Peter Johansen

Professor, Dr. Phil.

Phone: +45 35 32 14 42 (local University calls, use 2 14 42)
Fax: +45 35 32 14 01
DIKU room S203

Peter Johansen was born 1938 and became mag.scient. in Mathematics from the University of Copenhagen in 1962. From 1962 to 1964 he served his civil service. From 1964 to 1967 he was amanuensis at the laboratory for Pulse- and Digital Techniques at the Technical University at Lyngby, Denmark. From 1967 to 1969 he was a research staff member at MIT, USA. In 1973 he became dr. phil. at the University of Copenhagen. From 1977 to 1978 he was a visiting professor at the University of Manoa, Hawaii, USA.

He was chairman for the program committee of the Scandinavian Conferences on Image Analysis (SCIA) in 1983 and 1991. He was chairman of the "11th Scandinavian Conference on Image Analysis" in 1999, and on the programme board of "Second International Conference on Scale-Space Theories in Computer Vision" in 1999. He was chairman of the Danish Conferences for Pattern Recognition and Pattern Analysis from 1993-1999. Chairman of the European Conference on Computer Vision in Copenhagen 2002. He is on the board of directors of the Copenhagen Image and Signal Processing Graduate School. Program Committee of the International Conference for Scale Space 2003 and of The Scandinavian Conference on Image Analysis 2003.

1981-1983 he was a member of the Danish Natural Science Council. In 1984 he became a member of the Royal Danish Academy of Sciences and Letters. 1988-1990 he was Dean of the Faculty of Natural Science at the University of Copenhagen. He has been a consultant for NUTEK, the institute for technogical development in Sweden and for the Swedish Foundation for Strategic Research. He is a member of the board of Danish Pattern Recognition Society and he is presently chairman of "Dansk Selskab for Datalogi". Peter Johansens professional interest is computational vision, in particular algebraic and combinatorial aspects.

Research Program

Recent work on image warping is reported in

  • Products of random matrices
    A.D. Jackson, B. Lautrup, P. Johansen, and M. Nielsen,
    Physical Review E, volume 66, nr 6, 2002
  • Brownian Warps: A least committed prior for non-rigid registration
    M. Nielsen, P. Johansen, A. D. Jackson, and B. Lautrup,
    MICCAI 2002, Lecture Notes in Computer Science, Volume 2489, pages 557-564

    Assigning semantics to data by computing compact representations seems to be a promising approach. ``A short description is a good description''. Inspired by Kolmogorov complexity and by Jorma Rissanen's work on Minimum description length (MDL), I use Lempel and Ziv's compression ideas on image sequences:

  • Adaptive pattern recognition
    Peter Johansen,
    Journal of Mathematical Imaging and Vision, Volume 7, pages 325-339, 1997
  • Proposal for a solution to the surveillence problem,
    Peter Johansen,
    In Proceedings of the 8th Scandinavian Conference on Image Analysis, Tromsø, Norway, May 1993.

    Viewing a learning system as a non-linear dynamical system, it seems attractive to model learning behaviors as stable attractors. I have made initial computational experiments with a Lempel-Ziv-type prediction algorithm:

  • On-line string matching with feedback,
    Peter Johansen,
    Theoretical Computer Science, pages 53-67, April 1995.

    Efforts to describe the representation of images by their scale-space properties are reported in

  • Branch Points in One-dimensional Gaussian Scale Space,
    Peter Johansen, Mads Nielsen, and Ole Fogh Olsen,
    Journal of Mathematical Imaging and Vision 13(3): 193-203; Dec 2000
  • Classification of toppoints for the gradient squared,
    Ole Fogh Olsen and Peter Johansen,
    Technical Report 97/24, Department of Computer Science, University of Copenhagen, Denmark
  • Local Analysis of Scale Space,
    Peter Johansen,
    Technical Report 97/2, Department of Computer Science, University of Copenhagen, Denmark.
  • On the classification of toppoints in scale space,
    Peter Johansen,
    Journal of Mathematical Imaging and Vision, 4:57-67, 1994.
  • Representing signals by their toppoints in scale space,
    Peter Johansen, Stig Skelboe, Klaus Grue, and Jens Damgaard Andersen,
    In Proceedings of the International Conference on Image Analysis and Pattern Recognition, 1986.

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