| 1. |
- Curic, Vladimir, et al.
(författare)
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Salience adaptive structuring elements
- 2012
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Ingår i: IEEE Journal on Selected Topics in Signal Processing. - 1932-4553 .- 1941-0484. ; 6:7, s. 809-819
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Tidskriftsartikel (refereegranskat)abstract
- Spatially adaptive structuring elements adjust their shape to the local structures in the image, and are often defined by a ball in a geodesic distance or gray-weighted distance metric space. This paper introduces salience adaptive structuring elements as spatially variant structuring elements that modify not only their shape, but also their size according to the salience of the edges in the image. Morphological operators with salience adaptive structuring elements shift edges with high salience to a less extent than those with low salience. Salience adaptive structuring elements are less flexible than morphological amoebas and their shape is less affected by noise in the image. Consequently, morphological operators using salience adaptive structuring elements have better properties.
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| 2. |
- Curic, Vladimir, et al.
(författare)
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Salience-Based Parabolic Structuring Functions
- 2013
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Ingår i: Mathematical Morphology and Its Applications to Signal and Image Processing. - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 9783642382932 ; 7883, s. 183-194
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Konferensbidrag (refereegranskat)abstract
- It has been shown that the use of the salience map based on the salience distance transform can be useful for the construction of spatially adaptive structuring elements. In this paper, we propose salience-based parabolic structuring functions that are defined for a fixed, predefined spatial support, and have low computational complexity. In addition, we discuss how to properly define adjunct morphological operators using the new spatially adaptive structuring functions. It is also possible to obtain flat adaptive structuring elements by thresholding the salience-based parabolic structuring functions.
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| 3. |
- Luengo, Cris, et al.
(författare)
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Adaptive structuring elements based on salience information
- 2012
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Ingår i: Lecture Notes in Computer Science. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 0302-9743 .- 1611-3349. ; 7594, s. 321-328, s. 321-328
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Konferensbidrag (refereegranskat)abstract
- Adaptive structuring elements modify their shape and size according to the image content and may outperform fixed structuring elements. Without any restrictions, they suffer from a high computational complexity, which is often higher than linear with respect to the number of pixels in the image. This paper introduces adaptive structuring elements that have predefined shape, but where the size is adjusted to the local image structures. The size of adaptive structuring elements is determined by the salience map that corresponds to the salience of the edges in the image, which can be computed in linear time. We illustrate the difference between the new adaptive structuring elements and morphological amoebas. As an example of its usefulness, we show how the new adaptive morphological operations can isolate the text in historical documents.
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| 4. |
- Barrera, Tony, et al.
(författare)
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Vectorized table driven algorithms for double precision elementary functions using Taylor expansions
- 2009
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Ingår i: APLIMAT 8th international conference. ; 2, s. 171-178
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Konferensbidrag (refereegranskat)abstract
- This paper presents fast implementations of the inverse square root and arcsine, both in double precision. In single precision it is often possible to use a small table and one ordinary Newton-Raphson iteration to compute elementary functions such as the square root. In double precision a substantially larger table is necessary to obtain the desired precision, or, if a smaller table is used, the additional Newton-Raphson iterations required to obtain the precision often requires the evaluation of other expensive elementary functions. Furthermore, large tables use a lot of the cash memory that should have been used for the application code.Obtaining the desired precision using a small table can instead be realised by using a higher order method than the second order Newton-Raphson method. A generalization of Newton's method to higher order is Householder's method, which unfortunately often results in very complicated expressions requiring many multiplications, additions, and even divisions.We show how a high-order method can be used, which only requires a few extra additions and multiplications for each degree of higher order. The method starts from the Taylor expansion of the difference of the value of the elementary function and a starting guess value for each iteration. If the Taylor series is truncated after the second term, ordinary Newton iterations are obtained. In several cases it is possible to algebraically simplify the difference between the true value and the starting guess value. In those cases we show that it is advantageous to use the Taylor series to higher order to obtain the fast convergent method. Moreover, we will show how the coefficients of a Chebyshev polynomial can be fitted to give as little error as possible for the functions close to zero and in the same time reduce the terms in the Taylor expansion.In the paper we benchmark two example implementations of the method on the x86_64 architecture. The first is the inverse square root, where the actual table (to 12 bit precision) is provided by the processor hardware. The inverse square root is important in many application programs, including computer graphics, and explicit particle simulation codes, for instance the Monte Carlo and Molecular Dynamics methods of statistical mechanics. The other example is the arcsine function, which has a slow converging Taylor expansion and where no tables are provided by the hardware. The vectorized versions of the implementations of the inverse square root are 3.5 times faster than compiled code on the Athlon64 and about 5 times faster on the Core 2. The scalar version of the arcsine function is, depending on order and table size, between 2 and 3 times faster than the compiled code, and the vectorized version is between 3 and 4 times faster on the Athlon64, while it is between 4 and 5 times faster than the compiled version on the Core 2.
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| 5. |
- Nilsson, Mikael, et al.
(författare)
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Learning Based Image Segmentation of Pigs in a Pen
- 2014
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Ingår i: ; , s. 1-4
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Konferensbidrag (refereegranskat)abstract
- As farms are getting bigger with more animals, less manual supervision and attention can be given the animals on both group and individual level. In order not to jeopardize animal welfare, automated supervision is in some way already in use. Function and control of ventilation is already in use in modern pig stables, e.g. by the use of sensors for temperature, relative humidity and malfunction connected to alarm. However, by measuring continuously directly on the pigs, more information and more possibilities to adjust production inputs would be possible. In this work, the focus is on a key image processing algorithm aiding such a continuous system - segmentation of pigs in images from video. The proposed solution utilizes extended state-of-the-art features in combination with a structured prediction framework based on a logistic regression solver using elastic net regularization. Objective results on manually segmented images indicate that the proposed solution, based on learning, performs better than approaches suggested in recent publications addressing pig segmentation in video.
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| 6. |
- Ohlson, Martin, et al.
(författare)
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Explicit Estimators of Parameters in the Growth Curve Model with Linearly Structured CovarianceMatrices
- 2010
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Ingår i: Journal of Multivariate Analysis. - : Elsevier BV. - 0047-259X .- 1095-7243. ; 101:5, s. 1284-1295
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Tidskriftsartikel (refereegranskat)abstract
- Estimation of parameters in the classical Growth Curve model when the covariance matrix has some specific linear structure is considered. In our examples maximum likelihood estimators can not be obtained explicitly and must rely on optimization algorithms. Therefore explicit estimators are obtained as alternatives to the maximum likelihood estimators. From a discussion about residuals, a simple non-iterative estimation procedure is suggested which gives explicit and consistent estimators of both the mean and the linear structured covariance matrix.
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| 7. |
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| 8. |
- Li, Ying
(författare)
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A two step model for linear prediction, with connections to PLS
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the thesis, we consider prediction of a univariate response variable, especially when the explanatory variables are almost collinear. A two step approach has been proposed. The first step is to summarize the information in the explanatory variables via a bilinear model with a Krylov structured design matrix. The second step is the prediction step where a conditional predictor is applied. The two step approach gives us a new insight in partial least squares regression (PLS). Explicit maximum likelihood estimators of the variances and mean for the explanatory variables are derived. It is shown that the mean square error of the predictor in the two step model is always smaller than the one in PLS. Moreover, the two step model has been extended to handle grouped data. A real data set is analyzed to illustrate the performance of the two step approach and to compare it with other regularized methods.
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| 9. |
- Pielaszkiewicz, Jolanta Maria, 1985-, et al.
(författare)
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Cumulant-moment relation in free probability theory
- 2014
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Ingår i: Acta et Commentationes Universitatis Tartuensis de Mathematica. - : Tartu University Press. - 1406-2283 .- 2228-4699. ; 18:2, s. 265-278
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Tidskriftsartikel (refereegranskat)abstract
- The goal of this paper is to present and prove a cumulant-moment recurrent relation formula in free probability theory. It is convenient tool to determine underlying compactly supported distribution function. The existing recurrent relations between these objects require the combinatorial understanding of the idea of non-crossing partitions, which has been considered by Speicher and Nica. Furthermore, some formulations are given with additional use of the Möbius function. The recursive result derived in this paper does not require introducing any of those concepts. Similarly like the non-recursive formulation of Mottelson our formula demands only summing over partitions of the set. The proof of non-recurrent result is given with use of Lagrange inversion formula, while in our proof the calculations of the Stieltjes transform of the underlying measure are essential.
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| 10. |
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