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Anthony Maeder

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Federico Pecora

Örebro University

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Mersin University

Hubertus Vrijhoef

Mohamed Gamal Abdelmonem

University of York

Philips Electronics

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Papers by Anthony Maeder

Monitoring falls in elderly people: Lessons from a community-based project

by Habibollah Pirnejad and Anthony Maeder

Objectives. This paper describes an evaluation of a community-based fall-detection project using ... more Objectives. This paper describes an evaluation of a community-based fall-detection project using smart phone based tri-axial accelerometry to identify factors that affect adoption and use of such technology by elderly people. Methods. A mixed methods study using questionnaires and semi-structured interviews was conducted to evaluate attitudes of the elderly people participating, as well as project stakeholders involved in the project. Information registered in a web-based fall management system was analyzed both qualitatively and quantitatively, using an adapted version of Unified Theory of Acceptance and Use of Technology (UTAUT). Results. Adoption rate was 61.7% and attrition rate was 57%, the most common reasons for attrition being health deterioration (50%) and problems with the device and the network (26.2%). Conclusion. We identified a number of challenges that affected the success of this project, including problems with the software, usability issues with the device, coverage of the network, training of participants, and inadequacy of providing participants with a strong sense of safety and security.

Dattakumar, A, Gray, K., Maeder, A., Noble, D., Borda, A., Gasko, H., Jury, S., Schulz, T. (2013). A Unified Approach for the Evaluation of Telehealth Implementations in Australia: A White Paper. Institute for a Broadband Enabled Society (IBES), University of Melbourne.

by Ann Borda and Anthony Maeder

ISBN 978 0 7340 4865 3

Health Informatics and E-health Curriculum for Clinical Health Profession Degrees

Studies in health technology and informatics, 2015

The project reported in this paper models a new approach to making health informatics and e-healt... more The project reported in this paper models a new approach to making health informatics and e-health education widely available to students in a range of Australian clinical health profession degrees. The development of a Masters level subject uses design-based research to apply educational quality assurance practices which are consistent with university qualification frameworks, and with clinical health profession education standards; at the same time it gives recognition to health informatics as a specialised profession in its own right. The paper presents details of (a) design with reference to the Australian Qualifications Framework and CHIA competencies, (b) peer review within a three-university teaching team, (c) external review by experts from the professions, (d) cross-institutional interprofessional online learning, (e) methods for evaluating student learning experiences and outcomes, and (f) mechanisms for making the curriculum openly available to interested parties. The pro...

Building Data Synopses Within a Known Maximum Error Bound

by David Hansen and Anthony Maeder

Lecture Notes in Computer Science, 2007

The constructions of Haar wavelet synopses for large data sets have proven to be useful tools for... more The constructions of Haar wavelet synopses for large data sets have proven to be useful tools for data approximation. Recently, research on constructing wavelet synopses with a guaranteed maximum error has gained attention. Two relevant problems have been proposed: One is the size bounded problem that requires the construction of a synopsis of a given size to minimize the maximum error. Another is the error bounded problem that requires a minimum sized synopsis be built to satisfy a given error bound. The optimum algorithms for these two problems take O(N 2 ) time complexity. In this paper, we provide new algorithms for building error-bounded synopses. We first provide several property-based pruning techniques, which can greatly improve the performance of optimal error bounded synopses construction. We then demonstrate the efficiencies and effectiveness of our techniques through extensive experiments.

A New Approach for Error Resilience in Video Transmission Using ECC

Lecture Notes in Computer Science, 2003

Due to the vulnerability to errors of encoded video bitstream using current video coding standard... more Due to the vulnerability to errors of encoded video bitstream using current video coding standards, it is necessary to enhance the robustness of an encoded video bitstream for realizing decent video communication in error prone environment – especially in mobile or wireless situations. Though in some standards, some error-resilient video coding and error concealment tools have been introduced, video transmission

Medical Image Watermarking for Multiple Modalities

34th Applied Imagery and Pattern Recognition Workshop (AIPR'05), 2005

Transfer of digital medical images between multiple parties requires the assurance of image ident... more Transfer of digital medical images between multiple parties requires the assurance of image identity and integrity, which can be achieved through image watermarking. This raises concerns for loss in viewer performance due to degradation of image quality. Here we describe an approach to ensure that impact on the image quality is well below the threshold of visual perceptibility. The principles on which this approach rests are the choice of a suitably light payload, and the use of different watermarking methods and parameters for different medical image types. We provide examples of this approach applied to MR, CT and CR images

An automatic image quality assessment technique incorporating higher level perceptual factors

Proceedings 1998 International Conference on Image Processing. ICIP98 (Cat. No.98CB36269), 1998

We present an objective image quality assessment technique which is based on the properties of th... more We present an objective image quality assessment technique which is based on the properties of the human visual system (HVS). It consists of two major components: an early vision model (multi-channel and designed speci cally for complex natural images), and a visual attention model which indicates regions of interest in a scene through the use of Importance Maps. Visible errors are then weighted, depending on the perceptual importance of the region in which they occur. We show that this technique produces a high correlation with subjective test data (0.93), compared to only 0.65 for PSNR. This technique is particularly useful for images coded with spatially varying quality.

A Visual Attention Approach to Personal Identification

This paper describes the use of visual attention charac- teristics, monitored by gaze tracking du... more This paper describes the use of visual attention charac- teristics, monitored by gaze tracking during presentation of a known visual scene to a viewer, as a biometric for dis- tinguishing between individual viewers. The positions and sequences of gaze locations during viewing may be deter- mined by overt (conscious) or covert (sub-conscious) view- ing behaviour. Methods to quantify the spatial

Comparison of Popular Non-Rigid Image Registration Techniques and a New Hybrid Mutual Information-Based Fluid Algorithm

Recently there has emerged a need to compute mul- timodal non-rigid registrations in a lot of cli... more Recently there has emerged a need to compute mul- timodal non-rigid registrations in a lot of clinical ap- plications. To date, the viscous fluid algorithm is per- haps the most adept method at recovering large local mis- registrations that exist between two images. However, this model can only be used on images from the same modal- ity as it assumes

Achieving greater consistency in telehealth project evaluations to improve organisational learning

by Anthony Maeder and Nathan Poultney

Studies in health technology and informatics, 2015

Telehealth pilot projects and trial implementations are numerous but are often not fully evaluate... more Telehealth pilot projects and trial implementations are numerous but are often not fully evaluated, preventing construction of a sound evidence base and so limiting their adoption. We describe the need for a generic Telehealth project evaluation framework, within which evaluation is undertaken based on existing health systems performance indicators, using appropriately chosen measures. We provide two case studies explaining how this approach could be applied, in Australian and Canadian settings. It is argued that this framework type of approach to evaluation offers better potential for incorporating the learnings from resultant evaluations into business decisions by "learning organisations", through alignment with organisational performance considerations.

Examining an Australian physical activity and nutrition intervention using RE-AIM

by Anthony Maeder, Gregory Kolt, Kerry Mummery, and Corneel Vandelanotte

Health promotion international, Jan 25, 2015

Translating evidence-based interventions into community practice is vital to health promotion. Th... more Translating evidence-based interventions into community practice is vital to health promotion. This study used the RE-AIM framework to evaluate the larger dissemination of the ManUp intervention, an intervention which utilized interactive web-based technologies to improve the physical activity and nutrition behaviors of residents in Central Queensland, Australia. Data were collected for each RE-AIM measure (Reach, Effectiveness, Adoption, Implementation, Maintenance) using (i) computer-assisted telephone interview survey (N = 312) with adults (18 years and over) from Central Queensland, (ii) interviews with key stakeholders from local organizations (n = 12) and (iii) examination of project-related statistics and findings. In terms of Reach, 47% of participants were aware of the intervention; Effectiveness, there were no significant differences between physical activity and healthy nutrition levels in those aware and unaware; Adoption, 73 participants registered for the intervention ...

Assessing user engagement in a health promotion website using social networking

by Gregory Kolt, Anthony Maeder, Trevor N Savage, and Corneel Vandelanotte

Studies in health technology and informatics, 2014

Remote provision of supportive mechanisms for preventive health is a fast-growing area in eHealth... more Remote provision of supportive mechanisms for preventive health is a fast-growing area in eHealth. Web-based interventions have been suggested as an effective way to increase adoption and maintenance of healthy lifestyle behaviours. This paper describes results obtained in the "Walk 2.0" trial to promote physical activity through a self-managed walking programme, using a social networking website that provided an online collaborative environment. Engagement of participants with the website was assessed by monitoring usage of the individual social networking functions (e.g. status post). The results demonstrate that users generally preferred contributing non-interactive public posts of information concerned with their individual physical activity levels, and more occasionally communicating privately to friends. Further analysis of topics within posts was done by classifying word usage frequencies. Results indicated that the dominant topics are well aligned with the social e...

Electronic medical record information system for patient consultations in Chinese medicine

by Athula Ginige and Anthony Maeder

Studies in health technology and informatics, 2011

Currently there are no widely used systems to electronically record individual patient consultati... more Currently there are no widely used systems to electronically record individual patient consultations with Traditional Chinese Medicine (TCM) practitioners. As TCM practice differs significantly from western medicine both in diagnosis and treatment, using information systems created for western medicine is not suitable. There is a need for information systems developed specifically for TCM practitioners to manage patient consultation and treatments. Such system should be designed to facilitate safe and effective practice by providing decision support, utilising existing knowledge such as known herb-drug interactions to signal safety risks. Utilising current and developing standards and vocabularies such as those developed by the World Health Organisation (WHO) is important to facilitate interoperability with other systems. To facilitate continued growth in consumer demand, this type of system should be compatible with the needs of the individual electronic health records and other me...

Managing RBAC states with transitive relations

Proceedings of the 2nd ACM symposium on Information, computer and communications security - ASIACCS '07, 2007

In this paper, we study the maintenance of role-based access control (RBAC) models in database en... more In this paper, we study the maintenance of role-based access control (RBAC) models in database environments using transitive closure relations. In particular, the algorithms that express and remove redundancy from a component, a RBAC state, and from conflict constraints. The transitive closure relations on a RBAC state specify the reachability among user groups, roles and from user groups to roles. These relations can assist the process of authorization and make some queries easier to answer. Paper shows that the transitive closure relations on a RBAC model can be used to manage and maintain the model's dynamic changes in a simple and efficient way. In this paper, we firstly show that the transitive closure relations are natural byproducts when formulating RBAC components. We then adapt the conventional RBAC model to accord the inherent reachability of a RBAC model. We show that the use of transitive closure relations as the auxiliary relations for the maintenance of a RBAC state alleviates the process of query evaluation, removing redundancy and the description of hierarchies. Thirdly, in the presence of conflict constraints, we explain how conflicts can be expressed, checked and evaluated under the existence of TC relations, in addition to the removal of conflicts redundancy and finding inferred conflicts. Lastly, we briefly discuss the first-order maintenance operations.

Privacy-Preserving Fuzzy Matching Using a Public Reference Table

by David Hansen and Anthony Maeder

Studies in Computational Intelligence, 2009

Page 1. Privacy-Preserving Fuzzy Matching Using a Public Reference Table Chaoyi Pang 1 , Lifang G... more

<title>Perceptually based quantization technique for MPEG encoding</title>

Human Vision and Electronic Imaging III, 1998

We present a technique for controlling the adaptive quantization process in an MPEG encoder, whic... more We present a technique for controlling the adaptive quantization process in an MPEG encoder, which improves upon the commonly used Test Model 5 (TM5) rate controller. The method combines both a spatial masking model and a technique for automatically determining the visually important areas in a scene. The spatial masking model has been designed with consideration of the structure of compressed natural images. It takes into account the di erent levels of distortion that are tolerable by viewers in di erent parts of a picture by segmenting the scene into at, edge, and textured regions and quantizing these regions di erently. The visually important areas are represented by Importance Maps. These maps are generated by combining factors known to in uence human visual attention and eye movements. Lower quantization is assigned to visually important regions, while areas classi ed as being of low visual importance are more harshly quantized. Results indicate a subjective improvement in picture quality, in comparison to the TM5 method. Less ringing occurs at edges, and the visually important areas of a picture are more accurately coded. This is particularly noticeable at low bit rates. The technique is computationally e cient and exible, and can easily be extended to speci c applications.

Mobility assessment using simulated Artificial Human Vision

by Anthony Maeder and Jason Dowling

Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition, 2005, 2005

has focused on providing visually meaningful information to the blind through electrical stimulat... more has focused on providing visually meaningful information to the blind through electrical stimulation of a visual system component. This paper reports on the use of a programmable PDA-based AHV simulator which can be used by normally sighted participants. Using three different display types, mobility performance on an indoor artificial mobility course was assessed using Percentage of Preferred Walking Speed (PPWS) and mobility errors. A looming obstacle alert display was not found to assist with mobility performance. Mobility performance increased as participants learned to use the simulation effectively. Posture, head movements and gait were affected by use of the simulation.

Improving the Use, Analysis and Integration of Patient Health Data

Lecture Notes in Computer Science, 2008

Y. Ishikawa et al. (Eds.): APWeb 2008 Workshops, LNCS 4977, pp. 7484, 2008. © Springer-Verlag Be... more

A Comparison of DCT and DWT Block Based Watermarking on Medical Image Quality

by Jason Dowling and Anthony Maeder

Lecture Notes in Computer Science, 2008

Hiding watermark information in medical image data files is one method of enhancing security and ... more Hiding watermark information in medical image data files is one method of enhancing security and protecting patient privacy. However the research area of medical image watermarking has not been particularly active, partly due to concerns that any distortion could effect the diagnostic value of the medical image. These concerns can be address by ensuring that any image changes are kept below visual perception thresholds. In this paper the effects of image watermarking and common image manipulations are measured using the Peak Signal-to-Noise Ratio (PSNR), Structural Similarity Measure (SSIM) and Steerable Visual Difference Predictor (SVDP) numerical metrics. Two methods of block based watermarking are compared: the Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT). To ensure a fair comparison a 128-pixel block size is used which allows an identical amount of information to be embedded for each method (3072 bits multiplied by embedding strength). The results suggest that although the two methods are similar, the DCT method is preferable if localization of changes is required. If localization is not required the DWT method is supported.

<title>Visual quality assessment of watermarked medical images</title>

by Anthony Maeder and Jason Dowling

Medical Imaging 2007: Image Perception, Observer Performance, and Technology Assessment, 2007

Increasing transmission of medical images across multiple user systems raises concerns for image ... more Increasing transmission of medical images across multiple user systems raises concerns for image security. Hiding watermark information in medical image data files is one solution for enhancing security and privacy protection of data. Medical image watermarking however is not a widely studied area, due partially to speculations on loss in viewer performance caused by degradation of image information. Such concerns are addressed if the amount of information lost due to watermarking can be kept at minimal levels and below visual perception thresholds. This paper describes experiments where three alternative visual quality metrics were used to assess the degradation caused by watermarking medical images. Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) medical images were watermarked using different methods: Block based Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT) with various embedding strengths. The visual degradation of each watermarking parameter setting was assessed using Peak Signal-to-Noise Ratio (PSNR), Structural Similarity Measure (SSIM) and Steerable Visual Difference Predictor (SVDP) numerical metrics. The suitability of each of the three numerical metrics for medical image watermarking visual quality assessment is noted. In addition, subjective test results from human observers are used to suggest visual degradation thresholds.

Monitoring falls in elderly people: Lessons from a community-based project

by Habibollah Pirnejad and Anthony Maeder

Objectives. This paper describes an evaluation of a community-based fall-detection project using ... more Objectives. This paper describes an evaluation of a community-based fall-detection project using smart phone based tri-axial accelerometry to identify factors that affect adoption and use of such technology by elderly people. Methods. A mixed methods study using questionnaires and semi-structured interviews was conducted to evaluate attitudes of the elderly people participating, as well as project stakeholders involved in the project. Information registered in a web-based fall management system was analyzed both qualitatively and quantitatively, using an adapted version of Unified Theory of Acceptance and Use of Technology (UTAUT). Results. Adoption rate was 61.7% and attrition rate was 57%, the most common reasons for attrition being health deterioration (50%) and problems with the device and the network (26.2%). Conclusion. We identified a number of challenges that affected the success of this project, including problems with the software, usability issues with the device, coverage of the network, training of participants, and inadequacy of providing participants with a strong sense of safety and security.

Dattakumar, A, Gray, K., Maeder, A., Noble, D., Borda, A., Gasko, H., Jury, S., Schulz, T. (2013). A Unified Approach for the Evaluation of Telehealth Implementations in Australia: A White Paper. Institute for a Broadband Enabled Society (IBES), University of Melbourne.

by Ann Borda and Anthony Maeder

ISBN 978 0 7340 4865 3

Health Informatics and E-health Curriculum for Clinical Health Profession Degrees

Studies in health technology and informatics, 2015

The project reported in this paper models a new approach to making health informatics and e-healt... more The project reported in this paper models a new approach to making health informatics and e-health education widely available to students in a range of Australian clinical health profession degrees. The development of a Masters level subject uses design-based research to apply educational quality assurance practices which are consistent with university qualification frameworks, and with clinical health profession education standards; at the same time it gives recognition to health informatics as a specialised profession in its own right. The paper presents details of (a) design with reference to the Australian Qualifications Framework and CHIA competencies, (b) peer review within a three-university teaching team, (c) external review by experts from the professions, (d) cross-institutional interprofessional online learning, (e) methods for evaluating student learning experiences and outcomes, and (f) mechanisms for making the curriculum openly available to interested parties. The pro...

Building Data Synopses Within a Known Maximum Error Bound

by David Hansen and Anthony Maeder

Lecture Notes in Computer Science, 2007

The constructions of Haar wavelet synopses for large data sets have proven to be useful tools for... more The constructions of Haar wavelet synopses for large data sets have proven to be useful tools for data approximation. Recently, research on constructing wavelet synopses with a guaranteed maximum error has gained attention. Two relevant problems have been proposed: One is the size bounded problem that requires the construction of a synopsis of a given size to minimize the maximum error. Another is the error bounded problem that requires a minimum sized synopsis be built to satisfy a given error bound. The optimum algorithms for these two problems take O(N 2 ) time complexity. In this paper, we provide new algorithms for building error-bounded synopses. We first provide several property-based pruning techniques, which can greatly improve the performance of optimal error bounded synopses construction. We then demonstrate the efficiencies and effectiveness of our techniques through extensive experiments.

A New Approach for Error Resilience in Video Transmission Using ECC

Lecture Notes in Computer Science, 2003

Due to the vulnerability to errors of encoded video bitstream using current video coding standard... more Due to the vulnerability to errors of encoded video bitstream using current video coding standards, it is necessary to enhance the robustness of an encoded video bitstream for realizing decent video communication in error prone environment – especially in mobile or wireless situations. Though in some standards, some error-resilient video coding and error concealment tools have been introduced, video transmission

Medical Image Watermarking for Multiple Modalities

34th Applied Imagery and Pattern Recognition Workshop (AIPR'05), 2005

Transfer of digital medical images between multiple parties requires the assurance of image ident... more Transfer of digital medical images between multiple parties requires the assurance of image identity and integrity, which can be achieved through image watermarking. This raises concerns for loss in viewer performance due to degradation of image quality. Here we describe an approach to ensure that impact on the image quality is well below the threshold of visual perceptibility. The principles on which this approach rests are the choice of a suitably light payload, and the use of different watermarking methods and parameters for different medical image types. We provide examples of this approach applied to MR, CT and CR images

An automatic image quality assessment technique incorporating higher level perceptual factors

Proceedings 1998 International Conference on Image Processing. ICIP98 (Cat. No.98CB36269), 1998

We present an objective image quality assessment technique which is based on the properties of th... more We present an objective image quality assessment technique which is based on the properties of the human visual system (HVS). It consists of two major components: an early vision model (multi-channel and designed speci cally for complex natural images), and a visual attention model which indicates regions of interest in a scene through the use of Importance Maps. Visible errors are then weighted, depending on the perceptual importance of the region in which they occur. We show that this technique produces a high correlation with subjective test data (0.93), compared to only 0.65 for PSNR. This technique is particularly useful for images coded with spatially varying quality.

A Visual Attention Approach to Personal Identification

This paper describes the use of visual attention charac- teristics, monitored by gaze tracking du... more This paper describes the use of visual attention charac- teristics, monitored by gaze tracking during presentation of a known visual scene to a viewer, as a biometric for dis- tinguishing between individual viewers. The positions and sequences of gaze locations during viewing may be deter- mined by overt (conscious) or covert (sub-conscious) view- ing behaviour. Methods to quantify the spatial

Comparison of Popular Non-Rigid Image Registration Techniques and a New Hybrid Mutual Information-Based Fluid Algorithm

Recently there has emerged a need to compute mul- timodal non-rigid registrations in a lot of cli... more Recently there has emerged a need to compute mul- timodal non-rigid registrations in a lot of clinical ap- plications. To date, the viscous fluid algorithm is per- haps the most adept method at recovering large local mis- registrations that exist between two images. However, this model can only be used on images from the same modal- ity as it assumes

Achieving greater consistency in telehealth project evaluations to improve organisational learning

by Anthony Maeder and Nathan Poultney

Studies in health technology and informatics, 2015

Telehealth pilot projects and trial implementations are numerous but are often not fully evaluate... more Telehealth pilot projects and trial implementations are numerous but are often not fully evaluated, preventing construction of a sound evidence base and so limiting their adoption. We describe the need for a generic Telehealth project evaluation framework, within which evaluation is undertaken based on existing health systems performance indicators, using appropriately chosen measures. We provide two case studies explaining how this approach could be applied, in Australian and Canadian settings. It is argued that this framework type of approach to evaluation offers better potential for incorporating the learnings from resultant evaluations into business decisions by "learning organisations", through alignment with organisational performance considerations.

Examining an Australian physical activity and nutrition intervention using RE-AIM

by Anthony Maeder, Gregory Kolt, Kerry Mummery, and Corneel Vandelanotte

Health promotion international, Jan 25, 2015

Translating evidence-based interventions into community practice is vital to health promotion. Th... more Translating evidence-based interventions into community practice is vital to health promotion. This study used the RE-AIM framework to evaluate the larger dissemination of the ManUp intervention, an intervention which utilized interactive web-based technologies to improve the physical activity and nutrition behaviors of residents in Central Queensland, Australia. Data were collected for each RE-AIM measure (Reach, Effectiveness, Adoption, Implementation, Maintenance) using (i) computer-assisted telephone interview survey (N = 312) with adults (18 years and over) from Central Queensland, (ii) interviews with key stakeholders from local organizations (n = 12) and (iii) examination of project-related statistics and findings. In terms of Reach, 47% of participants were aware of the intervention; Effectiveness, there were no significant differences between physical activity and healthy nutrition levels in those aware and unaware; Adoption, 73 participants registered for the intervention ...

Assessing user engagement in a health promotion website using social networking

by Gregory Kolt, Anthony Maeder, Trevor N Savage, and Corneel Vandelanotte

Studies in health technology and informatics, 2014

Remote provision of supportive mechanisms for preventive health is a fast-growing area in eHealth... more Remote provision of supportive mechanisms for preventive health is a fast-growing area in eHealth. Web-based interventions have been suggested as an effective way to increase adoption and maintenance of healthy lifestyle behaviours. This paper describes results obtained in the "Walk 2.0" trial to promote physical activity through a self-managed walking programme, using a social networking website that provided an online collaborative environment. Engagement of participants with the website was assessed by monitoring usage of the individual social networking functions (e.g. status post). The results demonstrate that users generally preferred contributing non-interactive public posts of information concerned with their individual physical activity levels, and more occasionally communicating privately to friends. Further analysis of topics within posts was done by classifying word usage frequencies. Results indicated that the dominant topics are well aligned with the social e...

Electronic medical record information system for patient consultations in Chinese medicine

by Athula Ginige and Anthony Maeder

Studies in health technology and informatics, 2011

Currently there are no widely used systems to electronically record individual patient consultati... more Currently there are no widely used systems to electronically record individual patient consultations with Traditional Chinese Medicine (TCM) practitioners. As TCM practice differs significantly from western medicine both in diagnosis and treatment, using information systems created for western medicine is not suitable. There is a need for information systems developed specifically for TCM practitioners to manage patient consultation and treatments. Such system should be designed to facilitate safe and effective practice by providing decision support, utilising existing knowledge such as known herb-drug interactions to signal safety risks. Utilising current and developing standards and vocabularies such as those developed by the World Health Organisation (WHO) is important to facilitate interoperability with other systems. To facilitate continued growth in consumer demand, this type of system should be compatible with the needs of the individual electronic health records and other me...

Managing RBAC states with transitive relations

Proceedings of the 2nd ACM symposium on Information, computer and communications security - ASIACCS '07, 2007

In this paper, we study the maintenance of role-based access control (RBAC) models in database en... more In this paper, we study the maintenance of role-based access control (RBAC) models in database environments using transitive closure relations. In particular, the algorithms that express and remove redundancy from a component, a RBAC state, and from conflict constraints. The transitive closure relations on a RBAC state specify the reachability among user groups, roles and from user groups to roles. These relations can assist the process of authorization and make some queries easier to answer. Paper shows that the transitive closure relations on a RBAC model can be used to manage and maintain the model's dynamic changes in a simple and efficient way. In this paper, we firstly show that the transitive closure relations are natural byproducts when formulating RBAC components. We then adapt the conventional RBAC model to accord the inherent reachability of a RBAC model. We show that the use of transitive closure relations as the auxiliary relations for the maintenance of a RBAC state alleviates the process of query evaluation, removing redundancy and the description of hierarchies. Thirdly, in the presence of conflict constraints, we explain how conflicts can be expressed, checked and evaluated under the existence of TC relations, in addition to the removal of conflicts redundancy and finding inferred conflicts. Lastly, we briefly discuss the first-order maintenance operations.

Privacy-Preserving Fuzzy Matching Using a Public Reference Table

by David Hansen and Anthony Maeder

Studies in Computational Intelligence, 2009

Page 1. Privacy-Preserving Fuzzy Matching Using a Public Reference Table Chaoyi Pang 1 , Lifang G... more

<title>Perceptually based quantization technique for MPEG encoding</title>

Human Vision and Electronic Imaging III, 1998

We present a technique for controlling the adaptive quantization process in an MPEG encoder, whic... more We present a technique for controlling the adaptive quantization process in an MPEG encoder, which improves upon the commonly used Test Model 5 (TM5) rate controller. The method combines both a spatial masking model and a technique for automatically determining the visually important areas in a scene. The spatial masking model has been designed with consideration of the structure of compressed natural images. It takes into account the di erent levels of distortion that are tolerable by viewers in di erent parts of a picture by segmenting the scene into at, edge, and textured regions and quantizing these regions di erently. The visually important areas are represented by Importance Maps. These maps are generated by combining factors known to in uence human visual attention and eye movements. Lower quantization is assigned to visually important regions, while areas classi ed as being of low visual importance are more harshly quantized. Results indicate a subjective improvement in picture quality, in comparison to the TM5 method. Less ringing occurs at edges, and the visually important areas of a picture are more accurately coded. This is particularly noticeable at low bit rates. The technique is computationally e cient and exible, and can easily be extended to speci c applications.

Mobility assessment using simulated Artificial Human Vision

by Anthony Maeder and Jason Dowling

Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition, 2005, 2005

has focused on providing visually meaningful information to the blind through electrical stimulat... more has focused on providing visually meaningful information to the blind through electrical stimulation of a visual system component. This paper reports on the use of a programmable PDA-based AHV simulator which can be used by normally sighted participants. Using three different display types, mobility performance on an indoor artificial mobility course was assessed using Percentage of Preferred Walking Speed (PPWS) and mobility errors. A looming obstacle alert display was not found to assist with mobility performance. Mobility performance increased as participants learned to use the simulation effectively. Posture, head movements and gait were affected by use of the simulation.

Improving the Use, Analysis and Integration of Patient Health Data

Lecture Notes in Computer Science, 2008

Y. Ishikawa et al. (Eds.): APWeb 2008 Workshops, LNCS 4977, pp. 7484, 2008. © Springer-Verlag Be... more

A Comparison of DCT and DWT Block Based Watermarking on Medical Image Quality

by Jason Dowling and Anthony Maeder

Lecture Notes in Computer Science, 2008

Hiding watermark information in medical image data files is one method of enhancing security and ... more Hiding watermark information in medical image data files is one method of enhancing security and protecting patient privacy. However the research area of medical image watermarking has not been particularly active, partly due to concerns that any distortion could effect the diagnostic value of the medical image. These concerns can be address by ensuring that any image changes are kept below visual perception thresholds. In this paper the effects of image watermarking and common image manipulations are measured using the Peak Signal-to-Noise Ratio (PSNR), Structural Similarity Measure (SSIM) and Steerable Visual Difference Predictor (SVDP) numerical metrics. Two methods of block based watermarking are compared: the Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT). To ensure a fair comparison a 128-pixel block size is used which allows an identical amount of information to be embedded for each method (3072 bits multiplied by embedding strength). The results suggest that although the two methods are similar, the DCT method is preferable if localization of changes is required. If localization is not required the DWT method is supported.

<title>Visual quality assessment of watermarked medical images</title>

by Anthony Maeder and Jason Dowling

Medical Imaging 2007: Image Perception, Observer Performance, and Technology Assessment, 2007

Increasing transmission of medical images across multiple user systems raises concerns for image ... more Increasing transmission of medical images across multiple user systems raises concerns for image security. Hiding watermark information in medical image data files is one solution for enhancing security and privacy protection of data. Medical image watermarking however is not a widely studied area, due partially to speculations on loss in viewer performance caused by degradation of image information. Such concerns are addressed if the amount of information lost due to watermarking can be kept at minimal levels and below visual perception thresholds. This paper describes experiments where three alternative visual quality metrics were used to assess the degradation caused by watermarking medical images. Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) medical images were watermarked using different methods: Block based Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT) with various embedding strengths. The visual degradation of each watermarking parameter setting was assessed using Peak Signal-to-Noise Ratio (PSNR), Structural Similarity Measure (SSIM) and Steerable Visual Difference Predictor (SVDP) numerical metrics. The suitability of each of the three numerical metrics for medical image watermarking visual quality assessment is noted. In addition, subjective test results from human observers are used to suggest visual degradation thresholds.