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PURPOSE: Neglecting imaging gradients in b-value calculations has been a documented issue for decades and remains unaccounted for in the current postprocessing pipelines. This omission may introduce inaccuracies that propagate into diffusion parameter estimates, such as in ADC and DTI analysis. Because intravoxel incoherent motion (IVIM) makes use of low b-values, these inaccuracies may be of grea
Presentationsrubrik på en eller två rader Resultat av resvaneundersökning för Lunds universitet inom ramen för CoAction Lund hösten 2024 Innehållsförteckning 2 1. Inledning 5 2. Övergripande utgångsläge 2024 7 Hur nära 1/3-delsmålet? 8 Bostadsort 10 Antal dagar på arbetet respektive på distans 11 Drivmedel 13 3. Arbetspendling 14 Färdmedelsfördelning vid resor till arbetet 15 Insatser för att unde
Presentationsrubrik på en eller två rader Resultat av resvaneundersökning för Lunds universitet inom ramen för CoAction Lund hösten 2024 Version 2.0 Innehållsförteckning 2 1. Inledning 5 2. Övergripande utgångsläge 2024 7 Hur nära 1/3-delsmålet? 8 Bostadsort 10 Antal dagar på arbetet respektive på distans 11 Drivmedel 13 3. Arbetspendling 14 Färdmedelsfördelning vid resor till arbetet 15 Insatser
Asphalt is made of a mixture of stones of different sizes and a binder called bitumen, the size distribution of the stones is determined by the recipe of the asphalt. One quality check of asphalt is to see if the real size distribution of asphalt samples is consistent with the recipe. This is usually done by first extracting the binder using methylenchloride and the sieving the stones and see how
Ultrasound imaging of the heart is a non-invasive method widely used for different applications. One of them is to measure the blood volume in the left ventricle at different stages of the heart cycle. This demands a proper segmentation of the left ventricle and a (semi-) automated method would decrease intra-variability as well as workload. This paper presents a semi-automated segmentation method t
The field of high dynamic range imaging addresses the problem of capturing and displaying the large range of luminance levels found in the world, using devices with limited dynamic range. In this paper we present a novel tone mapping algorithm that is based on $K$-means clustering. Using dynamic programming we are able to, not only solve the clustering problem efficiently, but also find the global
The generation of maps in real-time web-services introduces challenges concerning map legibility. As these services lack the important input of a traditional cartographer, analytical measures of the legibility are called for. The aim of this study was to develop such legibility measures, and to evaluate them with the help of expert users. Measures of the amount of information, spatial distribution
Indisputably Normalized Cuts is one of the most popular segmentation algorithms in pattern recognition and computer vision. It has been applied to a wide range of segmentation tasks with great success. A number of extensions to this approach have also been proposed, including ones that can deal with multiple classes or that can incorporate a priori information in the form of grouping constraints.
It is commonly believed that higher order smoothness should be modeled using higher order interactions. For example, 2nd order derivatives for deformable (active) contours are represented by triple cliques. Similarly, the 2nd order regularization methods in stereo predominantly use MRF models with scalar (1D) disparity labels and triple clique interactions. In this paper we advocate a largely over
In this paper we direct our attention to the problem of discretization effects in intensity transformations of images. We propose to use the Wasserstein metric (also known as the Earth mover distance) to bootstrap the transformation process. The Wasserstein metric gives a mapping between gray levels that we use to direct our image mapping. In order to spatially regularize the image mapping we appl
Calibration of network nodes using only time differences of arrival (TDOA) measurements opens up for interesting applications in wireless ad-hoc sensor networks, e.g. finding the positions of cell phones by only ambient sounds or radio. We present two novel approaches for the problem of self-calibration of network nodes using only TDOA when both receivers and transmitters are unsynchronized. We co
Multiple rotation averaging is an important problem in computer vision. The problem is challenging because of the nonlinear constraints required to represent the set of rotations. To our knowledge no one has proposed any globally optimal solution for the case of simultaneous updates of the rotations. In this paper we propose a simple procedure based on Lagrangian duality that can be used to verify
The state of the art for large database object retrieval in images is based on quantizing descriptors of interest points into visual words. High similarity between matching image representations (as bags of words) is based upon the assumption that matched points in the two images end up in similar words in hard assignment or in similar representations in soft assignment techniques. In this paper w
https://www.mgeo.lu.se/ola-olsson - 2026-09-13
https://www.nateko.lu.se/sv/ola-olsson - 2026-09-13
https://www.geologi.lu.se/leif-johansson - 2026-09-13
We study and solve the previously unstudied problem of finding both transmitter and receiver positions using only time of arrival (TOA) measurements when there is a difference in dimensionality between the affine subspaces spanned by receivers and transmitters. Anchor-free TOA network calibration has uses both in radio, radio strength and sound applications, such as calibrating ad hoc microphone a
The semantic formalism reference attribute grammars (RAGs) allows graphs to be superimposed on abstract syntax trees. This paper investigates how RAGs can be used to model visual languages, with a case study of a control language that also has a textual syntax. The language contains blocks on which a total execution order is defined based on connections and layout information. One strength of RAGs
In this paper, we develop a system for microphone selflocalization based on ambient sound, without any assumptions on the 3D locations of the microphones and sound sources. We aim at developing a system capable of dealing with multiple moving sound sources. We will show that this is possible given that there are instances where there are only one dominating sound source. In the first step of the s
Segmentation is an important task in all kinds of image analysis. In medical image analysis segmentation has a great clinical value since the aim could be to localize organs or pathologies in order to raise the quality of diagnoses. This thesis consists of three papers where different segmentation techniques have been applied to different imaging modalities. In the first paper a full computer assi
