On an analytical, spatially-varying, point-spread-function

Roquette, Lucien; Simeoni, Matthieu; Hurley, Paul; Besson, Adrien

doi:10.1109/ultsym.2017.8092301

Cited by 12 publications

(15 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this work, we address the problem of non-stationary deconvolution in US imaging. More precisely, we propose a continuous spatially-varying PSF operator which accounts for diffraction effects related to US propagation and extends the one presented in our previous work [16]. The proposed model is based on a physical modelling of both the US propagation and the DAS, recently discussed in several studies [17], [18].…”

mentioning

confidence: 88%

“…We are now equipped with the two operators D and H that can be injected in (2) to compute the PSF operator. By following similar arguments to the ones developed in [16], K can be decomposed as follows,…”

Section: Delay-and-sum Operatormentioning

confidence: 99%

“…Other approaches estimate directly the PSF on the RF image using homomorphic filtering of the cepstrum [5], [6], [7], inverse filtering based on parametric [8], [9], [10] or non-parametric models [11], [12], [13] and power spectrum equalization [14]. Only few recent studies deal with spatiallyvarying PSF [15], [16]. But, the proposed methods are either too restrictive in the class of functions the PSF belongs to [15] or too computationally expensive to be used in realistic imaging scenarios [16].…”

mentioning

confidence: 99%

“…Only few recent studies deal with spatiallyvarying PSF [15], [16]. But, the proposed methods are either too restrictive in the class of functions the PSF belongs to [15] or too computationally expensive to be used in realistic imaging scenarios [16].…”

mentioning

confidence: 99%

See 3 more Smart Citations

A Physical Model of Nonstationary Blur in Ultrasound Imaging

Besson

Roquette

Perdios

et al. 2019

IEEE Trans. Comput. Imaging

Self Cite

View full text Add to dashboard Cite

Pulse-echo ultrasound (US) aims at imaging tissue using an array of piezoelectric elements by transmitting short US pulses and receiving backscattered echoes. Conventional US imaging relies on delay-and-sum (DAS) beamforming which retrieves a radio-frequency (RF) image, a blurred estimate of the tissue reflectivity function (TRF). To address the problem of the blur induced by the DAS, deconvolution techniques have been extensively studied as a post-processing tool for improving the resolution. Most approaches assume the blur to be spatially invariant, i.e. stationary, across the imaging domain. However, due to physical effects related to the propagation, the blur is nonstationary across the imaging domain. In this work, we propose a continuous-domain formulation of a model which accounts for the diffraction effects related to the propagation. We define a PSF operator as a sequential application of the forward and adjoint operators associated with this model, under some specific assumptions that we precise. Taking into account this sequential structure, we exploit efficient formulations of the operators in the discrete domain and provide a PSF operator which exhibits linear complexity with respect to the grid size. We use the proposed model in a maximum-a-posteriori estimation algorithm, with a generalized Gaussian distribution prior for the TRF. Through simulations and in-vivo experimental data, we demonstrate its superiority against state-of-the-art deconvolution methods based on a stationary PSF.

show abstract

mentioning

confidence: 88%

Section: Delay-and-sum Operatormentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

A Physical Model of Nonstationary Blur in Ultrasound Imaging

Besson

Roquette

Perdios

et al. 2019

IEEE Trans. Comput. Imaging

Self Cite

View full text Add to dashboard Cite

show abstract

“…To overcome this issue, ultrasound images are generally divided in local regions prior to deconvolution, assuming a block-wise spatiallyinvariant PSF (see, e.g., [11]). To avoid issues related to stitching together the results of block-wise techniques, a few attempts have been very recently made in [12] and [13] to account for non-stationary convolution models in ultrasound imaging. The former relies on a very restrictive model with few degrees of freedom whereas the deconvolution method in the latter is computationally intractable for large images.…”

mentioning

confidence: 99%

Restoration of Ultrasound Images Using Spatially-Variant Kernel Deconvolution

Flarea

Basarab

Kouamé

et al. 2018

2018 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)

View full text Add to dashboard Cite

Near-infrared time-series photometry in the field of Cygnus OB2 association

Roquette

Bouvier

Alencar

et al. 2017

A&A

View full text Add to dashboard Cite

Context. In the last decades, the early pre main sequence stellar rotational evolution picture has been constrained by studies targetting different regions at a variety of ages with respect to young star formation. Observational studies suggest a dependence of rotation with mass, and for some mass ranges a connection between rotation and the presence of a circumstellar disk. Not still fully explored, though, is the role of environmental conditions on the rotational regulation.Aims. We investigate the rotational properties of candidate members of the young massive association Cygnus OB2. By evaluating their rotational properties, we address questions regarding the effect of environment properties on PMS rotational evolution.Methods. We studied JHK-band variability in 5083 candidate members (24% of them are diskbearing stars). The selection of variable stars was done using Stetson variability index, and period search was performed using Lomb-Scargle periodogram for periods between 0.83-45 days. Period detections were verified by using False Alarme Probability levels, the Saunders statistics, string/rope length method, and visual verification of folded light curves.Results. We identified 1224 periodic variable stars (24% of the candidate member sample, 8% of the disk-bearing sample, and 28% of the non-disked sample). Monte Carlo simulations were performed in order to evaluate completeness and contamination of the periodic sample, out of which 894 measured periods were considered reliable. Our study was considered reasonably complete for periods between 2 and 30 days. Conclusions. The general scenario for the rotational evolution of young stars seen in other regions is confirmed by Cygnus OB2 period distributions, with disked stars rotating on average slower than non-disked stars. A mass-rotation dependence was also verified, but as in NGC 6530, very low mass stars (M ≤ 0.4M ) are rotating on average slower than higher mass stars (0.4 M < M ≤ 1.4M ). We observed an excess of slow rotators among the lower mass population. The disk and mass-rotation connection was also analysed by taking into account the incident UV radiation arising from O stars in the association. Results compatible with the disk-locking scenario were verified for stars with low UV incidence, but no statistical significant relation between rotation and disk presence was verified for stars with high UV incidence suggesting that massive stars can have an important role on regulating the rotation of nearby low mass stars.Key words. infrared: stars -stars: variables: T Tauri -stars: low-mass -stars: formation -stars: pre main sequence -stars: rotation Use \titlerunning to supply a shorter title and/or \authorrunning to supply a shorter list of authors.

show abstract

On an analytical, spatially-varying, point-spread-function

Cited by 12 publications

References 11 publications

A Physical Model of Nonstationary Blur in Ultrasound Imaging

A Physical Model of Nonstationary Blur in Ultrasound Imaging

Restoration of Ultrasound Images Using Spatially-Variant Kernel Deconvolution

Near-infrared time-series photometry in the field of Cygnus OB2 association

Contact Info

Product

Resources

About