning the efficient iterative regularization of image reconstruction problems in atmospheric imaging. We present a number of preconditioners for the minimization of the corresponding Tikhonov functional, and discuss the alternative of terminating the iteration early, rather than adding a stabilizing term in the Tikhonov functional. The methods are examplified for a (synthetic) model problem.
2021
Abstract We propose a signal deconvolution procedure for imaging spectrometer data, where a measured point spread function (PSF) is deconvolved itself before being used for deconvolution of the signal. We evaluate the effectiveness of our procedure for improvement of the spatio-spectral signal, as well as our target application, i.e. estimation of sun-induced fluorescence (SIF). Imaging spectrometers are well established instruments for remote sensing. When used for scientific purposes these instruments are usually calibrated on a regular basis. In our case the point spread function of the optics is measured in an elaborate procedure with a tunable monochromator point light source. PSFs are…
Pointwise resolutive significance of data and applications in experimental design and data treatment
1992
Abstract The concept of the resolutive significance of a point in a data set with regard to a number of addressed parameters is introduced, and two algorithms able to measure it are proposed. The algorithms are validated using simulated experiments. The sum of all the pointwise resolutive significances of a data set is also proposed as a measure of the resolution of the data set. This sum correlates well with the reciprocal of the standard deviation of the fitted parameters, indicating the precision that can be expected for each parameters. Applications in experimental design, and a method for establishing the weights in the least-quarters regression analysis are discussed.
Characterization of Orlicz–Sobolev space
2007
We give a new characterization of the Orlicz–Sobolev space W1,Ψ(Rn) in terms of a pointwise inequality connected to the Young function Ψ. We also study different Poincaré inequalities in the metric measure space.
Human-technology relations in an age of surveillance capitalism. Towards an anthropological theory of the dialectic between analogue and digital huma…
2021
What can anthropology contribute to the current debates about the negative effects of social media on people? Starting from a critique of anthropological work that sees human subjectivity and culture as ontologically unaffected by social media use, I propose that human engagement with these digital technologies produces significant ontological transformations that deserve more attention. I develop my analysis in dialogue with Boellstorff’s ontology of the digital, Nardi’s theorisation of virtuality and affordances, and Zuboff’s formulation of surveillance capitalism, and I use empirical illustrations from the Cambridge Analytica data scandal to highlight key theoretical junctures. My main c…
Analysing the efficiency of wastewater treatment plants: The problem of the definition of desirable outputs and its solution
2020
Abstract Evaluating the efficiency of wastewater treatment plants (WWTPs) is highly relevant to improve their performance from an economic and environmental perspective. The issue is even more critical in countries where WWTPs are benchmarked to regulate water companies and define WWTPs’ economic and environmental objectives. Despite the large number of previous studies on this topic, none has considered that the amount of outputs produced by the WWTPs is restricted by the concentration of pollutants in the effluent. To overcome this limitation, the study’s main objective was to propose a new variant of the Weighted Russell Directional Distance Model (WRDDM) that would solve problems regard…