Nicolas GAC

MCF HDR / Associate Professor - Université Paris Saclay - GPI team

L2S, CentraleSupélec
Bât. Breguet C4.19
3 rue Joliot Curie
91190 Gif-sur-Yvette, France

+33 (0)1 69 85 17 38

Publications

TeachingPh.D./InternshipAgendaTalksBioProjects
2023
Chapitres d’ouvrages scientifiques

Prototypage rapide d’un supercalculateur dédié à la radioastronomie

Gac, Nezan, Ferrari, Ferrari, Quinson, Dumez-Viou
in L’Interdisciplinarité. Voyages au-delà des disciplines, CNRS Edition, 2023
2022
Articles dans des revues

Real-Time Optical Flow Processing on Embedded GPU: a Hardware-Aware Algorithm to Implementation Strategy

Seznec, Gac, Orieux, Naik
Journal of Real-Time Image Processing, 19 (2), p. 317-329, 2022

Computing Large 2D Convolutions on GPU Efficiently with the im2tensor Algorithm

Seznec, Gac, Orieux, Naik
Journal of Real-Time Image Processing, 19, p. 1035-1047, 2022
Communications dans des congrès

Fast Sky to Sky Interpolation for Radio Interferometric Imaging

Monnier, Orieux, Gac, Tasse, Raffin, Guibert
IEEE International Conference on Image Processing (ICIP), Bordeaux, France, 2022

Premiers résultats de comparaison des outils oneAPI et OpenCL pour la convolution 2D sur FPGA

Diakite, Gac
28ème Colloque Francophone de Traitement du Signal et des Images GRETSI 2022, Nancy, France, 2022

MobileFlow : modèle et mise en œuvre pour une inférence de flot optique efficace

Seznec, Archet, Gac, Orieux, Naik
28eme Colloque GRETSI Traitement du Signal & des Images, Nancy, France, 2022

Interpolation Rapide Sky to Sky pour l’Imagerie Radio Interférométrique

Monnier, Orieux, Gac, Guibert, Tasse, Raffin
GRETSI 28ème Colloque Francophone de Traitement du Signal et des Images, Nancy, France, 2022

FPGA implementation of 2D Convolution using OneAPI and OpenCL

Diakite, Gac
16ème Colloque National du GDR SOC2, Strasbourg, France, 2022

Multi-core multi-node parallelization of the radio interferometric imaging pipeline DDFacet

Monnier, Guibert, Tasse, Gac, Orieux, Raffin, Smirnov, Hugo
IEEE Workshop on Signal Processing Systems (SiPS), Rennes, France, 2022
Posters

Les télélescopes SKA

Monnier, Gac, Orieux
Fête de la science, Saclay, France, 2022
2021
Communications dans des congrès

Memory prefetching for tomography acceleration on FPGAs through HLS tools

Diakite, Gac
15ème Colloque National du GDR SOC2, Rennes, France, 2021

OpenCL FPGA Optimization guided by memory accesses and roofline model analysis applied to tomography acceleration

Diakite, Gac, Martelli
31st International Conference on Field Programmable Logic and Applications (FPL), Dresden (virtual), Allemagne, 2021
Posters

Dataflow Algorithm aRchitecture co-design of SKA pipeline for Exascale Radio Astronomy

Charlet, Desnos, Dardaillon, Ferrari, Ferrari, Gac, Nezan, Orieux, Prunet, Quinson, Suter, Tasse, Dumez-Viou
ISC High Performance 2021, Virtual conference, France, 2021
2020
Communications dans des congrès

An efficiency-driven approach for real-time optical flow processing on parallel hardware

Seznec, Gac, Orieux, Naik
IEEE International Conference on Image Processing, Abu Dhabi, Émirats arabes unis, 2020

Data distribution on a multi-GPU node for TomoBayes CT reconstruction

Chghaf, Gac
The 26th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, Inconnu, Corée du Sud, 2020

An OpenCL pipeline implementation on Intel FPGA for 3D backprojection

Diakite, Martelli, Gac
6th International Conference on Image Formation in X-Ray Computed Tomography, Regensburg, Allemagne, 2020
H.D.R.
Posters

A new convolutions algorithm to leverage tensor cores

Seznec, Gac, Orieux, Naik
GPU Technology Conference (GTC), Silicon Valley, États-Unis, 2020
2019
Articles dans des revues

ROHSA: Regularized Optimization for Hyper-Spectral Analysis

Marchal, Miville-Deschênes, Orieux, Gac, Soussen, Lesot, Revault d’Allonnes, Salomé
Astron. Astrophys. – A&A, 626, EDP Sciences, p. A101, 2019

Error-Splitting Forward Model for Iterative Reconstruction in X-ray Computed Tomography and application with Gauss-Markov-Potts prior

Chapdelaine, Mohammad-Djafari, Gac, Parra
IEEE Transactions on Computational Imaging, 5 (2), p. 317 – 332, 2019

3D Tomography back-projection parallelization on Intel FPGAs using OpenCL

Martelli, Gac, Mérigot, Enderli
Journal of Signal Processing Systems, 91 (7), p. 1939-8115, 2019
Communications dans des congrès

Accélération sur GPU d’une simulation radar avec OpenACC

Martelli, Enderli, Gac, Vermesse, Mérigot
GRETSI 2019 – XXVIIème Colloque francophone de traitement du signal et des images, Lille, France, 2019

Multi-streaming and multi-GPU optimization for a matched pair of Projector and Backprojector

Georgin, Chapdelaine, Gac, Mohammad-Djafari, Parra-Denis
The 2019 International Conference on Fully Three-Dimensional Image Reconstruction in Radiology and Nuclear Medicine, Philadelphie, PA, États-Unis, 2019

GPU Acceleration : OpenACC for Radar Processing Simulation

Martelli, Enderli, Gac, Vermesse, Mérigot
International Radar Conference, Toulon, France, 2019

Variational Bayesian approach in model-based iterative reconstruction for 3D X-ray computed tomography with Gauss-Markov-Potts prior

Chapdelaine, Mohammad-Djafari, Gac, Parra-Denis
MaxEnt 2019 : Workshop on Bayesian Inference and Maximum Entropy Methods in Science and Engineering, Garching/Munich, Allemagne, 2019
Autre documents

TomoBayes – logiciel de reconstruction en tomographie CT

Chapdelaine, Gac, Boulay, Mohammad-Djafari, Parra-Denis, Le Guilloux, Georgin
2019
2018
Articles dans des revues
Communications dans des congrès

Harnessing FPGAs potential with OpenCL

Martelli, Gac, Mérigot, Enderli
13ème Colloque nationale du GDR SoC/SiP, Paris, France, 2018

New GPU implementation of Separable Footprint (SF) Projector and Backprojector : first results

Chapdelaine, Gac, Djafari, Parra-Denis
The Fifth International Conference on Image Formation in X-Ray Computed Tomography, Salt Lake City, États-Unis, 2018

Bayesian Inference with Error Variable Splitting and Sparsity Enforcing Priors for Linear Inverse Problems

Mohammad-Djafari, Dumitru, Chapdelaine, Gac
26th European Signal Processing Conference (EUSIPCO 2018), Rome, Italie, 2018

A Study on Convolution Operator Using Half Precision Floating Point Numbers on GPU for Radioastronomy Deconvolution

Seznec, Gac, Ferrari, Orieux
IEEE International Workshop on Signal Processing Systems (SiPS 2018), Le Cap, Afrique du Sud, 2018
Brevets

Procédé et dispositif de contrôle non-destructif d’une pièce

Chapdelaine, Mohammad-Djafari, Parra-Denis, Gac
France, Patent n° : 18/53648, 2018
Ouvrages scientifiques

French SKA White Book – The French Community towards the Square Kilometre Array

Acero, Acquaviva, Adam, Aghanim, Allen, Alves, Ammanouil, Ansari, Araudo, Armengaud, Ascaso, Athanassaoula, Aubert, Babak, Bacmann, Banday, Barriere, Bellossi, Bernard, Bernardini, Bethermin, Blanc, Blanchet, Bobin, Boissier, Boisson, Boselli, Bosma, Bosse, Bottinelli, Boulanger, Boyer, Bracco, Briand, Bucher, Buat, Cambresy, Caillat, Casandjian, Caux, Celestin, Cerruti, Charlot, Chassande-Mottin, Chaty, Christensen, Ciesla, Clerc, Cohen-Tanugi, Cognard, Combes, Comis, Corbel, Cordier, Coriat, Courtin, Courtois, da Silva, Daddi, Dallier, Dartois, Demyk, Denis, Denis, Djannati-Atai, Donati, Douspis, van Driel, Korso, Falgarone, Fantina, Farges, Ferrari, Ferrari, Ferrière, Flamary, Gac, Gauffre, Genova, Girard, Grenier, Griessmeier, Guillard, Guillemot, Gulminelli, Gusdorf, Habart, Hammer, Hennebelle, Herpin, Hervet, Hughes, Ilbert, Janvier, Josselin, Julier, Lachaud, Lagache, Lallement, Lambert, Lamy, Larzabal, Lavaux, Bertre, Fèvre, Tiec, Lefloch, Lehnert, Lemoine-Goumard, Levrier, Limousin, Lis, López-Sepulcre, Macías-Pérez, Magneville, Marcowith, Margueron, Marquette, Marshall, Martin, Mary, Masson, Maurogordato, Mazauric, Mellier, Miville-Deschênes, Montier, Mottez, Mourard, Nesvadba, Nezan, Noterdaeme, Novak, Ocvirk, Oertel, Olive, Ollier, Palanque-Delabrouille, Pandey-Pommier, Pennec, Perault, Peroux, Petit, Petri, Petiteau, Pety, Pratt, Puech, Quertier, Raffin, Harison, Rawson, Renaud, Revenu, Richard, Richard, Rincon, Ristorcelli, Rodriguez, Schultheis, Schimd, Semelin, Sol, Starck, Tagger, Tasse, Theureau, Torchinsky, Vastel, Vergani, Verstraete, Vigouroux, Vilmer, Vilotte, Webb, Ysard, Zarka, Langer
2018
Autre documents
2017
Articles dans des revues

X-ray Computed Tomography using a sparsity enforcing prior model based on Haar transformation in a Bayesian framework

Wang, Mohammad-Djafari, Gac
Fundamenta Informaticae, 155 (4), p. 449-480, 2017

A 3D Bayesian Computed Tomography Reconstruction Algorithm with Gauss-Markov-Potts Prior Model and its Application to Real Data

Chapdelaine, Mohammad-Djafari, Gac, Parra-Denis
Fundamenta Informaticae, 155 (4), p. 373-405, 2017
Communications dans des congrès

Bayesian X-ray Computed Tomography using a Three-level Hierarchical Prior Model

Wang, Mohammad-Djafari, Gac
AIP Conference, Bayesian inference and maximum entropy methods in science and engineering (Maxent 2016), Gent, Belgique, 2017

X-ray computed tomography simultaneous image reconstruction and contour detection using a hierarchical markovian model

Wang, Mohammad-Djafari, Gac
The 42nd IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP 2017), New Orleans, États-Unis, 2017

A joint segmentation and reconstruction algorithm for 3D Bayesian Computed Tomography using Gaus-Markov-Potts Prior Model

Chapdelaine, Mohammad-Djafari, Gac, Parra-Denis
The 42nd IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP 2017), New Orleans, États-Unis, 2017

3D X-ray Computed Tomography reconstruction using sparsity enforcing Hierarchical Model based on Haar Transformation

Wang, Mohammad-Djafari, Gac, Dumitru
The 2017 International Conference on Fully Three-Dimensional Image Reconstruction in Radiology and Nuclear Medicine, Xi’an, Chine, 2017

Unsupervised sparsity enforcing iterative algorithms for 3D image reconstruction in X-ray computed tomography

Dumitru, Gac, Wang, Mohammad-Djafari
The 2017 International Conference on Fully Three-Dimensional Image Reconstruction in Radiology and Nuclear Medicine, Xi’an, Chine, 2017

Bayesian method with sparsity enforcing prior of dual-tree complex wavelet transform coefficients for X-ray CT image reconstruction

Wang, Mohammad-Djafari, Gac
25th European Signal Processing Conference (EUSIPCO 2017), Kos island, Grèce, 2017

Comparaison des performances d’algorithmes itératifs bayésiens basés sur trois classes de modèles a priori parcimonieux appliqués à la reconstruction tomographique

Dumitru, Wang, Gac, Mohammad-Djafari
26eme Colloque GRETSI Traitement du Signal & des Images, GRETSI 2017, Juans-Les-Pins, France, 2017

Reconstruction 3D en tomographie à rayons X à l’aide d’un modèle a priori hiérarchique utilisant la transformation de Haar

Wang, Gac, Mohammad-Djafari
26eme Colloque GRETSI Traitement du Signal & des Images, GRETSI 2017, Juan-Les-Pins, France, 2017

Performance comparison of Bayesian iterative algorithms for three classes of sparsity enforcing priors with application in computed tomography

Dumitru, Li, Gac, Mohammad-Djafari
2017 IEEE International Conference on Image Processing, Beijing, Chine, 2017

3D Tomography parallelization on FPGAs via HLS tools

Martelli, Gac, Mérigot, Enderli
DASIP, dresden, Allemagne, 2017

Model selection in the sparsity context for inverse problems in Bayesian framework

Dumitru, Wang, Mohammad-Djafari, Gac
37th International Workshop on Bayesian Inference and Maximum Entropy Methods in Science and Engineering, Jarinu, Brésil, 2017
Posters

An OpenCL design for tomographic reconstruction on FPGA. Innovate Europe Design Contest Winners

Martelli, Seznec, Heemeryck, Gac
27th international conference on field programmable logic and applications, Ghent, Belgique, 2017
2016
Communications dans des congrès

A Student-t based sparsity enforcing hierarchical prior for linear inverse problems and its efficient Bayesian computation for 2D and 3D Computed Tomography

Mohammad-Djafari, Wang, Gac, Bleichrodt
International traveling workshop on interactions between sparse models and technology, AALBORG, Danemark, 2016

Computed tomography reconstruction based on a hierarchical model and variational Bayesian method

Wang, Mohammad-Djafari, Gac, Dumitru
IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), Shanghai, Chine, 2016
2015

A hierarchical variational Bayesian approximation approach in acoustic imaging

Chu, Mohammad-Djafari, Gac, Picheral
34th International Workshop on Bayesian Inference and Maximun Entropy Methods in Science and Engineering (MaxEnt’14), Amboise, France, 2015

Bayesian 3D X-ray computed tomography image reconstruction with a scaled Gaussian mixture prior model

Wang, Gac, Mohammad-Djafari
34th International Workshop on Bayesian Inference and Maximun Entropy Methods in Science and Engineering (MaxEnt’14), Amboise, France, 2015
2014
Articles dans des revues

Toward a numerical deshaker for PFS

Schmidt, Shatalina, Kowalski, Gac, Saggin, Giuranna
Planetary and Space Science, 91, p. 45 – 51, 2014

A robust super-resolution approach with sparsity constraint in acoustic imaging

Chu, Picheral, Mohammad-Djafari, Gac
Applied Acoustics, 76, Elsevier, p. 197-208, 2014
Communications dans des congrès

2D convolution model using (in)variant kernels for fast acoustic imaging

Chu, Gac, Picheral, Mohammad-Djafari
5 th Berlin Beamforming Conference 2014, Berlin, Allemagne, 2014

Aero-acoustics source separation with sparsity inducing priors in the frequency domain

Schwander, Picheral, Gac, Djafari, Blacodon
34th International Workshop on Bayesian Inference and Maximun Entropy Methods in Science and Engineering (MaxEnt’14), Amboise, France, 2014

A simple and efficient super-short-scan algorithm of fan-beam reconstruction for multiple circular trajectories: solution towards the truncated data

Chen, Rodet, Gac
The Third International Conference on Image Formation in X-Ray Computed Tomography, Salt Lake City, États-Unis, 2014

A variational Bayesian approximation approach via a sparsity enforcing prior in acoustic imaging

Chu, Mohammad-Djafari, Gac, Picheral
WIO 2014, Neuchâtel, Suisse, 2014

Convolution Models with Shift-invariant kernel based on Matlab-GPU platform for Fast Acoustic Imaging

Chu, Gac, Picheral, Mohammad-Djafari
ISAV 2014, Tehran, Iran, 2014
Autre documents
2013
Articles dans des revues

Algorithmes de reconnaissance NCTR et parallélisation sur GPU

Boulay, Gac, Mohammad-Djafari, Lagoutte
Trait. Signal, 6, Lavoisier, p. 309-342, 2013
Communications dans des congrès

An efficient variational Bayesian inference approach via Studient’s-t priors for acoustic imaging in colored noises

Chu, Mohammad-Djafari, Picheral, Gac
Proceedings of the 21st International Congress on Acoustics, Montreal, Canada, 2013

Analytical model and spectral correction of vibration effects on Fourier transform spectrometer

Shatalina, Schmidt, Saggin, Gac, Kowalski, Giuranna
SPIE Remote sensing 2013, Dresden, Allemagne, 2013

A penalized weighted least-squares image reconstruction based on scatter correction methods for X-ray CT

Chen, Rodet, Gac
2013 IEEE Nuclear Science Symposium and Medical Imaging Conference, Seoul, Corée du Sud, 2013
2012
Articles dans des revues

Experimental results and first 22Na source image reconstruction by two prototype modules in coincidence of a liquid xenon positron emission tomograph for small animal imaging

Gallin-Martel, Grondin, Gac, Carcagno, Gallin-Martel, Grondin, Marton, Muraz, Rossetto, Vezzu
Nucl. Instr.& Meth. Phys. A, 682, Elsevier, p. 66-74, 2012
Communications dans des congrès

A Fuzzy-Logic based non cooperative target recognition

Boulay, Lagoutte, Mohammad-Djafari, Gac
2012 Eighth International Conference on Signal Image Technology and Internet Based Systems, Naples, Italie, 2012
Posters

Parallelization on a 8-GPU server of iterative 3D reconstruction algorithm for dental X-ray tomography

Chen, Gac, Rodet, Maury
PUMPS summer school, Barcelone, Espagne, 2012
2011
Communications dans des congrès

Multi GPU parallelization of 3D bayesian CT algorithm and its application on real foam reonconstruction with incomplete data set

Gac, Vabre, Mohammad-Djafari
Forum on recent developments in Volume Reconstruction techniques applied to 3D fluid and solid mechanics, Poitiers, France, 2011

Accélération sur serveur multi-GPUs de la reconstruction 3D d’une mousse de nickel par méthodes itératives algébriques régularisées

Gac, Vabre, Mohammad-Djafari, Buyens
23ème colloque GRETSI sur le traitement du signal et des images, Bordeaux, France, 2011

Algorithmes de Reconnaissance Non Coopérative de Cibles et implémentation sur GPU

Boulay, Gac, Mohammad-Djafari, Lagoutte
GRETSI, Bordeaux, France, 2011
Posters
2010
Communications dans des congrès

GPU implementation of a 3D bayesian CT algorithm and its application on real foam reconstruction

Gac, Vabre, Mohammad-Djafari, Rabanal, Buyens
The 1st CT Meeting Proceedings, Salt Lake City, États-Unis, 2010
Posters

[OMTE 2008/2009] GPU speed-up of a 3D Bayesian CT algorithm : reconstruction of a real foam

Gac, Rabanal, Vabre, Mohammad-Djafari
Forum Digiteo, Palaiseau, France, 2010
2009
Communications dans des congrès

Parallélisation sur GPU d’un algorithme de reconstruction 3D bayésien en tomographie X.

Gac, Vabre, Mohammad-Djafari, Buyens, Legoupil
Développement d’applications de calcul intensif sur carte graphique pour l’imagerie moléculaire, Obernai, France, 2009
2008
Articles dans des revues

High Speed 3D Tomography on CPU, GPU, and FPGA

Gac, Mancini, Desvignes, Houzet
EURASIP Journal on Embedded Systems, 2008, p. http://www.hindawi.com/GetArticle.aspx?doi=10.1155/2008/930250, 2008
Communications dans des congrès

A Hardware Projector/Backprojector Pair for 3D PET Reconstruction

Gac, Mancini, Desvignes, de Boissieu, Reilhac
SPIE Medical Imaging 2008, San Diego, Californie, États-Unis, 2008
Thèses

Adéquation Algorithme Architecture pour la reconstruction 3D en imagerie médicale TEP

Gac
Institut National Polytechnique de Grenoble – INPG, 2008
2007
Communications dans des congrès

Algorithm Architecture Adequacy for High Speed 3D Tomography

Gac, Mancini, Desvignes, Houzet
DASIP 2007 – Workshop on Design and Architectures for Signal and Image Processing, Grenoble, France, 2007
2006
Articles dans des revues

Application d’un cache 2D prédictif à l’accélération de la rétroprojection TEP 2D

Mancini, Gac, Desvignes, Bourrion, Rossetto
Trait. Signal, 23, Lavoisier, p. Numéro 5-6, 2006
Communications dans des congrès

Hardware/software 2D-3D backprojection on a SoPC platform

Gac, Mancini, Desvignes
ACM Symposium on Applied Computing, Dijon, France, 2006
2005

Rétroprojection 2D sur plateforme SOPC

Mancini, Gac, Desvignes
GRETSI’05, Louvain-la-neuve, Belgique, 2005

Detection and Speech/Sound Segmentation in a Smart Room Environment

Vacher, Istrate, Serignat, Gac
Trends in Speech Technology, The 3rd International Conference on Speech Technology and Human-Computer Dialogue, IEEE, SpeD2005, Cluj, Roumanie, 2005

2D backprojection on a SOPC platform : first results

Mancini, Gac, Desvignes
13 ème Forum Recherche en Génie Biologique et Médica, Nancy, France, 2005

Etude d’un cache 2D adaptatif et prédictif pour le traitement d’image

Mancini, Gac, Desvignes
Journées Francophones en Adéquation Algorithme Architecture, Dijon, France, 2005