Hans Jakob Rivertz
+4773559009
218 IT-bygget, sydfløy Gløshaugen, Trondheim
About
Hans Jakob Rivertz is an Associate Professor at the Department of Computer Science (IDI), Faculty of Information Technology and Electrical Engineering at NTNU. He has an interdisciplinary background that combines computer science and mathematics.
Academic Background and Early Career
His earliest publication was in 1996 with the paper “Stability of geodesic spheres”, which deals with the stability of soap bubbles in two-point homogeneous spaces. He later earned a PhD in differential geometry, with a dissertation on isometric immersions. A key result from his thesis is an invariant that is both necessary and sufficient for the existence of isometric immersions. Rivertz' supervisor was Per Tomter a student of Stephen Smale.
In the early 2000s, he participated in several projects at the Norwegian Computing Center (Norsk Regnesentral), including the development of technical reports on the JPEG 2000 codec, Channel-S streaming, and privacy and security in mobile-based systems.
Starting in 2004, his research expanded to include aperiodic tilings, with publications such as “Self-similar symmetric planar tilings” and “Self-similar aperiodic patterns with 9-fold symmetry.”
Since 2009, he has had a close research collaboration with Ali Alsam, working on image enhancement, color science, and numerical methods. Notable publications from this collaboration include Algebraic Colour to Grayscale (2012), Color Edge Preserving Smoothing (2013), and Improved Color Edge Preserving Smoothing (2019).
His more recent work covers color spaces, metamers, and combinatorics, including “Multiset permutation generation by transpositions” (2024) and “Anisotropic Diffusion in Riemannian Colour Geometry” (2025).
Software Development and Project Leadership
He has developed research tools and educational applications such as SciPrompter (a teleprompter with support for mathematical formulas) and FraxPlorer (an interactive Mandelbrot explorer), available at rivertz.folk.ntnu.no. His supervision encourages interdisciplinary student projects in modeling, algorithm design, and visual mathematics.
Competencies
Publications
2024
-
Farup, Ivar;
Rivertz, Hans.
(2024)
Anisotropic Diffusion in Riemannian Colour Geometry.
Journal of Mathematical Imaging and Vision
Academic article
2023
-
Rivertz, Hans.
(2023)
Multiset permutation generation by transpositions.
arXiv.org
Academic article
-
Rivertz, Hans;
Mackiewicz, Michal.
(2023)
Optimised Spherical Sampling of the Object Colour Solid.
The Society for Imaging Science and Technology
Academic chapter/article/Conference paper
2022
-
Alsam, Ali;
Rivertz, Hans Jakob.
(2022)
Three dimensional surface preserving smoothing.
The Society for Imaging Science and Technology
Academic chapter/article/Conference paper
2021
-
Alsam, Ali;
Rivertz, Hans.
(2021)
Long range diffusion with control of the directional differences.
The Society for Imaging Science and Technology
Academic chapter/article/Conference paper
2020
-
Rivertz, Hans Jakob.
(2020)
On filters making an imaging sensor more colorimetric.
The Society for Imaging Science and Technology
Academic chapter/article/Conference paper
2019
-
Mackiewicz, Michal;
Rivertz, Hans Jakob;
Finlayson, Graham.
(2019)
Spherical sampling methods for the calculation of metamer mismatch volumes.
Optical Society of America. Journal A: Optics, Image Science, and Vision (JOSA A)
Academic article
-
Rivertz, Hans Jakob;
Alsam, Ali.
(2019)
Colour to Grey by Maximum Signed Gradient.
IEEE conference proceedings
Academic chapter/article/Conference paper
-
Alsam, Ali;
Rivertz, Hans Jakob.
(2019)
Improved color edge preserving smoothing.
NIKT: Norsk IKT-konferanse for forskning og utdanning
Academic article
-
Rivertz, Hans Jakob.
(2019)
On an Euler-Lagrange equation for color to grayscale conversion.
The Society for Imaging Science and Technology
Academic chapter/article/Conference paper
2018
-
Alsam, Ali;
Rivertz, Hans Jakob.
(2018)
A mathematical approach to best luminance maps.
Optical Society of America. Journal A: Optics, Image Science, and Vision (JOSA A)
Academic article
2017
-
Mackiewicz, Michal;
Rivertz, Hans Jakob;
Finlayson, Graham.
(2017)
Metamer Mismatch Volumes Using Spherical Sampling.
The Society for Imaging Science and Technology
Academic chapter/article/Conference paper
-
Eschenburg, Jost-Hinrich;
Rivertz, Hans Jakob.
(2017)
The complete cartwheel tiling.
Journal of Geometry
Academic article
2015
-
Alsam, Ali;
Rivertz, Hans Jakob.
(2015)
Fast scale space image decomposition.
IEEE conference proceedings
Academic chapter/article/Conference paper
-
Alsam, Ali;
Farup, Ivar;
Rivertz, Hans Jakob.
(2015)
Iterative sharpening for image contrast enhancement.
IEEE conference proceedings
Academic chapter/article/Conference paper
-
Rivertz, Hans Jakob.
(2015)
Self-similar aperiodic patterns with 9-fold symmetry.
Journal of Number Theory
Academic article
2014
-
Rivertz, Hans Jakob;
Alsam, Ali.
(2014)
Drawing Parrots with Charcoal.
Springer
Academic chapter/article/Conference paper
-
Eschenburg, Jost-Hinrich;
Rivertz, Hans Jakob.
(2014)
Self similarity of dihedral tilings.
Journal of Algebra
Academic article
2013
-
Alsam, Ali;
Rivertz, Hans Jakob.
(2013)
Color Edge Preserving Smoothing.
Springer
Academic chapter/article/Conference paper
-
Rivertz, Hans Jakob.
(2013)
On real local isometric immersions of CQ^2_c into CP^3.
Journal of Geometry
Academic article
-
Alsam, Ali;
Rivertz, Hans Jakob;
Sharma, Puneet.
(2013)
What the eye did not see--a fusion approach to image coding.
International journal on artificial intelligence tools
Academic article
-
Rivertz, Hans Jakob.
(2013)
On those ordinary differential equations that are solved exactly by the improved Euler method.
Archivum Mathematicum
Academic article
2012
-
Alsam, Ali;
Rivertz, Hans Jakob.
(2012)
Algebraic color to grayscale.
ACTA Press
Academic chapter/article/Conference paper
-
Alsam, Ali;
Rivertz, Hans Jakob;
Sharma, Puneet.
(2012)
What the Eye Did Not See – A Fusion Approach to Image Coding.
Springer
Academic chapter/article/Conference paper
-
Røe, Per;
Arnesen, Ragni Ryvold;
Danielsson, Jerker;
Vestgården, Jørn Inge;
Rivertz, Hans Jakob;
Boudko, Svetlana.
(2012)
TrueGen 4.0 Design.
NR-notat (DART/11/2012)
Report
2011
-
Alsam, Ali;
Rivertz, Hans Jakob.
(2011)
Fast Edge Preserving Smoothing Algorithm.
ACTA Press
Academic chapter/article/Conference paper
-
Alsam, Ali;
Rivertz, Hans Jakob.
(2011)
Constrained Gradient Integration for Improved Image Contrast.
ACTA Press
Academic chapter/article/Conference paper
-
Rivertz, Hans Jakob.
(2011)
On local isometric immersions into complex and quaternionic projective spaces.
Archivum Mathematicum
Academic article
2009
-
Rivertz, Hans Jakob.
(2009)
On an invariant on isometric immersions into spaces of constant sectional curvature.
Ukrainian Mathematical Journal
Academic article
2007
-
Rivertz, Hans Jakob;
Eschenburg, Jost-Hinrich.
(2007)
Self similar symmetric planar tilings.
Journal of Geometry
Academic article
2005
-
Østvold, Bjarte M.;
Rivertz, Hans Jakob.
(2005)
Performance evaluation of the Velocity Database Engine.
Report
-
Rivertz, Hans Jakob.
(2005)
Bluetooth security.
Report
-
Danielsson, Jerker;
Groven, Arne-Kristian;
Kristoffersen, Thor;
Rivertz, Hans Jakob;
Skomedal, Åsmund.
(2005)
Elektroniske spor.
Report
2004
-
Boudko, Svetlana;
Rivertz, Hans Jakob.
(2004)
The NR JPEG 2000-codec.
NR-notat (DART/08/04)
Report
-
Kristoffersen, Thor;
Vestgården, Jørn Inge;
Rivertz, Hans Jakob.
(2004)
Design and Implementation of the Channel-S Streaming System.
NR-notat (DART/07/04)
Report
2003
-
Aredo, Demissie;
Rivertz, Hans Jakob;
Vestgården, Jørn Inge.
(2003)
LBS System Architecture with Privacy.
Ukjent
Academic article
2002
-
Arnesen, Ragni Ryvold;
Huseby, Ragnar Bang;
Rivertz, Hans Jakob;
Røe, Per;
Snekkenes, Einar;
Vestgården, Jørn Inge.
(2002)
Replacement of random number generator in Norsk Tipping's random number draw system.
NR-notat (GEM/02/02)
Report
2001
-
Arnesen, Ragni Ryvold;
Aredo, Demissie;
Huseby, Ragnar Bang;
Rivertz, Hans Jakob;
Rue, Håvard;
Snekkenes, Einar.
(2001)
Random Number Draw System - Design.
Norsk Regnesentral
Report
1996
-
Rivertz, Hans Jakob;
Tomter, Per.
(1996)
Stability of geodesic spheres.
World Scientific
Academic chapter/article/Conference paper
Journal publications
-
Farup, Ivar;
Rivertz, Hans.
(2024)
Anisotropic Diffusion in Riemannian Colour Geometry.
Journal of Mathematical Imaging and Vision
Academic article
-
Rivertz, Hans.
(2023)
Multiset permutation generation by transpositions.
arXiv.org
Academic article
-
Mackiewicz, Michal;
Rivertz, Hans Jakob;
Finlayson, Graham.
(2019)
Spherical sampling methods for the calculation of metamer mismatch volumes.
Optical Society of America. Journal A: Optics, Image Science, and Vision (JOSA A)
Academic article
-
Alsam, Ali;
Rivertz, Hans Jakob.
(2019)
Improved color edge preserving smoothing.
NIKT: Norsk IKT-konferanse for forskning og utdanning
Academic article
-
Alsam, Ali;
Rivertz, Hans Jakob.
(2018)
A mathematical approach to best luminance maps.
Optical Society of America. Journal A: Optics, Image Science, and Vision (JOSA A)
Academic article
-
Eschenburg, Jost-Hinrich;
Rivertz, Hans Jakob.
(2017)
The complete cartwheel tiling.
Journal of Geometry
Academic article
-
Rivertz, Hans Jakob.
(2015)
Self-similar aperiodic patterns with 9-fold symmetry.
Journal of Number Theory
Academic article
-
Eschenburg, Jost-Hinrich;
Rivertz, Hans Jakob.
(2014)
Self similarity of dihedral tilings.
Journal of Algebra
Academic article
-
Rivertz, Hans Jakob.
(2013)
On real local isometric immersions of CQ^2_c into CP^3.
Journal of Geometry
Academic article
-
Alsam, Ali;
Rivertz, Hans Jakob;
Sharma, Puneet.
(2013)
What the eye did not see--a fusion approach to image coding.
International journal on artificial intelligence tools
Academic article
-
Rivertz, Hans Jakob.
(2013)
On those ordinary differential equations that are solved exactly by the improved Euler method.
Archivum Mathematicum
Academic article
-
Rivertz, Hans Jakob.
(2011)
On local isometric immersions into complex and quaternionic projective spaces.
Archivum Mathematicum
Academic article
-
Rivertz, Hans Jakob.
(2009)
On an invariant on isometric immersions into spaces of constant sectional curvature.
Ukrainian Mathematical Journal
Academic article
-
Rivertz, Hans Jakob;
Eschenburg, Jost-Hinrich.
(2007)
Self similar symmetric planar tilings.
Journal of Geometry
Academic article
-
Aredo, Demissie;
Rivertz, Hans Jakob;
Vestgården, Jørn Inge.
(2003)
LBS System Architecture with Privacy.
Ukjent
Academic article
Part of book/report
-
Rivertz, Hans;
Mackiewicz, Michal.
(2023)
Optimised Spherical Sampling of the Object Colour Solid.
The Society for Imaging Science and Technology
Academic chapter/article/Conference paper
-
Alsam, Ali;
Rivertz, Hans Jakob.
(2022)
Three dimensional surface preserving smoothing.
The Society for Imaging Science and Technology
Academic chapter/article/Conference paper
-
Alsam, Ali;
Rivertz, Hans.
(2021)
Long range diffusion with control of the directional differences.
The Society for Imaging Science and Technology
Academic chapter/article/Conference paper
-
Rivertz, Hans Jakob.
(2020)
On filters making an imaging sensor more colorimetric.
The Society for Imaging Science and Technology
Academic chapter/article/Conference paper
-
Rivertz, Hans Jakob;
Alsam, Ali.
(2019)
Colour to Grey by Maximum Signed Gradient.
IEEE conference proceedings
Academic chapter/article/Conference paper
-
Rivertz, Hans Jakob.
(2019)
On an Euler-Lagrange equation for color to grayscale conversion.
The Society for Imaging Science and Technology
Academic chapter/article/Conference paper
-
Mackiewicz, Michal;
Rivertz, Hans Jakob;
Finlayson, Graham.
(2017)
Metamer Mismatch Volumes Using Spherical Sampling.
The Society for Imaging Science and Technology
Academic chapter/article/Conference paper
-
Alsam, Ali;
Rivertz, Hans Jakob.
(2015)
Fast scale space image decomposition.
IEEE conference proceedings
Academic chapter/article/Conference paper
-
Alsam, Ali;
Farup, Ivar;
Rivertz, Hans Jakob.
(2015)
Iterative sharpening for image contrast enhancement.
IEEE conference proceedings
Academic chapter/article/Conference paper
-
Rivertz, Hans Jakob;
Alsam, Ali.
(2014)
Drawing Parrots with Charcoal.
Springer
Academic chapter/article/Conference paper
-
Alsam, Ali;
Rivertz, Hans Jakob.
(2013)
Color Edge Preserving Smoothing.
Springer
Academic chapter/article/Conference paper
-
Alsam, Ali;
Rivertz, Hans Jakob.
(2012)
Algebraic color to grayscale.
ACTA Press
Academic chapter/article/Conference paper
-
Alsam, Ali;
Rivertz, Hans Jakob;
Sharma, Puneet.
(2012)
What the Eye Did Not See – A Fusion Approach to Image Coding.
Springer
Academic chapter/article/Conference paper
-
Alsam, Ali;
Rivertz, Hans Jakob.
(2011)
Fast Edge Preserving Smoothing Algorithm.
ACTA Press
Academic chapter/article/Conference paper
-
Alsam, Ali;
Rivertz, Hans Jakob.
(2011)
Constrained Gradient Integration for Improved Image Contrast.
ACTA Press
Academic chapter/article/Conference paper
-
Rivertz, Hans Jakob;
Tomter, Per.
(1996)
Stability of geodesic spheres.
World Scientific
Academic chapter/article/Conference paper
Report
-
Røe, Per;
Arnesen, Ragni Ryvold;
Danielsson, Jerker;
Vestgården, Jørn Inge;
Rivertz, Hans Jakob;
Boudko, Svetlana.
(2012)
TrueGen 4.0 Design.
NR-notat (DART/11/2012)
Report
-
Østvold, Bjarte M.;
Rivertz, Hans Jakob.
(2005)
Performance evaluation of the Velocity Database Engine.
Report
-
Rivertz, Hans Jakob.
(2005)
Bluetooth security.
Report
-
Danielsson, Jerker;
Groven, Arne-Kristian;
Kristoffersen, Thor;
Rivertz, Hans Jakob;
Skomedal, Åsmund.
(2005)
Elektroniske spor.
Report
-
Boudko, Svetlana;
Rivertz, Hans Jakob.
(2004)
The NR JPEG 2000-codec.
NR-notat (DART/08/04)
Report
-
Kristoffersen, Thor;
Vestgården, Jørn Inge;
Rivertz, Hans Jakob.
(2004)
Design and Implementation of the Channel-S Streaming System.
NR-notat (DART/07/04)
Report
-
Arnesen, Ragni Ryvold;
Huseby, Ragnar Bang;
Rivertz, Hans Jakob;
Røe, Per;
Snekkenes, Einar;
Vestgården, Jørn Inge.
(2002)
Replacement of random number generator in Norsk Tipping's random number draw system.
NR-notat (GEM/02/02)
Report
-
Arnesen, Ragni Ryvold;
Aredo, Demissie;
Huseby, Ragnar Bang;
Rivertz, Hans Jakob;
Rue, Håvard;
Snekkenes, Einar.
(2001)
Random Number Draw System - Design.
Norsk Regnesentral
Report
Outreach
2016
-
PosterFinlayson, Graham; Mackiewicz, Michal; Rivertz, Hans Jakob. (2016) Computing the object colour solid using spherical sampling. Progress in Colour Studies PICS 2016 , University College London 2016-09-14 - 2016-09-16
2011
-
Academic lectureAlsam, Ali; Rivertz, Hans Jakob. (2011) Constrained gradient integration for improved image contrast. IASTED Signal and Image Processing (SIP 2011) , Dallas 2011-12-14 - 2011-12-16
-
Academic lectureAlsam, Ali; Rivertz, Hans Jakob. (2011) Fast edge preserving smoothing algorithm. IASTED Signal and Image Processing - SIP 2011 , Dallas 2011-12-14 - 2011-12-16