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  • 1. Adler, J
    et al.
    Bergholm, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering (closed 20110301).
    Pagakis, S
    Parmryd, I
    Noise and colocalization in fluorescence microscopy: solving a problem2008In: Microscopy and Microanalysis, ISSN 1431-9276, E-ISSN 1435-8115, Vol. 22, no 5Article in journal (Refereed)
  • 2.
    Bergholm, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering (closed 20110301).
    Adjacency Matrices and Descriptions of Air Voids in 3D2010Report (Other academic)
  • 3.
    Bergholm, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering (closed 20110301).
    Atmospheric correction, and light scattering with 2DSOS2008Report (Other academic)
  • 4.
    Bergholm, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering (closed 20110301).
    Documentation of developed Image Segmentation and Methodology2010Report (Other academic)
  • 5.
    Bergholm, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering (closed 20110301).
    Micrometeorology and Road Conditions: a model of dependencies for identifying critical conditions in a predictive fashion2009Report (Other academic)
  • 6.
    Bergholm, Fredrik
    et al.
    KTH, School of Computer Science and Communication (CSC), Numerical Analysis and Computer Science, NADA.
    Adler, Jeremy
    Parmryd, Ingela
    Analysis of Bias in the Apparent Correlation Coefficient Between Image Pairs Corrupted by Severe Noise2010In: Journal of Mathematical Imaging and Vision, ISSN 0924-9907, E-ISSN 1573-7683, Vol. 37, no 3, p. 204-219Article in journal (Refereed)
    Abstract [en]

    The correlation coefficient r is a measure of similarity used to compare regions of interest in image pairs. In fluorescence microscopy there is a basic tradeoff between the degree of image noise and the frequency with which images can be acquired and therefore the ability to follow dynamic events. The correlation coefficient r is commonly used in fluorescence microscopy for colocalization measurements, when the relative distributions of two fluorophores are of interest. Unfortunately, r is known to be biased understating the true correlation when noise is present. A better measure of correlation is needed. This article analyses the expected value of r and comes up with a procedure for evaluating the bias of r, expected value formulas. A Taylor series of so-called invariant factors is analyzed in detail. These formulas indicate ways to correct r and thereby obtain a corrected value free from the influence of noise that is on average accurate (unbiased). One possible correction is the attenuated corrected correlation coefficient R, introduced heuristically by Spearman (in Am. J. Psychol. 15:72-101, 1904). An ideal correction formula in terms of expected values is derived. For large samples R tends towards the ideal correction formula and the true noise-free correlation. Correlation measurements using simulation based on the types of noise found in fluorescence microscopy images illustrate both the power of the method and the variance of R. We conclude that the correction formula is valid and is particularly useful for making correct analyses from very noisy datasets.

  • 7.
    Bergholm, Fredrik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Francisco, A
    On the importance of being asymmetric in stereopsis - or the use of skewed parallel cameras1998In: Int. J. of Computer Vision, Vol. 29, no 3Article in journal (Refereed)
  • 8.
    Bergholm, Fredrik
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Hamid Muhammed, Hamed
    KTH, School of Technology and Health (STH), Medical Engineering.
    Larsolle, A.
    Acquiring instantaneous multispectral imagery using a single image sensor with multiple filter mosaic2007Conference paper (Other academic)
  • 9. Callaghan, Terry V.
    et al.
    Bergholm, Fredrik
    KTH, School of Computer Science and Communication (CSC), Numerical Analysis and Computer Science, NADA.
    Christensen, Torben R.
    Jonasson, Christer
    Kokfelt, Ulla
    Johansson, Margareta
    A new climate era in the sub-Arctic: Accelerating climate changes and multiple impacts2010In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 37, no 14, p. L14705-Article in journal (Refereed)
    Abstract [en]

    Climate warming in the Swedish sub-Arctic since 2000 has reached a level at which statistical analysis shows for the first time that current warming has exceeded that in the late 1930' s and early 1940' s, and has significantly crossed the 0 degrees C mean annual temperature threshold which causes many cryospheric and ecological impacts. The accelerating temperature increase trend has driven similar trends in the century-long increase in snow thickness, loss of lake ice, increases in active layer thickness, lake water TOC (total organic carbon) concentrations and the assemblages of diatoms, and changes in tree-line location and plant community structure. Some of these impacts were not evident in the first warm period of the 20th Century. Changes in climate are associated with reduced temperature variability, particularly loss of cold winters and cool summers, and an increase in extreme precipitation events that cause mountain slope instability and infrastructure failure. The long term records of multiple, local environmental factors compiled here for the first time provide detailed information for adaptation strategy development while dramatic changes in an environment particularly vulnerable to climate change highlight the need to adopt global mitigation strategies.

  • 10.
    Hamid Muhammed, Hamed
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Bergholm, Fredrik
    KTH, School of Technology and Health (STH), Medical Engineering.
    A system for multi- and hyperspectral imaging2004Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Arrangement for the production of instantaneous or non-instantaneous multi-band images, to be transformed into multi- or hyperspectral images, comprising light collecting means, an image sensor array, and an instantaneous colour separating means, positioned before the image sensor array, and uniform spectral filters, for restricting imaging to certain parts of the electromagnetic spectrum. A filter unit is positioned before the colour separating means in the optical path in, or close to, converged light. Each filter mosaic consists of a multitude of homogeneous filtering regions. The transmission curves of the filtering regions of a colour or spectral filter mosaic can be partly overlapping, in addition to overlap between these transmission curves and those belonging to the filtering regions of the colour separating means.; The transmission curves of the colour or spectral filter mosaics and the colour separating means are suitably spread out in the intervals of a spectrum to be studied.

  • 11.
    Hamid Muhammed, Hamed
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Bergholm, Fredrik
    KTH, School of Technology and Health (STH), Medical Engineering.
    Camera-spectrometer for instantaneous multi- and hyperspectral imaging2005Conference paper (Other academic)
  • 12.
    Hamid Muhammed, Hamed
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Bergholm, Fredrik
    KTH, School of Technology and Health (STH), Medical Engineering.
    Camera-spectrometer for multi- and hyperspectral imaging2005Conference paper (Other academic)
  • 13.
    Hamid Muhammed, Hamed
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Bergholm, Fredrik
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Sensitivity Analysis of Multichannel Images Intended for Instantaneous Imaging Spectrometry Applications2010In: SIAM Journal on Imaging Sciences, ISSN 1936-4954, E-ISSN 1936-4954, Vol. 3, no 1, p. 79-109Article in journal (Refereed)
    Abstract [en]

    This paper presents a sensitivity analysis of using instantaneous multichannel two-dimensional (2D) imaging to achieve instantaneous 2D imaging spectroscopy. A simulated multiple-filter mosaic was introduced and used to acquire multichannel data which were transformed into spectra. The feasibility of two different transformation approaches (the concrete pseudoinverse approach and a statistical approach) was investigated through extensive experimental tasks. A promising statistical method was identified to be used for accurate estimation of spectra from multichannel data. Comparison between estimated and measured spectra shows that higher estimation accuracy can be achieved when using a larger number of usable multiple-filter combinations in the mosaic.

  • 14.
    Herling, L.
    et al.
    Karolinska Inst, Dept Clin Sci Intervent & Technol CLINTEC, Stockholm, Sweden.;Karolinska Univ Hosp, Dept Obstet & Gynecol, Ctr Fetal Med, Stockholm, Sweden..
    Johnson, Jonas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems. Karolinska Univ Hosp, Dept Obstet & Gynecol, Ctr Fetal Med, Stockholm, Sweden..
    Ferm-Widlund, K.
    Karolinska Univ Hosp, Dept Obstet & Gynecol, Ctr Fetal Med, Stockholm, Sweden..
    Bergholm, F.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems.
    Elmstedt, N.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems.
    Lindgren, P.
    Karolinska Inst, Dept Clin Sci Intervent & Technol CLINTEC, Stockholm, Sweden.;Karolinska Univ Hosp, Dept Obstet & Gynecol, Ctr Fetal Med, Stockholm, Sweden..
    Sonesson, S. -E
    Acharya, G.
    Karolinska Inst, Dept Clin Sci Intervent & Technol CLINTEC, Stockholm, Sweden.;Karolinska Univ Hosp, Dept Obstet & Gynecol, Ctr Fetal Med, Stockholm, Sweden.;UiT Arctic Univ Norway, Dept Clin Med, Womens Hlth & Perinatol Res Grp, Tromso, Norway..
    Westgren, M.
    Karolinska Inst, Dept Clin Sci Intervent & Technol CLINTEC, Stockholm, Sweden.;Karolinska Univ Hosp, Dept Obstet & Gynecol, Ctr Fetal Med, Stockholm, Sweden..
    Automated analysis of fetal cardiac function using color tissue Doppler imaging in second half of normal pregnancy2019In: Ultrasound in Obstetrics and Gynecology, ISSN 0960-7692, E-ISSN 1469-0705, Vol. 53, no 3, p. 348-357Article in journal (Refereed)
    Abstract [en]

    Objectives Color tissue Doppler imaging (cTDI) is a promising tool for the assessment of fetal cardiac function. However, the analysis of myocardial velocity traces is cumbersome and time-consuming, limiting its application in clinical practice. The aim of this study was to evaluate fetal cardiac function during the second half of pregnancy and to develop reference ranges using an automated method to analyze cTDI recordings from a cardiac four-chamber view. Methods This was a cross-sectional study including 201 normal singleton pregnancies between 18 and 42weeks of gestation. During fetal echocardiography, a four-chamber view of the heart was visualized and cTDI was performed. Regions of interest were positioned at the level of the atrioventricular plane in the left ventricular (LV), right ventricular (RV) and septal walls of the fetal heart, to obtain myocardial velocity traces that were analyzed offline using the automated algorithm. Peak myocardial velocities during atrial contraction (Am), ventricular ejection (Sm) and rapid ventricular filling, i. e. early diastole (Em), as well as the Em/Am ratio, mechanical cardiac time intervals and myocardial performance index (cMPI) were evaluated, and gestational age-specific reference ranges were constructed. Results At 18 weeks of gestation, the peak myocardial velocities, presented as fitted mean with 95% CI, were: LV Am, 3.39 (3.09-3.70) cm/s; LV Sm, 1.62 (1.46-1.79) cm/s; LV Em, 1.95 (1.75-2.15) cm/s; septal Am, 3.07 (2.80-3.36) cm/s; septal Sm, 1.93 (1.81-2.06) cm/s; septal Em, 2.57 (2.32-2.84) cm/s; RV Am, 4.89 (4.59-5.20) cm/s; RV Sm, 2.31 (2.16-2.46) cm/s; and RV Em, 2.94 (2.69-3.21) cm/s. At 42weeks of gestation, the peak myocardial velocities had increased to: LV Am, 4.25 (3.87-4.65) cm/s; LV Sm, 3.53 (3.19-3.89) cm/s; LV Em, 4.55 (4.18-4.94) cm/s; septal Am, 4.49 (4.17-4.82) cm/s; septal Sm, 3.36 (3.17-3.55) cm/s; septal Em, 3.76 (3.51-4.03) cm/s; RV Am, 6.52 (6.09-6.96) cm/s; RV Sm, 4.95 (4.59-5.32) cm/s; and RV Em, 5.42 (4.99-5.88) cm/s. The mechanical cardiac time intervals generally remained more stable throughout the second half of pregnancy, although, with increased gestational age, there was an increase in duration of septal and RV atrial contraction, LV pre-ejection and septal and RV ventricular ejection, while there was a decrease in duration of septal postejection. Regression equations used for the construction of gestational age-specific reference ranges for peak myocardial velocities, Em/Am ratios, mechanical cardiac time intervals and cMPI are presented. Conclusion Peak myocardial velocities increase with gestational age, while the mechanical time intervals remain more stable throughout the second half of pregnancy. Using an automated method to analyze cTDI-derived myocardial velocity traces, it was possible to construct reference ranges, which could be used in distinguishing between normal and abnormal fetal cardiac function.

  • 15.
    Herling, L.
    et al.
    Karolinska Inst, Dept Clin Sci Intervent & Technol CLINTEC, Stockholm, Sweden.;Karolinska Univ Hosp, Dept Obstet & Gynecol, Ctr Fetal Med, Stockholm, Sweden..
    Johnson, Jonas
    KTH, School of Technology and Health (STH), Medical Engineering. Karolinska Univ Hosp, Dept Obstet & Gynecol, Ctr Fetal Med, Stockholm, Sweden.
    Ferm-Widlund, K.
    Karolinska Univ Hosp, Dept Obstet & Gynecol, Ctr Fetal Med, Stockholm, Sweden..
    Bergholm, Fredrik
    KTH, School of Technology and Health (STH), Medical Engineering.
    Lindgren, P.
    Karolinska Univ Hosp, Dept Obstet & Gynecol, Ctr Fetal Med, Stockholm, Sweden..
    Sonesson, S. -E
    Acharya, G.
    Karolinska Inst, Dept Clin Sci Intervent & Technol CLINTEC, Stockholm, Sweden.;Karolinska Univ Hosp, Dept Obstet & Gynecol, Ctr Fetal Med, Stockholm, Sweden.;UiT Arctic Univ Norway, Dept Clin Med, Womens Hlth & Perinatol Res Grp, Tromso, Norway..
    Westgren, M.
    Karolinska Inst, Dept Clin Sci Intervent & Technol CLINTEC, Stockholm, Sweden.;Karolinska Univ Hosp, Dept Obstet & Gynecol, Ctr Fetal Med, Stockholm, Sweden..
    Automated analysis of fetal cardiac function using color tissue Doppler imaging2018In: Ultrasound in Obstetrics and Gynecology, ISSN 0960-7692, E-ISSN 1469-0705, Vol. 52, no 5, p. 599-608Article in journal (Refereed)
    Abstract [en]

    Objective To evaluate the feasibility of automated analysis of fetal myocardial velocity recordings obtained by color tissue Doppler imaging (cTDI). Methods This was a prospective cross-sectional observational study of 107 singleton pregnancies >= 41 weeks of gestation. Myocardial velocity recordings were obtained by cTDI in a long-axis four-chamber view of the fetal heart. Regions of interest were placed in the septum and the right (RV) and left (LV) ventricular walls at the level of the atrioventricular plane. Peak myocardial velocities and mechanical cardiac time intervals were measured both manually and by an automated algorithm and agreement between the two methods was evaluated. Results In total, 321 myocardial velocity traces were analyzed using each method. It was possible to analyze all velocity traces obtained from the LV, RV and septal walls with the automated algorithm, and myocardial velocities and cardiac mechanical time intervals could be measured in 96% of all traces. The same results were obtained when the algorithm was run repeatedly. The myocardial velocities measured using the automated method correlated significantly with those measured manually. The agreement between methods was not consistent and some cTDI parameters had considerable bias and poor precision. Conclusions Automated analysis of myocardial velocity recordings obtained by cTDI was feasible, suggesting that this technique could simplify and facilitate the use of cTDI in the evaluation of fetal cardiac function, both in research and in clinical practice.

  • 16.
    Johnson, Jonas
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Manouras, Aristomenis
    KTH, School of Technology and Health (STH), Medical Engineering. Karolinska Institute, Sweden.
    Bergholm, Fredrik
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Brodin, Lars Åke
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Agewall, S.
    Henareh, L.
    The early diastolic myocardial velocity: A marker of increased risk in patients with coronary heart disease2014In: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 34, no 5, p. 389-396Article in journal (Refereed)
    Abstract [en]

    Objective: Tissue Doppler imaging (TDI) is a promising echocardiographic modality allowing quantification of myocardial performance. However, the prognostic potential of TDI in patients with acute myocardial infarction (AMI) is not yet investigated. We sought to explore the ability of TDI in identifying patients at risk for new cardiovascular events after AMI. Methods: One hundred and nineteen patients with AMI were recruited prospectively (mean age 61 years; range 32-81 years of age). Patients with diabetes mellitus (DM) were excluded. Echocardiography was performed 3-12 months after AMI. Two-dimensional (2-D) and TDI variables were recorded. The patients were followed during a mean period of 4·6 years (range 1-8 years). The primary end-point was defined as any of the following: death from any cause, non-fatal reinfarction or stroke, unstable angina pectoris, congestive heart failure requiring hospitalization and coronary revascularization procedure. Results: Thirty patients had some form of cardiovascular events during follow-up. Seven patients had cardiovascular death, 13 patients had reinfarction and four patients had a stroke. New angina or unstable angina was recorded in 21 patients. Of these patients, 13 underwent percutaneous coronary angioplasty (PCI) or coronary artery bypass grafting (CABG). The early diastolic myocardial velocity (Em) emerged as the only echocardiographic variable that offered a clear differentiation between patients that presented with new cardiovascular (CV) events as compared to the corresponding group without any CV events at follow-up (P<0·05). In multivariate statistical analysis and after adjustment for age, sex, total cholesterol, body mass index (BMI) and other baseline characteristics, Em remained as independent predictors of CV events (HR, 1·18, 95% CI, 1·02-1·36; P<0·05). However, none of the investigated variables evolved as an independent predictor of cardiovascular morbidity and mortality. Conclusion: Em appears to be a sensitive echocardiographic index in identifying non-diabetic patients with AMI at risk of new cardiovascular events.

  • 17.
    Sefi, Sandy
    et al.
    KTH, School of Computer Science and Communication (CSC), Numerical Analysis and Computer Science, NADA.
    Bergholm, Fredrik
    KTH, School of Computer Science and Communication (CSC), Numerical Analysis and Computer Science, NADA.
    Modeling and Extrapolating Highfrequency Electromagnetic Currents on Conducting Obstacles2005Conference paper (Refereed)
    Abstract [en]

    We present a current-based approach to high frequency approximate techniques in Computational Electromagnetics(CEM). Our goal is to numerically model the behavior of electromagnetic and surface current vectorfields at high frequency, using information extracted from lower frequency solutions.

  • 18.
    Sefi, Sandy
    et al.
    KTH, Superseded Departments, Numerical Analysis and Computer Science, NADA.
    Bergholm, Fredrik
    KTH, Superseded Departments, Numerical Analysis and Computer Science, NADA.
    Hagdahl, Stefan
    Modular Approach to GTD in the Context of Solving Large Hybrid Problems2000Conference paper (Refereed)
  • 19.
    Sefi, Sandy
    et al.
    KTH, School of Computer Science and Communication (CSC), Numerical Analysis and Computer Science, NADA.
    Berghom, Fredrik
    KTH, School of Computer Science and Communication (CSC), Numerical Analysis and Computer Science, NADA.
    Extrapolation and Modelling of Method of Moments Currents on a PEC surface2005In: Mathematical Modeling of Wave Phenomena, 2005, p. 92-99Conference paper (Refereed)
    Abstract [en]

    We present a current-based approach to high frequency approximation techniques. Our goal is to numerically model the behaviour of electromagnetic and surface current vector fields at medium-range or high frequency, using information extracted from lower frequency solutions.

  • 20.
    Tafesse, Solomon
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Fernlund, Joanne
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Bergholm, Fredrik
    KTH, School of Technology and Health (STH), Medical Engineering.
    Digital sieving-Matlab based 3-D image analysis2012In: Engineering Geology, ISSN 0013-7952, E-ISSN 1872-6917, Vol. 137-138, p. 74-84Article in journal (Refereed)
    Abstract [en]

    A new image analysis technique for determining the three-dimensional size and shape distribution of coarse particles has been developed. It entails acquiring a pair of images, one each of the maximum and minimum projected area of the particles. Glow-In-the-Dark beads were used to create luminous background, thus it is named the GID method. In this study the size and shape distribution of four coarse-grained samples, size varies from 2 to 20. cm, have been analyzed. The size distribution of the samples obtained from the GID analysis is comparable to sieve analysis results, and has an extra advantage of being applicable in the field. The algorithm was developed in Matlab; therefore users could make some optimization in the program to meet their own needs as the program code is open source.

  • 21.
    Tafesse, Solomon
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Fernlund, Joanne M. Robison
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Sun, Wenjuan
    Bergholm, Fredrik
    KTH, School of Technology and Health (STH), Medical Engineering.
    Evaluation of image analysis methods for the quantification of particle angularityIn: Sedimentology, ISSN 0037-0746, E-ISSN 1365-3091Article in journal (Other academic)
  • 22.
    Tafesse, Solomon
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Robison Fernlund, Joanne M.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Sun, Wenjuan
    Bergholm, Fredrik
    KTH, School of Technology and Health (STH), Medical Engineering.
    Evaluation of image analysis methods used for quantification of particle angularity2013In: Sedimentology, ISSN 0037-0746, E-ISSN 1365-3091, Vol. 60, no 4, p. 1100-1110Article in journal (Refereed)
    Abstract [en]

    Angularity is an important parameter in the characterization of particle morphology that is used to interpret the transport history of particles in sedimentary deposits. In the past, visual classification using silhouette charts was widely used to determine particle angularity, but this approach is subjective and time-consuming. With advances in modern image analysis techniques and low-cost software packages, it is possible to rapidly quantify particle angularity more objectively than using visual classification methods. This study re-examines the performance of three existing image analysis methods and one new image analysis procedure, applied to six rock and sediment samples that were visually different in angularity. To facilitate comparison between the angularity results, measurements were reduced to rankings for each aggregate sample. These results show that the four image analysis methods rank the angularity of the samples differently, and that none rank the mean angularity index in the same order as the angularity ranking using visual classification. Therefore, further research is needed to develop an image analysis method that can quantify the angularity of sedimentary particles more precisely.

  • 23. Wang, W
    et al.
    Bergholm, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Froth delineation based on image classification2003In: Minerals Engineering, Vol. 16Article in journal (Refereed)
  • 24. Zhang, W
    et al.
    Bergholm, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Multiscale blur estimation and edge type classification for scene analysis1997In: Int. J. of Computer Vision, Vol. 24, no 3Article in journal (Refereed)
1 - 24 of 24
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