Colas Schretter

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Contact
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News

August 27, 2014: I contributed to two works from our group for the iTWIST'14, international - Traveling Workshop on Interactions between Sparse models and Technology, August 27-29, in Namur, Belgium. Abstracts are available in the list of publications below.

May 22, 2014: I will present our most recent results on "Compressed sensing ultrasound imaging with adapted dictionaries of point spread functions" at the FNRS contact group "Wavelets and applications". The meeting is organized in Brussels, by Christine De Mol.

April 6, 2014: I will give a seminar on "Constructing quasi-random points with the golden ratio sequence and the Hilbert space filling curve" at the special session organized by J. Dick and D. Nuyens at the Conference on Monte Carlo and Quasi-Monte Carlo Methods in Scientific Computing, April 6-11, in Leuven, Belgium.

August 2, 2013: I was invited to give a two-hours introductory overview on "Quasi-Random Sequences and Sets" at the Brussels Summer School of Mathematics, 2013. The slides are available online on that page.

February 19, 2013: The patent "Method and apparatus to improve CT image acquisition using a displaced geometry" has been issued on the February 19, 2013 (US Patent No: 8,379,791). It was originally filled on October 5, 2009. IP protection is a very slow process.

Bio

Timeline

I completed the M.Sc. degree in computer science with great honors in 2004 and received an additional Master of advanced studies (DEA) in 2006 from the Université libre de Bruxelles, Belgium. In February 2007, I moved to Germany for a scientist position with Philips Research, Aachen. Meanwhile, I earned a Marie Curie EST fellowship for my doctoral thesis, awarded with magna cum laude in April 2010, at the Otto-von-Guericke University. Thereafter, I won a Marie Curie ERG grant for my postdoctoral project with the RWTH Aachen University and was visiting researcher at the Politecnico di Milano, Italy. I was selected for a M+Vision 2012 fellowship at the MIT in Cambridge, USA. I am now back in Belgium since October 2013, as a iMinds research scientist at the Department of Electronics and Informatics of the Vrije Universiteit Brussel.

Projects

Results

I am developing sparse models and online statistical algorithms for image reconstruction.

Brussels Interest Group on Sparsity (BIGS)

Effective Thinking in C++

Colas' Demomaking

OligoFaktory SE

Click on the images to open linked websites.

Journal papers

Colas Schretter and Harald Niederreiter, A Direct Inversion Method for Non-Uniform Quasi-Random Point Sequences, Monte Carlo Methods and Applications, vol. 19, no. 1, pp. 1–9, 2013. Link

Colas Schretter, Leif Kobbelt and Paul-Olivier Dehaye, Golden Ratio Sequences for Low-Discrepancy Sampling, Journal of Graphics Tools, vol. 16, no. 2, pp. 95–104, 2012. Link

Colas Schretter, Georg Rose and Matthias Bertram, Image-Based Iterative Compensation of Motion Artifacts in Computed Tomography, Medical Physics, vol. 36, no. 11, pp. 5323–5330, 2009. Link

Laurent Gatto and Colas Schretter, Designing Primer Pairs and Oligos with OligoFaktorySE, EMBnet news, vol. 15, no. 3, pp. 22–24, 2009. Link

Colas Schretter, Event-by-Event Image Reconstruction From List-Mode PET Data, IEEE Transactions on Image Processing, vol. 8, no. 1, pp. 117–124, 2009. Link

Patrick E. Meyer, Colas Schretter and Gianluca Bontempi, Information-Theoretic Feature Selection in Microarray Data Using Variable Complementarity, IEEE Journal of Selected Topics in Signal Processing, vol. 2, no. 3, pp. 261–274, 2008. Link

Colas Schretter, A Fast Tube of Response Ray-Tracer, Medical Physics, vol. 33, no. 12, pp. 4744–4748, 2006. Link

Colas Schretter and Michel C. Milinkovitch, OligoFaktory: A Visual Tool for Interactive Oligonucleotide Design, Bioinformatics, vol. 22, no. 1, pp. 115–116, 2006. Paper

Colas Schretter, A Brush Tool for Interactive Texture Synthesis, ICGST International Journal on Graphics, Vision and Image Processing, vol. 6, no. 5, pp. 55–60, 2005. Link

Colas Schretter, Discover OligoFaktory Standalone Edition, EMBnet news, vol. 11, no. 4, pp. 24–25, 2005. Link

Book chapters

Colas Schretter, Zhijian He, Mathieu Gerber and Harald Niederreiter, Van der Corput and Golden Ratio Sequences Along the Hilbert Space-Filling Curve, Monte Carlo and Quasi-Monte Carlo Methods, Springer Verlag, 2014 (to appear).

Dissertations

Colas Schretter, Correction of Non-Periodic Motion in Computed Tomography, Doctoral thesis, Otto-von-Guericke University, Magdeburg, Germany, April, 2010. Link

Colas Schretter, New Algorithms for Image Reconstruction From Emission Tomography List-Mode Data, DEA thesis, Université libre de Bruxelles, Brussels, Belgium, September, 2006.

Colas Schretter, Efficient N-Body Algorithms for Astrophysical Simulations, Master thesis, Université libre de Bruxelles, Brussels, Belgium, June, 2003.

Technical reports

Colas Schretter, Computing Random Points on Sphere, Boost C++ Ticket 1059, June, 2007. Link

Colas Schretter and Laurent Gatto, A Tiny Queuing System for Blast Servers, December, 2005. Link

Colas Schretter and Michel C. Milinkovitch, Automated Long Oligo Design on Consensus Regions of Similar Genomes, Technical Report UEG, IBMM, ULB, 2005.

Colas Schretter and Michel C. Milinkovitch, Oligonucleotide Design by Multilevel Optimization, Technical Report UEG, IBMM, ULB, 2005.

Patents

Colas Schretter, Matthias Bertram and Christoph Neukirchen, Method and Apparatus For Large Field of View Imaging and Detection and Compensation of Motion Artifacts, US 30961/04024, January, 2009. Link

Peter Forthmann, Thomas Koehler, Udo Van Stevendaal, Matthias Bertram, Steffen Hohmann and Colas Schretter, Method and Apparatus to Improve CT Image Acquisition Using Displaced Geometry, US 30961/04021, September, 2008. Link

Invited lectures

Colas Schretter, Constructing Quasi-Random Points with the Golden Ratio Sequence and the Hilbert Space Filling Curve, Conference on Monte Carlo and Quasi-Monte Carlo Methods in Scientific Computing, Leuven, Belgium, April 6-11, 2014. (Joint work with Harald Niederreiter.)

Colas Schretter, Séquences et ensembles quasi-aléatoires, Brussels Summer School of Mathematics (BSSM), Brussels, Belgium, August 1-7, 2013.

Colas Schretter, Jason N. Hill and Martha L. Gray, Wake-Up to Bruxism: Sleep Monitoring and Personalized Audio Feedback on your Smartphone, MIT Future of Health and Wellness Conference, Cambridge, February 6-7, 2013. MIT Sloan BioInnovations Conference, Cambridge, February 22, 2013. Poster

Colas Schretter, Hierarchical B-Spline Mixture Models for TOF-PET Image Reconstruction, M+Vision Open-House, Madrid, Spain, July 19-20, 2012.

Colas Schretter and Leif Kobbelt, Golden Ratio Sequences for Low-Discrepancy Sampling, HiGraphics, Hirschegg, Austria, March 27-31, 2011.

Colas Schretter, Improving Image Quality in Computed Tomography by Motion Estimation and Compensation, 8th IEEE EMBS International Summer School on Biomedical Imaging, Berder, France, June 20-28, 2008.

Conference Papers

Colas Schretter, Ignace Loris, Ann Dooms and Peter Schelkens, Total Variation Reconstruction From Quasi-Random Samples, iTWIST'14, international - Traveling Workshop on Interactions between Sparse models and Technology, Namur, Belgium, August 27-29 2014. Paper

Shaun Bundervoet, Colas Schretter, Ann Dooms and Peter Schelkens, Bayesian Estimation of Sparse Smooth Speckle Shape Models for Motion Tracking in Medical Ultrasound, iTWIST'14, international - Traveling Workshop on Interactions between Sparse models and Technology, Namur, Belgium, August 27-29 2014. Paper

Colas Schretter, Jianyong Sun and Leif Kobbelt, Online Estimation of B-Spline Mixture Models From TOF-PET List-Mode Data, Proc. of the 11th International Meeting on Fully Three-Dimensional Image Reconstruction in Radiology and Nuclear Medicine, Potsdam, Germany, July 11-15, pp. 274–277, 2011. Paper

Se Young Chun, Colas Schretter and Jeffrey A. Fessler, Sufficient Condition for Local Invertibility of Spatio-Temporal 4D B-Spline Deformations, Proc. of the 7th IEEE International Symposium on Biomedical Imaging, Rotterdam, The Netherlands, April 14-17, pp. 1221–1224, 2010. Link, Poster

Colas Schretter, Fabian Pilatus, Georg Rose, Til Aach and Matthias Bertram, Optical Flow Motion Estimation for Approximate Motion Compensation in Cone-Beam CT, Proc. of the 10th International Meeting on Fully Three-Dimensional Image Reconstruction in Radiology and Nuclear Medicine, Beijing, China, September 5-10, pp. 327–330, 2009. Paper

Colas Schretter, Christoph Neukirchen, Georg Rose and Matthias Bertram, Optimal Pre-Filtering for Linear Interpolation in Computed Tomography, Proc. of the 2nd Workshop on High-Performance Image Reconstruction, Beijing, China, September 6, pp. 29–32, 2009. Paper

Colas Schretter, Online PET Reconstruction From List-Mode Data, Proc. of the 10th International Meeting on Fully Three-Dimensional Image Reconstruction in Radiology and Nuclear Medicine, Beijing, China, September 5-10, pp. 195–198, 2009. Paper, Poster

Colas Schretter, Christoph Neukirchen, Georg Rose and Matthias Bertram, Image-Based Iterative Compensation of Motion Artifacts in Computed Tomography, SPIE Medical Imaging, Lake Buena Vista, USA, February 7-12, vol. 7258, pp. 1W–8, 2009. Link

Colas Schretter, Christoph Neukirchen, Georg Rose and Matthias Bertram, Local Correction of Non-Periodic Motion in Computed Tomography, SPIE Medical Imaging, Lake Buena Vista, USA, February 7-12, vol. 7258, pp. 2M–12, 2009. Link, Poster

Colas Schretter, Christoph Neukirchen, Matthias Bertram and Georg Rose, Correction of Some Time-Dependent Deformations in Parallel-Beam Computed Tomography, Proc. of the 5th IEEE International Symposium on Biomedical Imaging, Paris, France, May 14-17, pp. 764–767, 2008. Link

Ralph Brinks, Colas Schretter and Carsten Meyer, Comparison of Maximum-Likelihood List-Mode Reconstruction Algorithms in PET, Proc. of the IEEE Nuclear Science Symposium and Medical Imaging Conference, San Diego, USA, October 29 - November 4, vol. M11-389, pp. 2801–2803, 2006. Link

Colas Schretter, Laurent Gatto and Michel C. Milinkovitch, OligoFaktory: A Web Portal for Interactive Oligonucleotide Design, First BENELUX Bioinformatics Conference, Ghent, Belgium, April 14-15, 2005. Poster