| 1. |
- Andersson, Mats T., et al.
(författare)
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Controllable 3-D Filters for Low Level Computer Vision
- 1993
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Ingår i: SCIA8. - Linköping, Sweden : Linköping University, Department of Electrical Engineering.
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Konferensbidrag (refereegranskat)abstract
- Three-dimensional data processing is becoming more and more common. Typical operations are for example estimation of optical flow in video sequences and orientation estimation in 3-D MR images. This paper proposes an efficient approach to robust low level feature extraction for 3-D image analysis. In contrast to many earlier algorithms the methods proposed in this paper support the use of relatively complex models at the initial processing steps. The aim of this approach is to provide the means to handle complex events at the initial processing steps and to enable reliable estimates in the presence of noise. A limited basis filter set is proposed which forms a basis on the unit sphere and is related to spherical harmonics. From these basis filters, different types of orientation selective filters are synthesized. An interpolation scheme that provides a rotation as well as a translation of the synthesized filter is presented. The purpose is to obtain a robust and invariant feature extraction at a manageable computational cost.
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| 2. |
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| 3. |
- Nordberg, Klas, et al.
(författare)
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On the Equivariance of the Orientation and the Tensor Field Representation
- 1993
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Ingår i: SCIA8. - Linköping, Sweden : Linköping University, Department of Electrical Engineering. - 8299287200 ; , s. 57-63
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The tensor representation has proven a successful tool as a mean to describe local multi-dimensional orientation. In this respect, the tensor representation is a map from the local orientation to a second order tensor. This paper investigates how variations of the orientation are mapped to variation of the tensor, thereby giving an explicit equivariance relation. The results may be used in order to design tensor based algorithms for extraction of image features defined in terms of local variations of the orientation, e.g. multi-dimensional curvature or circular symmetries. It is assumed that the variation of the local orientation can be described in terms of an orthogonal transformation group. Under this assumption a corresponding orthogonal transformation group, acting on the tensor, is constructed. Several correspondences between the two groups are demonstrated.
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| 4. |
- Wiklund, Johan, et al.
(författare)
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Hierarchical Phase Based Disparity Estimation
- 1992
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Ingår i: Proceedings of 2nd Singapore International Conference on Image Processing. - Linköping, Sweden : Linköping University, Department of Electrical Engineering. - 9789810211820 - 9810211821
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Rapport (övrigt vetenskapligt/konstnärligt)
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| 5. |
- Andersson, Mats, et al.
(författare)
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Controllable 3-D Filters
- 1993
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Ingår i: Proceedings of the SSAB Symposium on Image Analysis.
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Konferensbidrag (refereegranskat)
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| 6. |
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| 7. |
- Andersson, Mats T., et al.
(författare)
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Orientation Estimation in Ambiguous Neighbourhoods
- 1991
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Ingår i: Proceedings of SCIA91.
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Konferensbidrag (refereegranskat)abstract
- This paper describes a new algorithm for local orientation estimation. The proposed algorithm detects and separates interfering events in ambiguous neighbourhoods and produces robust estimates of the two most dominant events. A representation suitable for simultaneous representation of two orientations is introduced. The main purpose of this representation is to make averaging of outputs for neigbourhoods containing two orientations possible. The feature extraction is performed by a set of quadrature filters. A method to obtain a large set of quadrature filter responses from a limited basis filter set is introduced. The estimation of the neighbourhood and the separation of the present events are based upon the quadrature responses in terms of local magnitude and phase. The performance of the algorithm is demonstrated using test images.
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| 8. |
- Borga, Magnus, et al.
(författare)
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A Binary Competition Tree for Reinforcement Learning
- 1994
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A robust, general and computationally simple reinforcement learning system is presented. It uses a channel representation which is robust and continuous. The accumulated knowledge is represented as a reward prediction function in the outer product space of the input- and output channel vectors. Each computational unit generates an output simply by a vector-matrix multiplication and the response can therefore be calculated fast. The response and a prediction of the reward are calculated simultaneously by the same system, which makes TD-methods easy to implement if needed. Several units can cooperate to solve more complicated problems. A dynamic tree structure of linear units is grown in order to divide the knowledge space into a sufficiently number of regions in which the reward function can be properly described. The tree continuously tests split- and prune criteria in order to adapt its size to the complexity of the problem.
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| 10. |
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