Tomas Gustavsson

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28ranked-venue papers
2as first author
16since 2021 · last 2026
—ORCID · conflict

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Software engineering, systems software and programming languages · 20 · 2 first-author · 16 since 2021Applied, interdisciplinary, general and emerging computing · 7 · 3 since 2021Graphics, computer vision, multimedia, augmented reality and games · 3Artificial intelligence and machine learning · 2Human-computer interaction and ubiquitous computing · 2
YearPublicationVenuePosition
2026 A comparative analysis of industrial involvement and licensing in the open source software ecosystems of four IoT standards
abstract
Context: IoT standards are vital for interoperability and longevity, with Open Source Software (OSS) implementations preventing vendor lock-in. These implementations form vast software ecosystems on platforms like GitHub, where industrial participation is crucial. Goal: This study characterizes industrial involvement (participation, leadership, collaboration) across the software ecosystems of four IoT standards (LwM2M, NB-IoT, CoAP, Zigbee) from different standards-setting organizations. It also investigates how software licensing, particularly OSS licenses, reflects and shapes this involvement. Method: We analyzed software projects related to these standards that are publicly available on the GitHub platform, examining authorship of commits, bug reports, pull requests, and metadata like licenses. We identified organizational affiliations (corporate or academic) of contributors to assess their presence and leadership. We performed a licensing analysis to understand the legal frameworks governing these projects. Results: Our research shows significant diversity in ecosystem scale and activity, with a consistent pattern of major corporate and organizational leadership in highly active projects. Despite robust institutional involvement, a pervasive issue is the widespread absence of explicit software licenses, even in collaborative and active repositories. When licenses are present, permissive OSS licenses (e.g., Apache-2.0, MIT) dominate. This indicates a complex and often ambiguous legal landscape. Conclusion: IoT standard ecosystem growth is driven by established organizations. Addressing the prevalent lack of licensing is crucial for fostering clearer collaboration, mitigating legal risks, and ensuring long-term sustainability and adoption of these foundational technologies.
Gregorio Robles, Jonas Gamalielsson, Björn Lundell, Christoffer Brax, Tomas Persson, Anders Mattsson, Tomas Gustavsson, Jonas Feist, Jonas Öberg
J. Syst. Softw.7
2025 It all starts with structure: investigating learning dynamics in large-scale agile software development
abstract
Agile software development (ASD) methods have increasingly been used in large-scale software development projects. While ASD emphasizes the importance of social interactions between practitioners for continuous reflection and knowledge sharing, these learning activities become incredibly challenging in large-scale projects. Drawing on well-established theoretical concepts, we posit that learning in large-scale ASD projects requires a suitable environment that empowers practitioners to openly and frequently engage in social interactions necessary for reflection and knowledge sharing. We hypothesize that several team-level factors shape individuals’ perceptions about the learning environment and learning activities in their projects and ultimately influence their learning behavior. To test our model, we collected survey responses from practitioners working in large-scale ASD projects in five Swedish companies (N=159). The data was analyzed using confirmatory factor analysis (CFA) and structural equation modeling (SEM). The results show that team structure plays a crucial role in promoting team cohesion and reflexivity, which, alongside knowledge sharing, contribute to learning. Our study provides ASD development research with a theoretically informed understanding of the interrelationship between the learning environment and learning activities in large-scale ASD. Our results guide practitioners in fostering suitable learning environments and enhancing learning in large-scale ASD.
Muhammad Ovais Ahmad, Hadi Ghanbari, Tomas Gustavsson, Bikesh Raj Upreti
J. Syst. Softw.3
2025 Job satisfaction at risk: Measuring the role of process debt in agile software development
abstract
Process debt (PD) in agile software development represents inefficiencies that undermine team performance and job satisfaction. This study investigates the quantitative impact of PD on job satisfaction within agile teams, surveying 191 participants from two software development organizations. Our research examines five PD types: Process Unsuitability, Roles Debt, Synchronization Debt, Documentation Debt, and Infrastructure Debt. Using multiple regression analysis, our model explains approximately 33.8 % of the variance in job satisfaction. Among the five PD types, Process Unsuitability and Roles Debt emerged as statistically significant predictors of reduced job satisfaction. These findings indicate that certain forms of PD have a measurable negative impact on developers' perceptions of their work environment. By identifying which PD types most strongly influence job satisfaction, this research offers empirically grounded insights that can inform targeted interventions. Understanding and addressing the most impactful PD categories may help organizations refine agile processes, thereby mitigating the detrimental effects of process inefficiencies on job satisfaction.
Tomas Gustavsson, Muhammad Ovais Ahmad, Hina Saeeda
J. Syst. Softw.1
2024 Non- Technical Aspects of Technical Debt in the Context of Large-Scale Agile Development: A Qualitative Study
abstract
Scaling agile approaches in large company context is prone to technical debt due to large number of teams of different size, level of expertise and their need for management and communication. The goal of this study is to investigate the phenomenon of non-technical debt related issues in the context of large-scale agile software development. To achieve this goal, eleven experts from two multinational companies were inter-viewed as part of the the case study. The analysis results revealed four non-technical aspects of technical debt that are present in large-scale agile context. These are people, social, documentation and process debt aspects. Furthermore, the findings suggest that lack of communication, collaboration and cooperation are the key contributors to identified debt aspects, and that many of the causes for debts are stemming from a culture of not developing rules, protocols, or guidelines. Implementing ground rules to improve quality seems to mitigate several of the identified debt types.
Muhammad Ovais Ahmad, Tomas Gustavsson, Andrej Katin, Nebojsa Tausan, Vladimir Mandic
SEAA2
2024 Exploring Process Debt in Large-Scale Agile Software Development For Secure Telecom Solutions
abstract
Background: Agile methodologies emphasise iterative development, customer collaboration, and flexibility in software development. However, challenges arise when agile practices are adopted in larger projects. Process inefficiencies and redundancies, known as process debt, result from the compounded complexities of expanding agile processes and workflows. However, strategies to understand and tackle it remain markedly inadequate.
Hina Saeeda, Muhammad Ovais Ahmad, Tomas Gustavsson
TechDebt@ICSE3
2024 The Pandora's box of social, process, and people debts in software engineering
abstract
Abstract In software engineering, technical debt (TD) has been widely investigated, but debt regarding social issues, people, and processes has not been explored as much. It should be noted here that we use nontechnical debt (NTD) as an umbrella term to cover social, process, and people debts. Although the number of studies on NTD in software is increasing, the majority of them are descriptive rather than rigorous, and there is no systematic development of cumulative knowledge. As a result, identifying the fundamental causes of NTD and the associated mitigation techniques in software engineering is challenging. Therefore, this study investigates the scientific evidence regarding NTD till date by conducting a systematic mapping review of software engineering research between January 2000 and October 2021. The search strategy resulted in 175 studies, 17 of which were identified as unique and relevant primary papers. The primary studies show that NTD and TD are inextricably linked. In addition, this study also captured a plethora of causes and mitigation strategies for managing NTD and thus makes four important contributions: (i) highlighting state‐of‐the‐art NTD research; (ii) identification of the reported causes and mitigation strategies in the primary papers; and (iii) determination of opportunities for future NTD research.
Muhammad Ovais Ahmad, Tomas Gustavsson
J. Softw. Evol. Process.2
2024 Correction to: On business adoption and use of reproducible builds for open and closed source software
Simon Butler 0001, Jonas Gamalielsson, Björn Lundell, Christoffer Brax, Anders Mattsson, Tomas Gustavsson, Jonas Feist, Bengt Kvarnström, Erik Lönroth
Softw. Qual. J.6
2024 Navigating social debt and its link with technical debt in large-scale agile software development projects
abstract
Abstract Agile methodologies have emerged as transformative paradigms in the ever-evolving software development landscape, emphasizing iterative development, customer collaboration, and adaptability. As the scope and complexity of projects and organizations expand, applying agile principles within the context of Large-Scale Agile Development (LSAD) encounters distinctive challenges. The majority of challenges encountered in LSAD, technical and non-technical, are attributed to the accrual of social debt. However, a conspicuous gap remains in understanding and addressing social debt in LSAD. This study aims to fill this void by investigating social debt in LSAD through an in-depth industrial case study with a leading Nordic company specializing in telecommunications software and services and focusing on producing secure 5G network solutions. The study investigates the causes of LSAD’s social debt and examines its impacts on secure 5G telecom software development. By addressing these objectives, this research sheds light on a critical aspect of LSAD’s social debt, caused by 3C challenges(communication, coordination and collaboration), social confines challenges, community smells challenges, and organisational social challenges in the telecom sector that have been underrepresented in the existing literature.
Hina Saeeda, Muhammad Ovais Ahmad, Tomas Gustavsson
Softw. Qual. J.3
2023 Multivocal Literature Review on Non-Technical Debt in Software Development: An Exploratory Study
Hina Saeeda, Muhammad Ovais Ahmad, Tomas Gustavsson
ENASE3
2023 Customised Roles in Scrum Teams for the Development of Secure Solution
abstract
This research paper examines the implementation and impact of customised roles in large-scale agile software development teams, specifically within the Scrum framework. This is a single case study based on 15 practitioners' interviews from a Swedish software company to review the dynamics of role customisation. The two customised roles of Product Guardians and Security Masters are crucial for addressing complex secure software development, maintaining product quality and security, and fostering team self-organisation. The study also uncovers challenges associated with role customisation, such as the potential overburdening of individuals and disruption of selforganisation. The findings contribute to the discourse on agile methods' adaptability and provide practical insights for organisations considering similar role customisations. Furthermore, the research opens the door for future exploration of organization-wide roles that promote selforganisation.
Muhammad Ovais Ahmad, Tomas Gustavsson, Hina Saeeda
SEAA2
2023 On business adoption and use of reproducible builds for open and closed source software
abstract
Abstract Reproducible builds (R-Bs) are software engineering practices that reliably create bit-for-bit identical binary executable files from specified source code. R-Bs are applied in some open source software (OSS) projects and distributions to allow verification that the distributed binary has been built from the released source code. The use of R-Bs has been advocated in software maintenance and R-Bs are applied in the development of some OSS security applications. Nonetheless, industry application of R-Bs appears limited, and we seek to understand whether awareness is low or if significant technical and business reasons prevent wider adoption. Through interviews with software practitioners and business managers, this study explores the utility of applying R-Bs in businesses in the primary and secondary software sectors and the business and technical reasons supporting their adoption. We find businesses use R-Bs in the safety-critical and security domains, and R-Bs are valuable for traceability and support collaborative software development. We also found that R-Bs are valued as engineering processes and are seen as a badge of software quality, but without a tangible value proposition. There are good engineering reasons to use R-Bs in industrial software development, and the principle of establishing correspondence between source code and binary offers opportunities for the development of further applications.
Simon Butler 0001, Jonas Gamalielsson, Björn Lundell, Christoffer Brax, Anders Mattsson, Tomas Gustavsson, Jonas Feist, Bengt Kvarnström, Erik Lönroth
Softw. Qual. J.6
2022 Agile Enterprise Transformations: Surveying the Many Facets of Agility for the Hybrid Era
abstract
Agile companies are not uniform. Consequently, agile transformations are conceived broadly, ranging from adopting agile methods and practices in software development teams or functions to building all-encompassing enterprise agility. Moreover, the targeted effects of agility may vary, and the success of transformations and the attainment of agility are measured in various ways. In this paper, based on a recent industrial survey study, we scrutinize holistically why companies want to transform, what types of agility they are aiming at, and how they gauge transformations. The survey data was collected during the COVID-19 pandemic in 2020. Most of the respondents were in large or very large companies in Finland and Sweden in diverse industry domains. The main findings indicate that there are many reasons for companies to transform both to improve external outcomes (fore mostly responsiveness) and to develop internal capabilities (adaptability, organizational learning). Companies seemed to have aims and goals with respect to all types of agility, including business agility. As the nature of transformations and the companies’ aims and goals vary, the transformations follow various means and measures. As a conclusion, for the hybrid era, we advise companies to consider how agility has benefited during the pandemic era, how hybrid work possibly affects the goals for agile transformations and the different facets of agility, and how to sustain agility in hybrid work.
Petri Kettunen, Tomas Gustavsson, Maarit Laanti, Andreas Tjernsten, Tommi Mikkonen, Tomi Männistö
SEAA2
2022 An Exploration of Openness in Hardware and Software Through Implementation of a RISC-V Based Desktop Computer
abstract
Open hardware and open source software platforms bring benefits to both implementers and users in the form of system adaptability and maintainability, and through the avoidance of lock-in, for example. Development of the RISC-V Instruction Set Architecture and processors during the last ten years has made the implementation of a desktop computer using open hardware, including open processors, and open source software an approaching possibility. We use the SiFive Unmatched development board and Ubuntu Linux, and the recorded experiences of system builders using the Unmatched board to explore the extent to which it is possible to create an open desktop computer. The work identifies current limitations to implementing an open computer system, which lie mainly at the interface between the operating system and hardware components. Potential solutions to the challenges uncovered are proposed, including greater consideration of openness during the early stages of product design. A further contribution is made by an account of the synergies arising from open collaboration in a private-collective innovation process.
Simon Butler 0001, Jonas Gamalielsson, Björn Lundell, Christoffer Brax, Tomas Persson, Anders Mattsson, Tomas Gustavsson, Jonas Feist, Jonas Öberg
OpenSym7
2022 On Engagement with Open Source Software, Open Source Hardware, and Standard Setting: The Case of White Rabbit
abstract
No abstract available.
Jonas Gamalielsson, Björn Lundell, Simon Butler 0001, Christoffer Brax, Tomas Persson, Anders Mattsson, Tomas Gustavsson, Jonas Feist, Jonas Öberg
OpenSym7
2022 Considerations and challenges for the adoption of open source components in software-intensive businesses
abstract
Component-Based Software Development is a conventional way of working for software-intensive businesses and Open Source Software (OSS) components are frequently considered by businesses for adoption and inclusion in software products. Previous research has found a variety of practices used to support the adoption of OSS components, including formally specified processes and less formal, developer-led approaches, and that the practices used continue to develop. Evolutionary pressures identified include the proliferation of available OSS components and increases in the pace of software development as businesses move towards continuous integration and delivery. We investigate work practices used in six software-intensive businesses in the primary and secondary software sectors to understand current approaches to OSS component adoption and the challenges businesses face establishing effective work practices to evaluate OSS components. We find businesses have established processes for evaluating OSS components and communities that support more complex and nuanced considerations of the cost and risks of component adoption alongside matters such as licence compliance and functional requirements. We also found that the increasing pace and volume of software development within some businesses provides pressure to continue to evolve software evaluation processes.
Simon Butler 0001, Jonas Gamalielsson, Björn Lundell, Christoffer Brax, Anders Mattsson, Tomas Gustavsson, Jonas Feist, Bengt Kvarnström, Erik Lönroth
J. Syst. Softw.6
2021 On Company Contributions to Community Open Source Software Projects
abstract
The majority of contributions to community open source software (OSS) projects are made by practitioners acting on behalf of companies and other organisations. Previous research has addressed the motivations of both individuals and companies to engage with OSS projects. However, limited research has been undertaken that examines and explains the practical mechanisms or work practices used by companies and their developers to pursue their commercial and technical objectives when engaging with OSS projects. This research investigates the variety of work practices used in public communication channels by company contributors to engage with and contribute to eight community OSS projects. Through interviews with contributors to the eight projects we draw on their experiences and insights to explore the motivations to use particular methods of contribution. We find that companies utilise work practices for contributing to community projects which are congruent with the circumstances and their capabilities that support their short- and long-term needs. We also find that companies contribute to community OSS projects in ways that may not always be apparent from public sources, such as employing core project developers, making donations, and joining project steering committees in order to advance strategic interests. The factors influencing contributor work practices can be complex and are often dynamic arising from considerations such as company and project structure, as well as technical concerns and commercial strategies. The business context in which software created by the OSS project is deployed is also found to influence contributor work practices.
Simon Butler 0001, Jonas Gamalielsson, Björn Lundell, Christoffer Brax, Johan Sjöberg, Anders Mattsson, Tomas Gustavsson, Jonas Feist, Erik Lönroth
IEEE Trans. Software Eng.7
2020 Visualizing Inter-Team Coordination
abstract
As agile ways of working are implemented in larger settings, inter-team coordination becomes increasingly important. Some dependencies between teams can be identified in advance, but much of the dependencies in software development emerge as the system evolve. A way to identify, manage, assess, and evaluate the status of dependencies is to visualize dependencies between teams. New artifacts and routines for visualizing dependencies are suggested from the increasingly popular Scaled Agile Framework, SAFe. This multiple case study focuses on how inter-team coordination is visualized by providing a rich description of two years of implementation and tailoring of the boundary object called the program board at the (anonymized) organizations A-Gov and B-Bank. A total of 183 hours of observations and 14 interviews were used for triangulation purposes. The findings present the difficulties of keeping visualizations up to date. By inventing and tailoring the routines of managing the Program Board, the current situation of dependencies could be visualized and kept track of. The findings also indicate the importance of how dependencies are defined.
Tomas Gustavsson
EASE1
2020 Maintaining interoperability in open source software: A case study of the Apache PDFBox project
abstract
Software interoperability is commonly achieved through the implementation of standards for communication protocols or data representation formats. Standards documents are often complex, difficult to interpret, and may contain errors and inconsistencies, which can lead to differing interpretations and implementations that inhibit interoperability. Through a case study of two years of activity in the Apache PDFBox project we examine day-to-day decisions made concerning implementation of the PDF specifications and standards in a community open source software (OSS) project. Thematic analysis is used to identify semantic themes describing the context of observed decisions concerning interoperability. Fundamental decision types are identified including emulation of the behaviour of dominant implementations and the extent to which to implement the PDF standards. Many factors influencing the decisions are related to the sustainability of the project itself, while other influences result from decisions made by external actors, including the developers of dependencies of PDFBox. This article contributes a fine grained perspective of decision-making about software interoperability by contributors to a community OSS project. The study identifies how decisions made support the continuing technical relevance of the software, and factors that motivate and constrain project activity.
Simon Butler 0001, Jonas Gamalielsson, Björn Lundell, Christoffer Brax, Anders Mattsson, Tomas Gustavsson, Jonas Feist, Erik Lönroth
J. Syst. Softw.6
2015 On organisational influences in software standards and their open source implementations
abstract
It is widely acknowledged that standards implemented in open source software can reduce risks for lock-in, improve interoperability, and promote competition on the market. However, there is limited knowledge concerning the relationship between standards and their implementations in open source software. This paper reports from an investigation of organisational influences in software standards and open source software implementations of software standards. The study focuses on the RDFa standard and its implementation in the Drupal project. The overarching goal of the study is to establish organisational influences in software standards and their implementations in open source software. More specifically, our objective is to establish organisational influences in the RDFa standard and its implementation in the Drupal project. By conduct of a case study of the RDFa standard and its implementation in the Drupal project we investigate organisational influences in software standards and their implementations in open source software. Specifically, the case study involved quantitative analyses of issue tracker data for different issue trackers for W3C RDFa and the Drupal implementation of RDFa. The case study provides details on how and to what extent organisational influences occur in W3C RDFa and the Drupal implementation of RDFa, by specifically providing a characterisation of issues and results concerning contribution to issue raising and commenting, organisational involvement over time, and individual and organisational collaboration on issues. We find that widely deployed standards can benefit from contributions provided by a range of different individuals, organisations, and types of organisations either directly to a standardisation project or indirectly via an open source project implementing the standard. Further, we also find that open processes for standardisation adopted by W3C may also contribute to open source projects implementing specific standards.
Jonas Gamalielsson, Björn Lundell, Jonas Feist, Tomas Gustavsson, Fredric Landqvist
Inf. Softw. Technol.4
2014 On influences between software standards and their implementations in open source projects: Experiences from RDFa and its implementation in Drupal
abstract
It is widely acknowledged that standards implemented in open source software can reduce the risk for lock-in, improve interoperability, and promote competition on the market. However, there is limited knowledge concerning the relationship between standards and their implementations in open source software. This paper reports from an investigation of influences between software standards and open source software implementations of software standards. The study focuses on the RDFa standard and its implementation in the Drupal project. Specifically, issues in the W3C issue trackers for RDFa and the Drupal issue tracker for RDFa have been analysed. Findings show that there is clear evidence of reciprocal action between RDFa and its implementation in Drupal. The study contributes novel insights concerning effective processes for development and long-term maintenance of software standards and their implementations in open source projects.
Björn Lundell, Jonas Gamalielsson, Alexander Grahn, Jonas Feist, Tomas Gustavsson, Henrik Strindberg
OpenSym5
2008 Image analysis and CADx system for mucosal lesions
abstract
A computer aided diagnosis (CADx) system for oral mucosal lesions has been developed using clinical cases from India as training examples. The investigated classifiers were support vector machine (SVM) and Bayes point machine (BPM), and the task was to discriminate potentially precancerous lesions from non-precancerous lesions. The discriminating features consisted of color differences and lesionspsila shape properties. The overall classification accuracy was 85% (29 out of 34) for both SVM and BPM classifiers.
Artur Chodorowski, Chitta R. Choudhury, Tomas Gustavsson
BIBE3
2006 Time-Lapse Microscopy and Classification of in Vitro Cell Migration Using Hidden Markov Modeling
abstract
This paper describes a system for in vitro cell migration analysis. Adult neural stem/progenitor cells are studied using time-lapse microscopy and thereafter stained immunohistochemically to find and distinguish between undifferentiated glial progenitor cells and cells having differentiated into type-1 or type-2 astrocytes. The cells are automatically segmented and tracked throughout the time-lapse sequence. The evaluation showed that 88% of the cells were correctly segmented and tracked by the automatic system. Upon characterization of the cell migration by hidden Markov modeling, it was found that the motion of glial progenitor cells was random 2/3 of the time, while the type-2 astrocytes showed a directed movement 2/3 of the time. This finding indicates possibilities for cell-type specific identification and cell sorting of live cells based on specific movement patterns in individual cell populations, which will have valuable applications in neurobiological research
Karin Althoff, Johan Degerman, Carolina Wählby, Thorleif Thorlin, Jonas Faijerson, Peter S. Eriksson, Tomas Gustavsson
ICASSP (5)7
2004 Deformable spatio-temporal shape models: extending active shape models to 2D+time
Ghassan Hamarneh, Tomas Gustavsson
Image Vis. Comput.2
2001 Deformable Spatio-Temporal Shape Models: Extending ASM to 2D+Time
abstract
This paper extends 2D Active Shape Models to 2D+time by presenting a method for modelling and segmenting spatio-temporal shapes (ST-shapes). The modelling part consists of constructing a statistical model of ST-shape parameters. The model obtained describes the principal modes of variation of the ST-shape in addition to certain constraints on the allowed variations. An active approach is used in segmentation; an initial ST-shape is deformed to better fit the data and the optimal proposed deformation is calculated using dynamic programming. The results presented show the proposed method detecting ST-shapes in a variety of synthetic noisy data. Preliminary results on real data are also reported. 1
Ghassan Hamarneh, Tomas Gustavsson
BMVC2
2000 Active contour models: application to oral lesion detection in color images
abstract
This paper presents the application of active contour models (Snakes) for the segmentation of oral lesions in medical color images acquired from the visual part of the light spectrum. The aim is to assist the clinical expert in locating potentially cancerous cases for further analysis (e.g. classification of cancerous vs. non-cancerous lesions). In order to apply the conventional Snake formulation, color images were converted into single-band images. A number of different single-bands were evaluated including those resulting from the original and normalized RGB, perceptual HSI space, I/sub 1/I/sub 2/I/sub 3/, and the Fisher discriminant function. Examples of Snake segmentation results of oral lesions are presented.
Ghassan Hamarneh, Artur Chodorowski, Tomas Gustavsson
SMC3
2000 Statistically constrained snake deformations
abstract
The authors present a method for constraining the deformations of Snakes (active contour models) when segmenting a known class of objects. The method we propose is similar to both active shape models (ASM) but without the landmark identification and correspondence requirement, and to active contour models (ACM), but armed with a priori information about shape variation. Rather than representing the object boundary by spatial landmarks in a point-by-point fashion, we employ a frequency based boundary representation. In this way, the principal component analysis (PCA), which is central to ASM, is applied to a set of frequency-domain shape descriptors, removing the need for the difficult determination of spatial landmarks. Given a training set of representative images of the object of interest, we extract an average object shape along with a set of significant shape variation modes, explaining most of the shape variation in the training set. Armed with this a priori model of shape variation, we find the boundaries in unknown images by placing an initial ACM and allowing it to deform only according to the examined shape variations. The described methodology was applied to a set of 105 echocardiographic images for locating the left ventricular boundary. The results were particularly encouraging in clinically difficult cases where the ventricular boundary was partly occluded by noise.
Ghassan Hamarneh, Tomas Gustavsson
SMC2
2000 A Multiscale Dynamic Programming Procedure for Boundary Detection in Ultrasound Artery Images
abstract
Ultrasonic measurements of human carotid and femoral artery walls are conventionally obtained by manually tracing interfaces between tissue layers. The drawbacks of this method are the interobserver variability and inefficiency. In this paper, we present a new automated method which reduces these problems. By applying a multiscale dynamic programming (DP) algorithm, approximate vessel wall positions are first estimated in a coarse-scale image, which then guide the detection of the boundaries in a fine-scale image. In both cases, DP is used for finding a global optimum for a cost function. The cost function is a weighted sum of terms, in fuzzy expression forms, representing image features and geometrical characteristics of the vessel interfaces. The weights are adjusted by a training procedure using human expert tracings. Operator interventions, if needed, also take effect under the framework of global optimality. This reduces the amount of human intervention and, hence, variability due to subjectiveness. By incorporating human knowledge and experience, the algorithm becomes more robust. A thorough evaluation of the method in the clinical environment shows that interobserver variability is evidently decreased and so is the overall analysis time. We conclude that the automated procedure can replace the manual procedure and leads to an improved performance.
Quan Liang, Inger Wendelhag, John Wikstrand, Tomas Gustavsson
IEEE Trans. Medical Imaging4
1998 IsoIntensity Directional Smoothing for Edge-Preserving Noise Reduction
abstract
Isointensity directional smoothing is a novel edge-preserving smoothing method. By fitting a polynomial hypersurface to the local intensity, isointensity bands (isobands) are derived which approximately parallel an edge when the centre pixel is close to the edge. Pixels in the isoband passing through the centre are assigned higher weights, while those in other isobands are assigned lower weights according to a decaying function of the estimated intensity distance between the pixel and the centre. The weighted average of the pixel values is used as the smoothed value at the centre. The proposed method has a strong smoothing effect while causes little blurring of the edge, and the preserved edge has a good formation. The filter also performs well in intensity slope area. Experiments were carried on synthetic and real images. The results showed that the proposed filter has better performance than some well known edge-preserving filters compared in this work.
Quan Liang, Tomas Gustavsson
ICIP (2)2