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Jasper van de Gronde

  • room number: 491 (Bernoulliborg, building 5161)
  • e-mail: j.j.van.de.gronde rug.nl

Research interests

I am interested in all sorts of image processing topics, including compressed sensing, linear and morphological filters, and deep learning, with a special interest in applications on large/high-dimensional and non-scalar data. Making proper use of vector- or tensor-valued data, possibly as an intermediate step, also interests me greatly, as does the interplay between (mostly) linear approaches and morphological approaches. My PhD thesis was on morphological operators for tensor images, exploring shape and structure in movement and direction dependence. I defended my thesis on 30 June 2015, and am currently a post-doc.

Tensor images (or volumes) are just like ordinary images or volumes, except that at each point we have a vector or matrix (tensors are essentially a generalization of vectors and matrices). To visualize a tensor image with matrices at each position, we typically use "glyphs": for each position a small glyph is drawn whose shape represents the matrix (S). The glyph is often a unit sphere deformed in such a way that each vector v on the unit sphere is given the magnitude v.(S.v). Below you can interact with a live demonstration of this technique (requires a WebGL capable browser, I recommend Firefox, and possibly some patience):

Rotating
Click and drag.
Zooming
Press +/- or use mousewheel.
Glyph resizing
Hold Ctrl and zoom. Press 'u' to make all glyphs approximately the same size.
Cutting plane
Press 'c'. The plane will be parallel to the screen and through the origin.
In this case, the matrices describe stresses at atomic positions in a nanowire (courtesy of S.S.R. Saane, Micromechanics group, RuG). Blue shows positive values(/radii), while orange shows negative values.

Demos

Apart from the rendering above, here is some more code you can try out both in the browser and using Node.js:

There are also some demos that can only be run off-line:

Various projects not (necessarily) associated with a particular publication can be found on Github (also see the SciJS repository).

Further information and links

I maintain a bibliography of work done on both colour morphology and tensor morphology (note that I'm not too strict about what classifies as "colour" morphology). I try to subclassify (using tags) papers based on what kind of method they use. If you feel anything is missing or wrong, please let me know.

An interesting (informal) discussion of the problem of finding a total order for colours can be found here. Note that most of the approaches discussed there indeed correspond to actual algorithms that have been tried in mathematical morphology (and the overview is even fairly, although not entirely, complete). In particular, people have experimented with methods similar to the Hilbert curve approach (Chanussot1998), as well as the travelling salesman approach (Florez2005, Chevallier2014). But note that Chevallier has shown that any total order is necessarily discontinuous when computing joins and meets (this is part of the reason why much of my thesis is focussed on making partial orders more palatable).

Although I tend to talk about product orders and lexicographical orders, there are many more related concepts, as well as different terms for the same concepts. To clarify, I have made a short summary of different terms and in which context they are used.

Publications

Venustiano Soancatl Aguilar, Jasper J. van de Gronde, Claudine J. C. Lamoth, Mike van Diest, Natasha M. Maurits, and Jos B. T. M. Roerdink. Visual Data Exploration for Balance Quantification in Real-Time During Exergaming. PLOS ONE, 12(1):e0170906, January 2017.   doi
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Herman Schubert, Jasper J. van de Gronde, and Jos B. T. M. Roerdink. Efficient Computation of Greyscale Path Openings. Mathematical Morphology - Theory and Applications, 1(1):189–202, 2016.   doi
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Jasper J. van de Gronde, André R. Offringa, and Jos B. T. M. Roerdink. Efficient and Robust Path Openings using the Scale-Invariant Rank Operator. Journal of Mathematical Imaging and Vision, 56(3):455–471, 2016.   doi
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Jasper J. van de Gronde and Jos B. T. M. Roerdink. Generalized Morphology using Sponges. Mathematical Morphology - Theory and Applications, 1(1):18–41, 2016.   doi
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Chengtao Ji, Jasper J. and Maurits van de Gronde, and Jos B. T. M. Roerdink. Tracking and Visualizing Dynamic Structures in Multichannel EEG Coherence Networks. In EuroVis 2016 - Posters. The Eurographics Association, pages 28–30, 2016.   doi
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Venustiano Soancatl, Jasper J. van de Gronde, Natasha M. Maurits, Claudine C. J. C. Lamoth, and Jos B. T. M. Roerdink. Curvature and Speed for Balance Quantification During Exergaming. In Proceedings of the 9th International Conference on Motion in Games. New York, NY, USA. ACM, pages 201–202, 2016.   doi
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Venustiano Soancatl, J. J. and Lamoth van de Gronde, N. M. Maurits, and Roerdink, Jos B. T. M.. Visual Data Exploration for Balance Quantification During Exergaming. In EuroVis 2016 - Posters. Groningen. The Eurographics Association, pages 25–27, 2016.   doi
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Jasper J. van de Gronde and Jos B. T. M. Roerdink. Sponges for Generalized Morphology. In J\’on Atli Benediktsson, Jocelyn Chanussot, Laurent Najman, and Hugues Talbot, eds., Mathematical Morphology and Its Applications to Signal and Image Processing. Springer International Publishing, pages 351–362, 2015.   doi
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Jasper J. van de Gronde. Tensorial Orientation Scores. In Computer Analysis of Images and Patterns. Springer International Publishing, pages 783–794, 2015.   doi
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Jasper J. van de Gronde. Beyond Scalar Morphology. PhD thesis, University of Groningen, 2015.   url
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Jasper J. van de Gronde, Herman R. Schubert, and Jos B. T. M. Roerdink. Fast Computation of Greyscale Path Openings. In J\’on Atli Benediktsson, Jocelyn Chanussot, Laurent Najman, and Hugues Talbot, eds., Mathematical Morphology and Its Applications to Signal and Image Processing. Springer International Publishing, pages 621–632, 2015.   doi
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Jasper J. van de Gronde, Mikola Lysenko, and Jos B. T. M. Roerdink. Path-Based Mathematical Morphology on Tensor Fields. In Ingrid Hotz and Thomas Schultz, eds., Visualization and Processing of Higher Order Descriptors for Multi-Valued Data. Springer International Publishing, pages 109–127, 2015.   doi
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Jasper J. van de Gronde and Jos B. T. M. Roerdink. Group-Invariant Colour Morphology Based on Frames. IEEE Transactions on Image Processing, 23(3):1276–1288, March 2014.   doi
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Jasper J. van de Gronde and Jos B. T. M. Roerdink. Frames, the Loewner order and eigendecomposition for morphological operators on tensor fields. Pattern Recognition Letters, 47:40–49, 2014.   doi
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Jasper J. van de Gronde and Jos B. T. M. Roerdink. Group-Invariant Frames for Colour Morphology. In Cris L. Luengo Hendriks, Gunilla Borgefors, and Robin Strand, eds., Mathematical Morphology and Its Applications to Signal and Image Processing. Springer Berlin Heidelberg, pages 267–278, 2013.   doi
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Jasper J. van de Gronde and Jos B. T. M. Roerdink. Frames for Tensor Field Morphology. In Frank Nielsen and Frédéric Barbaresco, eds., Geometric Science of Information. Springer Berlin Heidelberg, pages 527–534, 2013.   doi
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Jasper J. van de Gronde. Web Graphics for Science. In HTML5 Developer Conference. October, October 2013.   url
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Jasper J. van de Gronde, Michael H. F. Wilkinson, and Jos B. T. M. Roerdink. Rotation-invariant morphological filtering of tensor fields using frames. In Poster session of the National ICT.OPEN (Eindhoven). November, November 2013.   pdf
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Jasper J. van de Gronde and Jos B. T. M. Roerdink. Group-Invariant Frames for Colour Morphology. In ASCI.OPEN (Eindhoven). November, November 2013.   bib
A. R. Offringa and J. J. van de Gronde and J. B. T. M. Roerdink. A morphological algorithm for improving radio-frequency interference detection. Astronomy & Astrophysics, 539(A95), March 2012.   doi
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Jasper J. van de Gronde, Michael H.F. Wilkinson, and Jos B.T.M. Roerdink. Making computers see tensors using mathematical morphology. In Poster session of the National ICT.OPEN (Rotterdam). October, October 2012.   pdf
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Jasper van de Gronde. A High Quality Solver for Diffusion Curves. Master’s thesis, University of Groningen, December 2010.   pdf
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