Colas Schretter

I am a computer scientist, developing new statistical algorithms for image reconstruction and rendering.

Keywords

Physically-based modeling, Monte-Carlo simulations, geometric algorithms, density estimation, expectation-maximization, image formation, tomography, C++, STL, demomaking, skateboarding, cooking & eating, …

Contact

My [resume] contains current contact information.

Bio

I received my M.Sc. degree in computer science with great honors from the Université libre de Bruxelles, Belgium. From November 2003, I developed interactive bioinformatic softwares at Milinkovitch's lab then worked on an image reconstruction project with Michel Defrise and Serge Goldman. I moved to Germany in February 2007 for a scientist position with Philips Research, Aachen. Meanwhile, I was granted an European Marie Curie fellowship for my doctoral thesis, endorsed with magna cum laude by the Otto-von-Guericke University, Magdeburg. Since May 2010, I'm postdoctoral researcher with the group of Leif Kobbelt at the RWTH Aachen University. From October 2011, I will be visiting the DEI at Politecnico di Milano, in Italy.

Interests

My recent work combines emergent machine learning techniques with classical geometrical algorithms for solving large density estimation problems with multi-resolution (scale-space) semi-parametric Gaussian mixture models. In particular, I'm developing novel online expectation-maximization methods for statistical image reconstruction in time-of-flight positron emission tomography (TOF-PET) and for fast evaluations of smoothed visibility queries in computer rendering with image-based lighting. This project is sponsored by the Framework Programme 7 of the European Commission under contract PERG06-GA-2009-256519.

Links

Journal papers

Colas Schretter, Paul-Olivier Dehaye and Leif Kobbelt, Golden Ratio Sequences for Low-Discrepancy Sampling, Journal of Graphics Tools, in press, 2011.

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]

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]

Poster presentations

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, 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, 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]

Alfonso A. Isola, Colas Schretter, Michael Grass, Matthias Bertram, Georg Rose and Wiro J. Niessen, Compensation of Periodic Cardiac Motion and Non-Periodic Abdominal Motion in Cone-Beam CT, Marie Curie Monitoring Mission, Alexander von Humboldt Foundation, Bonn, Germany, January 29-30, 2009. [poster]

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.

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, Oct. 29-Nov. 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]

Conference lectures

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]

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

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

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]

Technical notes

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, Computing Random Points on Sphere, Boost C++ Ticket 1059, June, 2007. [link]

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

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

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.

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]

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