Fast object detection in compressed JPEG Images

Object detection in still images has drawn a lot of attention over past few years, and with the advent of Deep Learning impressive performances have been achieved with numerous industrial applications. Most of these deep learning models rely on RGB images to localize and identify objects in the image. However in some application scenarii, images are compressed either for storage savings or fast transmission. Therefore a time consuming image decompression step is compulsory in order to apply the aforementioned deep models. To alleviate this drawback, we propose a fast deep architecture for object detection in JPEG images, one of the most widespread compression format. We train a neural network to detect objects based on the blockwise DCT (discrete cosine transform) coefficients {issued from} the JPEG compression algorithm. We modify the well-known Single Shot multibox Detector (SSD) by replacing its first layers with one convolutional layer dedicated to process the DCT inputs. Experimental evaluations on PASCAL VOC and industrial dataset comprising images of road traffic surveillance show that the model is about $2\times$ faster than regular SSD with promising detection performances. To the best of our knowledge, this paper is the first to address detection in compressed JPEG images

Ninomiya-Victoir scheme: strong convergence, antithetic version and application to multilevel estimators

In this paper, we are interested in the strong convergence properties of the Ninomiya-Victoir scheme which is known to exhibit weak convergence with order 2. We prove strong convergence with order $1/2$. This study is aimed at analysing the use of this scheme either at each level or only at the finest level of a multilevel Monte Carlo estimator: indeed, the variance of a multilevel Monte Carlo estimator is related to the strong error between the two schemes used on the coarse and fine grids at each level. Recently, Giles and Szpruch proposed a scheme permitting to construct a multilevel Monte Carlo estimator achieving the optimal complexity $O\left(\epsilon^{-2}\right)$ for the precision $\epsilon$. In the same spirit, we propose a modified Ninomiya-Victoir scheme, which may be strongly coupled with order $1$ to the Giles-Szpruch scheme at the finest level of a multilevel Monte Carlo estimator. Numerical experiments show that this choice improves the efficiency, since the order $2$ of weak convergence of the Ninomiya-Victoir scheme permits to reduce the number of discretization levels

Asymptotic error distribution for the Ninomiya-Victoir scheme in the commutative case

In a previous work, we proved strong convergence with order $1$ of the Ninomiya-Victoir scheme $X^{NV}$ with time step $T/N$ to the solution $X$ of the limiting SDE when the Brownian vector fields commute. In this paper, we prove that the normalized error process $N \left(X - X^{NV}\right)$ converges to an affine SDE with source terms involving the Lie brackets between the Brownian vector fields and the drift vector field. This result ensures that the strong convergence rate is actually $1$ when the Brownian vector fields commute, but at least one of them does not commute with the drift vector field. When all the vector fields commute the limit vanishes. Our result is consistent with the fact that the Ninomiya-Victoir scheme solves the SDE in this case.Comment: arXiv admin note: text overlap with arXiv:1601.0526

Lyon (5e) – 23-29 chemin de Montauban, Le Clos de la Solitude

Les sondages archéologiques effectués sur le clos de la Solitude ont été proposés dans le cadre d’une thèse de doctorat portant sur l’architecture domestique à Lugudunum et dirigée par M. Poux et A. Desbat, à l’Université Lyon 2. Ils font suite à la reprise du mobilier issu des fouilles anciennes menées sur le site par le personnel de l’école. Ces sondages, au nombre de trois, ont porté sur la moitié sud de la propriété et avaient pour objectif d’étudier de manière exhaustive les matériaux et..

Lyon (5e) – Clos de la Visitation

Le programme trisannuel de fouille archéologique du Clos de la Visitation (Lyon 5e) a pour objectif d’étudier de manière exhaustive un complexe militaire appartenant sans doute au camp de la Cohorte urbaine de la Colonia Lugudunum. Il a été initié en 2019 par une première campagne de fouille qui a essentiellement concerné les niveaux les plus récents de ce complexe, en lien avec la Bataille de Lyon et le sac de la ville par les troupes de Septime Sévère. Il s’est poursuivi en 2021 sur la mê..

ARCADE 3D-audio codec: an implementation for the web

This poster introduces the implementation of the ARCADE 3D audio codec for web browsers. ARCADE can embed a full 3D audio scene in a simple stereo-compatible audio stream that can be further compressed with standard lossy compression schemes, aired to analog or digital radio receivers or even stored on analog supports. An ARCADE-encoded stream can be decoded to any 2D or 3D-audio rendering format, for instance using Vector-Based Amplitude Panning (VBAP), Higher Order Ambisonics (HOA), or personalized binaural with head tracking. ARCADE adapts seamlessly to the audio industry needs, from storage to production, distribution/delivery, and rendering. It finds uses in Virtual or Augmented Reality (VR/AR), movies, gaming, music, telepresence & teleconferencing. We present a JavaScript (JS) and Web Audio API implementation of the ARCADE decoder, which was originally written in C++11, along with technical details of the porting operations. Live demos of 3D-audio content transmission, decoding and dynamic binaural rendering will be given during the poster session

Properties of galaxies at the faint end of the Hα\alpha luminosity function at z∼0.62z\sim0.62

Studies measuring the star formation rate density, luminosity function, and properties of star-forming galaxies are numerous. However, it exists a gap at $0.5<z<0.8$ in H$\alpha$-based studies. Our main goal is to study the properties of a sample of faint H$\alpha$ emitters at $z\sim0.62$. We focus on their contribution to the faint end of the luminosity function and derived star formation rate density, characterising their morphologies and basic photometric and spectroscopic properties. We use a narrow-band technique in the near-infrared, with a filter centred at 1.06 $\mu$m. The data come from ultra-deep VLT/HAWK-I observations in the GOODS-S field with a total of 31.9 h in the narrow-band filter. We perform a visual classification of the sample and study their morphologies from structural parameters available in CANDELS. Our 28 H$\alpha$-selected sample of faint star-forming galaxies reveals a robust faint-end slope of the luminosity function $\alpha=-1.46_{-0.08}^{+0.16}$. The derived star formation rate density at $z\sim0.62$ is $\rho_\mathrm{SFR} = 0.036_{-0.008}^{+0.012} M_{\odot}~\mathrm{yr^{-1}~Mpc^{-3}}$. The sample is mainly composed of disks, but an important contribution of compact galaxies with S\'ersic indexes $n\sim2$ display the highest specific star formation rates. The luminosity function at $z\sim0.62$ from our ultra-deep data points towards a steeper $\alpha$ when an individual extinction correction for each object is applied. Compact galaxies are low-mass, low-luminosity, and starburst-dominated objects with a light profile in an intermediate stage from early to late types.Comment: Published in Astronomy & Astrophysics. 19 pages, 14 figures. New version includes language edited by the journa

MetExploreViz: web component for interactive metabolic network visualization

Summary: MetExploreViz is an open source web component that can be easily embedded in any web site. It provides features dedicated to the visualization of metabolic networks and pathways and thus offers a flexible solution to analyse omics data in a biochemical context. Availability and implementation: Documentation and link to GIT code repository (GPL 3.0 license) are available at this URL: http://metexplore.toulouse.inra.fr/metexploreViz/doc