| 1. |
- Lindeberg, Tony, 1964-
(författare)
-
Scale-space for discrete images
- 1989
-
Ingår i: Scandinavian Conference on Image Analysis. ; , s. 1098-1107
-
Konferensbidrag (refereegranskat)abstract
- This article addresses the formulation of a scale-space theory for one-dimensional discrete images. Two main subjects are treated:Which linear transformations remove structure in the sense that the number of local extrema (or zero-crossings) in the output image does not exceed the number of local extrema (or zero-crossings) in the original image?How should one create a multi-resolution family of representations with the property that an image at a coarser level of scale never contains more structure than an image at a finer level of scale?We propose that there is only one reasonable way to define a scale-space for discrete images comprising a continuous scale parameter, namely by (discrete) convolution with the family of kernels T(n; t) = e^{-t} I_n(t),, where $I_n$ are the modified Bessel functions of integer order. Similar arguments applied in the continuous case uniquely lead to the Gaussian kernel.Some obvious discretizations of the continuous scale-space theory are discussed in view of the results presented. An important result is that scale-space violations might occur in the family of representations generated by discrete convolution with the sampled Gaussian kernel.
|
|
| 2. |
|
|
| 3. |
- Lindeberg, Tony, 1964-
(författare)
-
On the Construction of a Scale-Space for Discrete Images
- 1988
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this paper we address the formulation of a scale-space theory for discrete images. We denote a one-dimensional kernel a scale-space kernel if it reduces the number of local extrema and discuss which discrete kernels are possible scale-space kernels. Unimodality and positivity properties are shown to hold for such kernels as well as their Fourier transforms. An explicit expression characterizing all discrete scale-space kernels is given.We propose that there is only one reasonable way to define a scale-space family of images L(x; t) for a one-dimensional discrete signal f(x) namely by convolution with the family of discrete kernels T(n; t) = e^(-t) I_nt(t) where I_n is the modified Bessel function of order n.With this representation, comprising a continuous scale parameter, we are no longer restricted to specific predetermined levels of scale. Further, T(n; t) appears naturally in the solution of a discretized version of the heat equation, both in one and two dimensions.The family T(n; t) (t >= 0) is the only one-parameter family of discrete symmetric shift-invariant kernels satisfying both necessary scale-space requirements and the semigroup property T(n; s) * T(n; t) = T(n; s+t). Similar arguments applied in the continuous case uniquely lead to the family of Gaussian kernels.The commonly adapted technique with a sampled Gaussian produces undesirable effects. It is shown that scale-space violations might occur in the family of functions generated by convolution with the sampled Gaussian kernel. The result exemplifies that properties derived in the continuous case might be violated after discretization.A discussion about the numerical implementation is performed and an algorithm generating the filter coefficients is supplied.
|
|
| 4. |
- Berbyuk, Viktor, 1953, et al.
(författare)
-
Mathematical design of gantry robots for automating assembly processes
- 1989
-
Ingår i: Soviet journal of computer and systems sciences. - 0882-4002. ; 27:2, s. 1-8
-
Tidskriftsartikel (refereegranskat)abstract
- A methodology for an automatic selection of the structural schema and the parameters of an assembly robot based on an optimization procedure is described. A finite collection of so-called test positions for the operating element which are determined by the robot purpose and by its characteristic movements is specified. The dynamic, strength, etc. characteristics are computed at these test positions for each structural schema and the constraints for the optimization problem are formulated. The procedure for selecting the structural schema of the robot and its technical parameters consists of minimizing some functional for the indicated constraints. An example of computing the parameters of a gantry robot is given.
|
|
| 5. |
- Gustavsson, Jan, et al.
(författare)
-
A submultiplicative function
- 1989
-
Ingår i: Indagationes mathematicae (Proceedings). - : Elsevier BV. - 1385-7258. ; 92:4, s. 435-442
-
Tidskriftsartikel (refereegranskat)
|
|
| 6. |
- Gårding, Jonas, et al.
(författare)
-
CanApp : The Candela Application Library
- 1989
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper describes CanApp, the Candela Application Library. CanApp is a software package for image processing and image analysis. Most of the subroutines in CanApp are available both as stand-alone programs and C subroutines.CanApp currently comprises some 50 programs and 75 subroutines, and these numbers are expected to grow continuously as a result of joint efforts of the members of the CVAP group at the Royal Institute of Technology in Stockholm.CanApp is currently installed and running under UNIX on Sun workstations
|
|
