My research deals with camera related image processing. It is a challenging topic due to requirements set by mobile platforms and various noise and artifact sources due to the miniature size. What is more, the final picture is rated by a human eye, with individually varying preferences.

During the period 1.7.2007 - 30.6.2008 I was working at TUT/ISP in "Computational imaging concepts and algorithms" project funded by the Academy of Finland.

Doctoral Thesis

S. Alenius, "On noise reduction in iterative image reconstruction algorithms for emission tomography: Median root prior," Ph.D. dissertation, Tampere University of Technology, Tampere, Oct. 1999. thesis pdf

Collections

S. Alenius and U. Ruotsalainen, "Bayesian image reconstruction for emission tomography based on median root prior," in 1998 Year book of nuclear medicine, A. Gottschalk, I. Zubal, et al., Eds. St. Louis: Mosby Inc., 1998, ch. 13, pp. 416–417, originally published in European Journal of Nuclear Medicine.

Journal Papers (10)

A. Foi, S. Alenius, V. Katkovnik, and K. Egiazarian, "Noise measurement for raw-data of digital imaging sensors by automatic segmentation of nonuniform targets," IEEE Sensors Journal, vol. 7, no. 10, pp. 1456–1461, Oct. 2007.

R. C. Bilcu, M. Trimeche, S. Alenius, and M. Vehviläinen, "Regularized iterative image restoration in the blur space," WSEAS Transactions on Communications, 2005.

V. Bettinardi, S. Alenius, P. Numminen, M. Teräs, M. Gilardi, F. Fazio, and U. Ruotsalainen,"Implementation and evaluation of an ordered subsets reconstruction algorithm for transmission PET studies using median root prior and inter-update median filtering," European Journal of Nuclear Medicine, vol. 30, no. 2, pp. 222–231, 2003.

S. Alenius and U. Ruotsalainen, "Generalization of median root prior reconstruction," IEEE Transactions on Medical Imaging, vol. 21, no. 11, pp. 1413– 1420, Nov. 2002.

V. Bettinardi, E. Pagani, M. Gilardi, S. Alenius, K. Thielemans, M. Teräs, and F. Fazio, "Implementation and evaluation of a 3D one-step late reconstruction algorithm for 3D positron emission tomography brain studies using median root prior," European Journal of Nuclear Medicine, vol. 29, no. 1, pp. 7–18, 2002.

T. Kauppinen, M. O. Koskinen, S. Alenius, E. Vanninen, and J. T. Kuikka, "Improvement of brain perfusion SPET using iterative reconstruction with scatter and non-uniform attenuation correction," European Journal of Nuclear Medicine, vol. 27, no. 9, pp. 1380–1386, Sept. 2000.

S. Alenius, U. Ruotsalainen, and J. Astola, "Attenuation correction for PET using count-limited transmission images reconstructed with median root prior," IEEE Transactions on Nuclear Science, vol. 46, no. 3, pp. 646–651, June 1999.

C. Katoh, U. Ruotsalainen, H. Laine, S. Alenius, H. Iida, P. Nuutila, and J. Knuuti, "Iterative reconstruction based on median root prior in quantification of myocardial blood flow and oxygen metabolism," Journal of Nuclear Medicine, vol. 40, no. 5, pp. 862–867, 1999.

S. Alenius, U. Ruotsalainen, and J. Astola, "Using local median as the location of the prior distribution in iterative emission tomography image reconstruction," IEEE Transactions on Nuclear Science, vol. 45, no. 6, pp. 3097–3104, Dec. 1998.

S. Alenius and U. Ruotsalainen, "Bayesian image reconstruction for emission tomography based on median root prior," European Journal of Nuclear Medicine, vol. 24, no. 3, pp. 258–265, Mar. 1997.

Conference Papers (25)

R. Bilcu, S. Alenius, and M. Vehviläinen, "Combined de-noising and sharpening of color images in DCT domain", 16th Conference on Digital Signal Processing (DSP2009), July 2009, Santorini.

S. Alenius and R. Bilcu, "Combination of multiple images for flash relightning, " 3rd International Symposium on Communications, Control and Signal Processing (ISCCSP 2008), 2008.

Dmitriy Paliy, Mejdi Trimeche, Vladimir Katkovnik, and Sakari Alenius, "Demosaicing of noisy data: Spatially adaptive approach," SPIE Electronic Imaging, 2007.

Alessandro Foi, Sakari Alenius, Mejdi Trimeche, and Vladimir Katkovnik, "Adaptive-size block transforms for poissonian image deblurring," SMMSP2006, Florence, Italy, September 2006.

Dmitriy Paliy, Vladimir Katkovnik, Sakari Alenius, and Markku Vehviläinen, "Adaptive neighborhood interpolation of noisy images on quincunx grid,"" SMMSP2006, Florence, Italy, September 2006.

M. Tico, S. Alenius, and M. Vehviläinen, "Method of motion estimation for image stabilization," in ICASSP ’06, May 14-19 2006.

R. Bilcu, M. Trimeche, S. Alenius, and M. Vehviläinen, "Blur space iterative de-blurring," in WSEAS/CSCC’05, Athens, Greece, 11.-16.7. 2005.

A. Foi, S. Alenius, M. Trimeche, V. Katkovnik, and K. Egiazarian, "A spatially adaptive poissonian image deblurring," in ICIP’05, Genova, Italy, 11.- 14.9. 2005.

A. P. Happonen and S. Alenius, "A comparison of sinogram and stackgram domain filtering methods employing l-filters for noise reduction of tomographic data," in Proceedings of the 2005 Finnish Signal Processing Symposium, Kuopio, Finland, August 25 2005, pp. 1–4.

A. Happonen and S. Alenius, "Sinogram filtering using a stackgram domain," in 2nd IASTED International Conference: Visualization, Imaging and Image Processing (VIIP 2002), 9-12 Sept. 2002, pp. 339–343.

U. Ruotsalainen, J. Mykkänen, J. Luoma, J. Tohka, and S. Alenius, "Methods to improve repeatability in quantification of brain PET images," in World Congress on Neuroinformatics: Part II Proceedings, ser. ARGESIM Report no. 20. Vienna: ARGESIM/ASIM-Verlag, Sept. 24-29 2001, pp. 659–664.

S. Alenius and U. Ruotsalainen, "Improving the visual quality of median root prior images in PET and SPECT reconstruction," in 2000 IEEE Nuclear Science Symposium, Conference Record, 2001, pp. 15/216 – 15/219.

V. Bettinardi, E. Pagani, S. Alenius, M. Teräs, M.C. Gilard, C. Labbe, M. Jacobson, K. Thielemans, M. Sadki, C. Morel, R. Levkovitz, A. Ben-Tal, T. Spinks, G. Mitra, and F. Fazio, "Implementation and evaluation of a 3D ordered subsets expectation maximization and median root prior (3D OSEM-MRP) reconstruction algorithm," in 2000 IEEE Nuclear Science Symposium, Conference Record, 2001, pp. 15/203–15/206.

T. Kauppinen, S. Alenius, M. Koskinen, and J. Kuikka, "Improvement of SPET using iterative reconstruction and non-uniform attenuation correction," Radioactive Isotopes in Clinical Medicine and Research, 24th International Symposium, Badgastein, Austria, Jan 11-14, 2000, European Journal of Nuclear Medicine (suppl), abstract, vol. 27, no. 1, p. S89, Jan. 2000.

S. Alenius, "Iterative reconstruction with median root prior," in Proceedings of the 8th Symposium on the Medical Application of Cyclotrons, ser. Annales Universitatis Turkuensis, D 346, Turku, Finland, May 22-25 1999, p. 14, invited speech.

T. Kauppinen, S. Alenius, M. Koskinen, and J. Kuikka, "A comparison of two iterative reconstruction methods with non-uniform attenuation correction," Proceedings of the 46th Annual Meeting (Los Angeles, California, USA, June 6-10, 1999.), the Society of Nuclear Medicine, Journal of Nuclear Medicine (suppl), vol. 40, no. 5, p. 301, May 1999.

U. Ruotsalainen, P. Numminen, T. Tolvanen, E. Sutinen, and S. Alenius, "New method for attenuation correction in whole-body PET studies with MRP reconstruction," Proceedings of the 46th Annual Meeting (Los Angeles, California, USA, June 6-10, 1999.), the Society of Nuclear Medicine, Journal of Nuclear Medicine (suppl), vol. 40, no. 5, p. 303, May 1999.

S. Alenius, U. Ruotsalainen, and J. Astola, "Transmission images and attenuation correction with short acquisitions using median root prior reconstruction in PET," in 1998 IEEE Medical Imaging Conference, Conference Record, 1999, pp. 1711–1715.

T. Kauppinen, S. Alenius, V. Turjanmaa, J. Kuikka, and M. Koskinen, "Comparison between iterative median root prior algorithm and filtered back-projection in SPET," European Journal of Nuclear Medicine, vol. 25, no. 8, p. 948, 1998, European Association of Nuclear Medicine (EANM) 1998 abstract.

C. Katoh, U. Ruotsalainen, H. Laine, S. Alenius, H. Iida, P. Nuutila, and J. Knuuti, "A new iterative reconstruction method based on median root prior in quantification of myocardial blood flow and oxygen metabolism with PET," European Journal of Nuclear Medicine, vol. 25, no. 8, p. 991, 1998, European Association of Nuclear Medicine (EANM) 1998 abstract.

S. Alenius, U. Ruotsalainen, and J. Astola, "Using local median as the location of the prior distribution in iterative emission tomography image reconstruction," in 1997 IEEE Medical Imaging Conference, Conference Record, 1998, pp. 1726–1730.

M. Kähkönen, S. Alenius, V. Oikonen, and U. Ruotsalainen, "Improved quantitative images produced by sinogram Patlak and a new iterative reconstruction method," Proceedings of the 44th Annual Meeting (San Antonio, USA, June 1-5, 1997), the Society of Nuclear Medicine, Journal of Nuclear Medicine (suppl), vol. 38, no. 5, p. 196, 1997.

S. Alenius and U. Ruotsalainen, "Bayesian image reconstruction in positron emission tomography using median root prior," in Proceedings of the 7th Symposium on the Medical Application of Cyclotrons, ser. Annales Universitatis Turkuensis, D 185, May 22-25 1995, pp. I 01 – I 02.

S. Alenius, "Bayesian image reconstruction in positron emission tomography using median root prior," in The Proceedings of the First TUT Symposium on Signal Processing, Tampere, Finland, May 20 1994, pp. 113–116.

J. Neejärvi, V. Fischer, S. Alenius, and Y. Neuvo, "Knowledge-based segmentation using morphological filters," in Euromicro ‘91, 17th Symposium on Microprocessing and Microprogramming, Vienna, Austria, September 2-5 1991, pp. 447–452.

Invited Presentations

S. Alenius, "Reconstruction from projections," At TUT/RGI course 7103100 Medical Imaging Methods, 5.2. 2003. (NOTE: pdf attached: tomoRGI.pdf)

S. Alenius, "Reconstruction in positron emission tomography," TICSP/DMI Meeting on Cells and Signals, Tampere, Finland, August 27 1998.

S. Alenius, "Image reconstruction - an example case," in Preconference Tutorial Courses in Biomedical Engineering: Biomedical Signal Processing I, ser. Report No. 2/1996 vol. 10, P. Kauppinen, R. Lehtinen, and J. Malmivuo, Eds. Tampere University of Technology, Ragnar Granit Institute, 1996, pp. 171–181.