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  • 1.
    Ali, W
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Georgsson, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Hellström, Thomas
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Visual tree detection for autonomous navigation in forest environment2008In: IEEE Intelligent Vehicles SymposiumConference Location: Eindhoven, NETHERLANDS, 2008, , 1144-1149 p.1144-1149 p.Conference paper (Refereed)
    Abstract [en]

    This paper describes a classification based tree detection method for autonomous navigation of forest vehicles in forest environment. Fusion of color, and texture cues has been used to segment the image into tree trunk and background objects. The segmentation of images into tree trunk and background objects is a challenging task due to high variations of illumination, effect of different color shades, non-homogeneous bark texture, shadows and foreshortening. To accomplish this, the approach has been to find the best combinations of color, and texture descriptors, and classification techniques. An additional task has been to estimate the distance between forest vehicle and the base of segmented trees using monocular vision. A simple heuristic distance measurement method is proposed that is based on pixel height and a reference width. The performance of various color and texture operators, and accuracy of classifiers has been evaluated using cross validation techniques.

  • 2.
    Cheddad, Abbas
    et al.
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Nord, Christoffer
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Hörnblad, Andreas
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Prunskaite-Hyyryläinen, Renata
    Oulu Center for Cell-Matrix Research, Biocenter Oulu, Laboratory of Developmental Biology and Department of Medical Biochemistry and Molecular Biology, Institute of Biomedicine, University of Oulu, Finland.
    Eriksson, Maria
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Georgsson, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Vainio, Seppo
    Oulu Center for Cell-Matrix Research, Biocenter Oulu, Laboratory of Developmental Biology and Department of Medical Biochemistry and Molecular Biology, Institute of Biomedicine, University of Oulu, Finland.
    Ahlgren, Ulf
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Improving signal detection in emission optical projection tomography via single source multi-exposure image fusion2013In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 21, no 14, 16584-16604 p.Article in journal (Refereed)
    Abstract [en]

    We demonstrate a technique to improve structural data obtained from Optical Projection Tomography (OPT) using Image Fusion (IF) and contrast normalization. This enables the visualization of molecular expression patterns in biological specimens with highly variable contrast values. In the approach, termed IF-OPT, different exposures are fused by assigning weighted contrasts to each. When applied to projection images from mouse organs and digital phantoms our results demonstrate the capability of IF-OPT to reveal high and low signal intensity details in challenging specimens. We further provide measurements to highlight the benefits of the new algorithm in comparison to other similar methods.

  • 3.
    Cheddad, Abbas
    et al.
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Svensson, Christoffer
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Sharpe, James
    Georgsson, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Ahlgren, Ulf
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Image processing assisted algorithms for optical projection tomography2012In: IEEE Transactions on Medical Imaging, ISSN 0278-0062, E-ISSN 1558-254X, Vol. 31, no 1, 1-15 p.Article in journal (Refereed)
    Abstract [en]

    Since it was first presented in 2002, optical projection tomography (OPT) has emerged as a powerful tool for the study of biomedical specimen on the mm to cm scale. In this paper, we present computational tools to further improve OPT image acquisition and tomographic reconstruction. More specifically, these methods provide: semi-automatic and precise positioning of a sample at the axis of rotation and a fast and robust algorithm for determination of postalignment values throughout the specimen as compared to existing methods. These tools are easily integrated for use with current commercial OPT scanners and should also be possible to implement in "home made" or experimental setups for OPT imaging. They generally contribute to increase acquisition speed and quality of OPT data and thereby significantly simplify and improve a number of three-dimensional and quantitative OPT based assessments.

  • 4.
    Courtois, Julien
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Szumski, Michal
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Georgsson, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Irgum, Knut
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Assessing the macroporous structure of monolithic columns by transmission electron microscopy2007In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 79, no 1, 335-344 p.Article in journal (Refereed)
    Abstract [en]

    A set of monolithic stationary phases representing a broad span of monomers and porogens have been characterized directly in their capillary chromatographic format by computational assessment of their pore structure from transmission electron micrographs obtained after in situ embedment of the monoliths in contrast resin, followed by dissolution of the fused-silica tubing, further encasement of the resin-embedded monolith, and microtomy. This technique has been compared to mercury intrusion, a more conventional technique for macroporosity estimation. Supplementing the embedding resin by lead methacrylate gave a negative staining, and the resulting micrographs showed a good contrast between the polymeric monoliths and the embedding resin that allowed studies on the pore formation and polymer development. The technique was also applied to a commercial monolithic silica column.

  • 5.
    Eklund, Patrik
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Georgsson, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Unravelling the thrill of metric image spaces1999In: Lecture Notes in Computer Science, ISSN 0302-9743, E-ISSN 1611-3349, Vol. 1568, 275-285 p.Article in journal (Refereed)
    Abstract [en]

    In this paper we focus on distances between textures. and develop metrics on image spaces in contexts of image transformations. Given a metric on the range space, we can generate the initial topology for the domain space. For this topology we can obtain a corresponding metric using well-known metrization constructions, also providing granularity of the metrics. Examples are drawn front the Spatial Gray Level Dependency (SGLD) transformation and the application domain is texture recognition in medical imaging.

  • 6.
    Eriksson, Anna U.
    et al.
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Svensson, Christoffer
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Hörnblad, Andreas
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Cheddad, Abbas
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Kostromina, Elena
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Eriksson, Maria
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Norlin, Nils
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Pileggi, Antonello
    Cell Transplants Center, Diabetes Research Institute, University of Miami.
    Sharpe, James
    EMBL-CRG Systems Biology Program, Centre for Genomic Regulation, Catalan Institute of Research and Advance Studies.
    Georgsson, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Alanentalo, Tomas
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Ahlgren, Ulf
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Near infrared optical projection tomography for assessments of beta-cell mass distribution in diabetes research2013In: Journal of Visualized Experiments, ISSN 1940-087X, E-ISSN 1940-087X, Vol. 71, e50238Article in journal (Refereed)
    Abstract [en]

    By adapting OPT to include the capability of imaging in the near infrared (NIR) spectrum, we here illustrate the possibility to image larger bodies of pancreatic tissue, such as the rat pancreas, and to increase the number of channels (cell types) that may be studied in a single specimen. We further describe the implementation of a number of computational tools that provide: 1/ accurate positioning of a specimen's (in our case the pancreas) centre of mass (COM) at the axis of rotation (AR)2; 2/ improved algorithms for post-alignment tuning which prevents geometric distortions during the tomographic reconstruction2 and 3/ a protocol for intensity equalization to increase signal to noise ratios in OPT-based BCM determinations3. In addition, we describe a sample holder that minimizes the risk for unintentional movements of the specimen during image acquisition. Together, these protocols enable assessments of BCM distribution and other features, to be performed throughout the volume of intact pancreata or other organs (e.g. in studies of islet transplantation), with a resolution down to the level of individual islets of Langerhans.

  • 7.
    Georgsson, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Anatomical coordinate system in bilateralregistration of mammograms2003In: SCIA 2003 / [ed] J.Bigun, T. Gustavsson, Berlin: Springer , 2003, 335-342 p.Conference paper (Refereed)
  • 8.
    Georgsson, Fredrik
    Umeå University, Faculty of Science and Technology, Computing Science.
    Differential analysis of bilateral mammograms2003In: International Journal on Pattern Recognition and Artificial Intelligence, Vol. 17, no 7, 1207-1226 p.Article in journal (Refereed)
  • 9.
    Georgsson, Fredrik
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Carlson, Stina
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    A framework for computer aided mammographic screening1998In: Digital Mammography / [ed] N. Karssemeijer, M. Thijsen, J. Hendriks, L.v. Erning, Kluwer Academic Press , 1998, 415-418 p.Conference paper (Refereed)
  • 10.
    Georgsson, Fredrik
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Christina, Olsén
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Stefan, Jansson
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Fractal Analysis of Mammograms2007In: SCIA 2007 / [ed] B. K. Ersboll, K. S. Pedersen, Berlin: Springer , 2007, 92-101 p.Conference paper (Refereed)
    Abstract [en]

    In this paper it is shown that there is a difference in local fractal dimension between imaged glandular tissue, supporting tissue and muscle tissue based on an assessment from a mammogram. By estimating the density difference at four different local dimensions (2.06, 2.33, 2.48, 2.70) from 142 mammograms we can define a measure and by using this measure we are able to distinguish between the tissue types. A ROC-analysis gives us an area under the curve-value of 0.9998 for separating glandular tissue from muscular tissue and 0.9405 for separating glandular tissue from supporting tissue. To some extent we can say that the measured difference in fractal properties is due to different fractal properties of the unprojected tissue. For example, to a large extent muscle tissue seems to have different fractal properties than glandular or supportive tissue. However, a large variance in the local dimension densities makes it difficult to make proper use of the proposed measure for segmentation purposes.

  • 11.
    Georgsson, Fredrik
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Eklund, Patrik
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    An identication of handling uncertaintieswithin medical screening: a case study within screening for breast cancer1999In: Fuzzy & Neuro-Fuzzy Systems in Medicine / [ed] Horia-Nicolai L Teodorescu, Abraham Kandel, Lakhmi C. Jain, CRC Press, 1999, 173-193 p.Chapter in book (Refereed)
  • 12.
    Georgsson, Fredrik
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Kontio, Juha
    Bennedsen, Jens
    Clark, Robin
    Matthíasdóttir, Ásrún
    Hermon, Paul
    Rouvrais, Siegfried
    Karhu, Markku
    Schrey-Niemenmaa, Katriina
    QAEMP: en verktygslåda för att utveckla ingenjörsutbildning med hjälp av kritiska vänner2015In: 5:e Utvecklingskonferensen för Sveriges ingenjörsutbildningar: Proceedings, Uppsala: Uppsala universitet, 2015, 24-26 p.Conference paper (Other academic)
    Abstract [sv]

    På denna workshop kommer vi att jobba med en process för att förbättra ingenjörsutbildning. Kärnan i denna process är en modell för Cross-Sparring där olika utbildningar agerar kritiska vänner. Grunden för Cross-Sparring utgörs av en självvärdering där utbildningsprogrammet identifierar vilka kvalitetskriterier man vill ha hjälp utifrån för att förbättra. En del av processen består i att dokumentera Best Practice som man kan dela med sig av på en Market Place och genom att koppla Best Practice till kvalitetskriterier gör dem effektivt sökbara.Utifrån detta underlag kan man sedan hitta lämpliga partners för Cross-Sparring.

  • 13.
    Nilsson, Anders
    et al.
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Georgsson, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Projective properties of fractal sets2008In: Chaos, Solitons & Fractals, ISSN 0960-0779, E-ISSN 1873-2887, Vol. 35, no 4, 786-794 p.Article in journal (Refereed)
    Abstract [en]

    In this paper, it is shown that a bound on the box dimension of a set in 3D can be established by estimating the box dimension of the discrete image of the projected set i.e. from an image in 2D. It is possible to impose limits on the Hausdorff dimension of the set by estimating the box dimension of the projected set. Furthermore, it is shown how a realistic X-ray projection can be viewed as equivalent to an ideal projection when regarding estimates of fractal dimensions.

  • 14.
    Olsen, Christina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Georgsson, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Assessing ground truth of glandular tissue2006In: Digital Mammography: 8th International Workshop, IWDM 2006, Manchester, UK, June 18-21, 2006. Proceedings, Berlin / Heidelberg: Springer , 2006, 10-17 p.Conference paper (Refereed)
    Abstract [en]

    In medical image analysis a ground truth to compare results against is of vital importance. This ground truth is often obtained from human experts. The aim of this paper is to discuss the problem related to the use of markings made by an expert panel. As a partial solution, we. propose a method to relate markings to each other in order to establish levels of agreement. By using this method we can assess the performance of, for instance, segmentation algorithms.

  • 15.
    Olsén, Christina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Georgsson, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Problems Related to Automatic Nipple Extraction2005In: Image Analysis, ISSN 0302-9743, Vol. 3540, 470-480 p.Article in journal (Refereed)
  • 16.
    Olsén, Christina
    et al.
    Umeå University, Faculty of Science and Technology, Computing Science.
    Georgsson, Fredrik
    Umeå University, Faculty of Science and Technology, Computing Science.
    Problems Related to Automatic Nipple Extraction2005In: Image Analysis: 14th Scandinavian Conference, SCIA 2005, Joensuu, Finland, June 2005, Proceedings, 2005, 470-480 p.Conference paper (Refereed)
1 - 16 of 16
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