Michael van Ginkel

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—In this paper, we present a stable, recursive algorithm for the Gabor filter that achieves—to within a multiplicative constant—the fastest possible implementation. For a signal consisting of samples, our implementation requires () multiply-and-add (MADD) operations, that is, the number of computations per input sample is constant. Further, the complexity(More)
We measure the sharpness of natural (complex) images using Gaussian models. We first locate lines and edges in the image. We apply Gaussian derivatives at different scales to the lines and edges. This yields a response function, to which we can fit the response function of model lines and edges. We can thus estimate the width and amplitude of the line or(More)
ÐCurved oriented patterns are dominated by high frequencies and exhibit zero gradients on ridges and valleys. Existing curvature estimators fail here. The characterization of curved oriented patterns based on translation invariance lacks an estimation of local curvature and yields a biased curvature-dependent confidence measure. Using parameterized(More)
The generalized Radon (or Hough) transform is a well-known tool for detecting parameterized shapes in an image. The Radon transform is a mapping between the image space and a parameter space. The coordinates of a point in the latter correspond to the parameters of a shape in the image. The amplitude at that point corresponds to the amount of evidence for(More)
The effect of chronological age on skin characteristics is readily visible, and its underlying histological changes have been a field of study for several years. However, the effect of biological age (i.e. a person’s rate of ageing compared to their chronological age) on the skin has so far only been studied in facial photographs. Skin biopsies obtained(More)
Application of an experimental design based on blocking of homogeneous experimental units is an objective approach to reduce experimental error. Often, the experimental design and analysis efforts are considered to be executed satisfactory as long as the coefficient of variation is estimated to be below 10 %, say for yield, as a generally accepted guide for(More)
The generalised Radon transform is a well-known tool for detecting parameterised shapes in an image. Applying the Radon transform to an image results in a parameter response function (PRF). Curves in the image become peaks in the PRF. The location of a peak corresponds to the parameters of a shape, and the amplitude to the amount of evidence for that shape.(More)
The international winter wheat improvement program (IWWIP), an alliance between Turkey–CIMMYT–ICARDA, has distributed improved germplasm to different National Agricultural Research Systems (NARS) partners through international nurseries and yield trials for the last 25 years. This study was carried out in order to determine the rate of breeding progress for(More)
We present a novel approach to parameterised curve detection. The method is based on the generalised Radon transform, which is traditionally applied to a 2D edge/line map. The novelty of our method is the mapping of the original 2D image to a 3D orientation space, which then forms the input for the Radon transform. The orientation space representation can(More)
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