Papers by Manuel Menezes de Sequeira
Proceedings of the …, 1993
The modelling and simulation of distillation columns is mainly applied to plate columns and less ... more The modelling and simulation of distillation columns is mainly applied to plate columns and less to random packing columns.
Proc. 5th International …, Jan 1, 1999
This paper describes a traffic surveillance system as a particular case of the class of intellige... more This paper describes a traffic surveillance system as a particular case of the class of intelligent distributed dynamic-information systems (IDDIS). The Traffic Surveillance System is a vision-based FIPA compliant multi-agent system that uses the FIPA Agent Communication Language (ACL) and the FIPA Semantic Language (SL). The focus of the work is inter-agent communication and coordination. We have extended the SL expressiveness with respect to the representation of uncertainty and to the representation of ad hoc MPEG7 descriptions. We propose a transport encoding format more suitable for time-constrained systems than the original textual format proposed in the FIPA specifications. We show that, within the scope of the FIPA platform, the FIPA ACL is a communication language powerful enough to achieve multi-agent coordination through communication. This work also suggests that the FIPA platform is suitable for building surveillance based applications.
The consolidation of the Bologna process in HEI requires a swift production and communication of ... more The consolidation of the Bologna process in HEI requires a swift production and communication of a set of integrated performance indicators. These indicators will enable the generation of the necessary information to monitor the quality of the teaching and learning in all programmes offered at ISCTE-IUL. This implies the gathering of a large amount of data, as well as the integration of diverse source systems. Unless a reliable IT approach is used, this may well result in a highly complex, time-consuming, or even maybe an unfeasible task given the quality standards that the University aims to deliver to its students. The proposed IT approach, based on the development of a Data Warehouse and Business Intelligence application, will be used to produce a subset of the Bologna reports for the 2008/2009 academic year. Expected outcomes of this approach are diverse, including the reliability reinforcement of the provided analysis and information.
A implementação do quadro de referência ITIL (IT Infrastructure LibraryTM) no contexto académico ... more A implementação do quadro de referência ITIL (IT Infrastructure LibraryTM) no contexto académico é já uma realidade em alguns países, nomeadamente no Reino Unido e nos EUA. Este artigo apresenta a sua aplicação à gestão dos sistemas de informação e tecnologias da informação de uma universidade portuguesa: o ISCTE – Instituto Universitário de Lisboa (ISCTE-IUL).
O artigo descreve um projecto-piloto na área da gestão de configurações e de activos de serviço desenvolvido, no âmbito de um trabalho académico, em colaboração estreita com a Direcção de Serviços de Informática do ISCTE-IUL. Embora o artigo se foque fundamentalmente nos aspectos de implementação do processo referido, de acordo com as melhores práticas do ITIL, descreve também a componente de business intelligence do projecto-piloto. Esta componente consiste num sistema de reporte (reporting), assente na plataforma de business intelligence da Microsoft, destinado a colmatar a deficiente capacidade de reporte da ferramenta de gestão de activos actualmente em utilização na universidade.
In 1992, a joint committee between the International Organization for Standardization (ISO) and t... more In 1992, a joint committee between the International Organization for Standardization (ISO) and the Telecommunication Standardization Sector of the International Telecommunication Union (ITU-T) known as the Joint Photographic Experts Group (JPEG) Joint Photographic Experts Group (JPEG) issued a standard that was approved in 1994 as ISO/IEC 10918-1 or ITU-T Recommendation T.81. This standard received the name of Information technology – Digital compression and coding of continuous-tone still images requirements and guidelines but it is commonly known as the JPEG standard.
In 1982, the CCIR defined a standard for encoding interlaced analogue video signals in digital fo... more In 1982, the CCIR defined a standard for encoding interlaced analogue video signals in digital form mainly for studio applications. The current name of this standard is ITU-R BT.601 (ITU 1983). Following this standard, a video signal sampled at 13.5 MHz with a 4:2:2 sampling format (double the number of samples for the luminance component than for the two chrominance components) and quantized with 8 bits per component produces a raw bit rate of 216 Mbps. This rate can be reduced by removing the blanking intervals present in the interlaced analogue signal leading to a bit rate of 166 Mbps, which is still a figure far above the main capacity of usual transmission channels or storage devices.
In this paper we will describe a national perspective on the achievements of the Bologna Process ... more In this paper we will describe a national perspective on the achievements of the Bologna Process in Portugal regarding the academic years of 2006/2007 and 2007/2008, and detail the approach followed at the Lisbon University Institute (ISCTE-IUL). The main objective of the paper is to describe the joint initiative that has been developed at ISCTE-IUL to implement a Decision Support System (DSS) that will enable the collection, analysis and dissemination (through reporting) of the required performance indicators to render possible an automatic elaboration of these reports. The paper will focus on the requirements gathering phase of the decision support system designed to enable the automatic generation of Bologna reports. This DSS constitutes a research project and is being developed with the sponsorship of the Computer Center (DSI) and Quality Assurance and Evaluation Office (GAQE), integrated with the University’s information system Fénix (based on FénixEDU®).
This paper proposes Zás, a novel, flexible, and expressive authorization mechanism for Java. Zás ... more This paper proposes Zás, a novel, flexible, and expressive authorization mechanism for Java. Zás has been inspired by Ramnivas Laddad's proposal to modularize Java Authentication and Authorization Services (JAAS) using an Aspect-Oriented Programming (AOP) approach. Zás' aims are to be simultaneously very expressive, reusable, and easy to use and configure. Zás allows authorization services to be non-invasively added to existing code. It also cohabits with a wide range of authentication mechanisms. Zás uses Java 5 annotations to specify permission requirements to access controlled resources. These requirements may be changed directly during execution. They may also be calculated by client supplied permission classes before each access to the corresponding resource. These features, together with several mechanisms for permission propagation, expression of trust relationships, depth of access control, etc., make Zás, we believe, an interesting starting point for further research on the use of AOP for authorization.
This paper proposes Zás, a novel, flexible, and expressive authorization mechanism for Java. Zás ... more This paper proposes Zás, a novel, flexible, and expressive authorization mechanism for Java. Zás has been inspired by Ramnivas Laddad's proposal to modularize Java Authentication and Authorization Services (JAAS) using an Aspect-Oriented Programming (AOP) approach. Zás' aims are to be simultaneously very expressive, reusable, and easy to use and configure. Zás allows authorization services to be non-invasively added to existing code. It also cohabits with a wide range of authentication mechanisms. Zás uses Java 5 annotations to specify permission requirements to access controlled resources. These requirements may be changed directly during execution. They may also be calculated by client supplied permission classes before each access to the corresponding resource. These features, together with several mechanisms for permission propagation, expression of trust relationships, depth of access control, etc., make Zás, we believe, an interesting starting point for further research on the use of AOP for authorization.
We propose a new evaluation method for license-plate location algorithms. As a first step towards... more We propose a new evaluation method for license-plate location algorithms. As a first step towards a comparison of the algorithms described in the literature over the years, we have implemented some relevant algorithms with different approaches and compared them using the proposed evaluation method.
The software used for evaluation and a set of annotated evaluation images are both readily available, making the reproduction of the presented results possible. The availability of both software and an evaluation set allows the results presented in this paper to be used as benchmarks when developing plate location algorithms.
This paper describes a traffic surveillance system as a particular case of the class of intellige... more This paper describes a traffic surveillance system as a particular case of the class of intelligent distributed dynamic-information systems (IDDIS). The Traffic Surveillance System is a vision-based FIPA compliant multi-agent system that uses the FIPA Agent Communication Language (ACL) and the FIPA Semantic Language (SL). The focus of the work is inter-agent communication and coordination. We have extended the SL expressiveness with respect to the representation of uncertainty and to the representation of ad hoc MPEG7 descriptions. We propose a transport encoding format more suitable for time-constrained systems than the original textual format proposed in the FIPA specifications. We show that, within the scope of the FIPA platform, the FIPA ACL is a communication language powerful enough to achieve multi-agent coordination through communication. This work also suggests that the FIPA platform is suitable for building surveillance based applications.
This paper describes a new license-plate location algorithm using a sequential multistage approac... more This paper describes a new license-plate location algorithm using a sequential multistage approach, where each stage consists of a different sub-algorithm. All the proposed subalgorithms make use of morphological operations performed over both gray-scale and binary images. In order to ascertain the performance of the proposed algorithm, and to fairly compare it with license-plate location algorithms developed by other authors, a well-defined evaluation method is used. Results have shown that the proposed algorithm produces at least one accurate license-plate location hypothesis for 97.18% of 673 images acquired at a highway toll fence.
Classical video coding algorithms, based on low-level vision concepts, seem to be reaching a perf... more Classical video coding algorithms, based on low-level vision concepts, seem to be reaching a performance plateau. This sparkled research in new coding approaches based on mid-level vision notions. However, when evaluated using the three classical performance criteria, rate, distortion, and cost, the few new generation video codecs already developed do not seem to provide as large improvements over the classical ones as would be desirable.
This is due to the fact that a new fourth criterion, based on new user needs, has been overlooked: content access effort. The new user needs have also been recognized by MPEG-4, which intends to develop an audio-visual coding standard addressing new content based functionalities. MPEG-4 will also guarantee its own future evolution and extensibility through the use of a flexible syntax and the provision for programmable codecs.
This paper proposes an architecture for a four-criteria mid-level vision video codec that will be the basis for a future MPEG-4 proposal. The blocks of the codec and the interfaces between them are described. The main blocks of the codec, namely image and motion analysis, are discussed in detail and some possible solutions are proposed.
In the framework of moving image analysis for image coding, the time coherence of segmentation is... more In the framework of moving image analysis for image coding, the time coherence of segmentation is important for at least two reasons. In the first place, when the user is allowed to interact with the encoded scene, it must be possible, for instance, for him to select, zoom, rotate, or change any scene objects. This implies that objects must be identified uniquely in each of the images of the sequence in which they occur. Finally, segmentation coherence is important because it improves coding efficiency when time prediction is used.
This paper extends previous work on still image segmentation using split & merge to deal also with moving images. The technique proposed performs a time-recursive segmentation. Time recursion is introduced by using a region-growing like version of the original segmentation algorithm such that the previously segmented regions are projected into the current image. The results obtained show that the technique is a good candidate for image analysis in the framework of second-generation moving image coding.
Recognising the importance of partition or shape coding in the field of image and video coding, a... more Recognising the importance of partition or shape coding in the field of image and video coding, and the fact that a systematisation of the subject would simplify the comparison of partition coding techniques, this paper proposes a classification of partition types and partition representations into a taxonomy tree. The partition type level of the tree classifies the possible partition types that may have to be coded. The partition representation level classifies the possible representations for each partition type.
This paper also overviews the partition coding techniques which address the considered partition types and which use the identified partition representations. Emphasis is given to binary partition coding techniques proposed within the framework of MPEG-4.
In order to improve the performance of the classical pixel-based image coding techniques, new tec... more In order to improve the performance of the classical pixel-based image coding techniques, new technical approaches are deemed necessary. These approaches aim at a better understanding of the image content, in terms of regions, textures, etc., thus "healing the blindness" of the old schemes.
The new image coding approaches require the identification of regions or "objects", i.e., image segmentation. This process results in an image partition matrix, which includes contour information, and a set of parameters characterising each region according to a given set of image features.
The contour information represents an extremely important and sensitive information for the human visual system, being thus also of great importance in the image coding context.
This paper proposes a classification of partition and contour models according to a tree structure, in order to clearly identify the contour models to which contour coding techniques can be applied. It also proposes a lossless contour coding technique based on Freeman's chain codes.
Very low bitrate video coding became in the last years one of the most important areas of image c... more Very low bitrate video coding became in the last years one of the most important areas of image communication due to the identification of several very low bitrate applications such as mobile videotelephony, multimedia mail, electronic newspapers, entertainment, traffic control, and interactive data bases.
Since conventional video coding techniques are reaching a saturation point, a new generation of techniques, aiming at a deeper “understanding” of the image, is being studied. In this context, image analysis, particularly the identification of regions or objects in images (segmentation), is an important step in very low bitrate video coding, since it will lead to a better representation of images and consequently to an improvement of the encoded image quality (for a fixed bitrate).
This paper describes a segmentation algorithm based on split & merge and shortest spanning trees (SST). The image is first split according to a quad tree structure and then the resulting regions are merged, using the SST concept, in three steps: merge, elimination of small regions and control of the number of regions.
Results are presented for video sequences from studio and mobile videotelephony, which show the good properties of the algorithm for application in very low bitrate video coding schemes.
Video coding has been under intense scrutiny during the last years. The published international s... more Video coding has been under intense scrutiny during the last years. The published international standards rely on low-level vision concepts, thus being first-generation. Recently standardization started in second-generation video coding, supported on mid-level vision concepts such as objects.
This thesis presents new architectures for second-generation video codecs and some of the required analysis and coding tools.
The graph theoretic foundations of image analysis are presented and algorithms for generalized shortest spanning tree problems are proposed. In this light, it is shown that basic versions of several region-oriented segmentation algorithms address the same problem. Globalization of information is studied and shown to confer different properties to these algorithms, and to transform region merging in recursive shortest spanning tree segmentation (RSST). RSST algorithms attempting to minimize global approximation error and using affine region models are shown to be very effective. A knowledge-based segmentation algorithm for mobile videotelephony is proposed.
A new camera movement estimation algorithm is developed which is effective for image stabilization and scene cut detection. A camera movement compensation technique for first-generation codecs is also proposed.
A systematization of partition types and representations is performed with which partition coding tools are overviewed. A fast approximate closed cubic spline algorithm is developed with applications in partition coding.
Very low bit-rate video coding has recently become one of the most important areas of image commu... more Very low bit-rate video coding has recently become one of the most important areas of image communication and a large variety of applications have already been identified. Since conventional approaches are reaching a saturation point, in terms of coding efficiency, a new generation of video coding techniques, aiming at a deeper “understanding” of the image, is being studied. In this context, image analysis, particularly the identification of objects or regions in images (segmentation), is a very important step. This paper describes a segmentation algorithm based on split and merge. Images are first simplified using mathematical morphology operators, which eliminate perceptually less relevant details. The simplified image is then split according to a quad tree structure and the resulting regions are finally merged in three steps: merge, elimination of small regions and control of the number of regions.
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Papers by Manuel Menezes de Sequeira
O artigo descreve um projecto-piloto na área da gestão de configurações e de activos de serviço desenvolvido, no âmbito de um trabalho académico, em colaboração estreita com a Direcção de Serviços de Informática do ISCTE-IUL. Embora o artigo se foque fundamentalmente nos aspectos de implementação do processo referido, de acordo com as melhores práticas do ITIL, descreve também a componente de business intelligence do projecto-piloto. Esta componente consiste num sistema de reporte (reporting), assente na plataforma de business intelligence da Microsoft, destinado a colmatar a deficiente capacidade de reporte da ferramenta de gestão de activos actualmente em utilização na universidade.
The software used for evaluation and a set of annotated evaluation images are both readily available, making the reproduction of the presented results possible. The availability of both software and an evaluation set allows the results presented in this paper to be used as benchmarks when developing plate location algorithms.
This is due to the fact that a new fourth criterion, based on new user needs, has been overlooked: content access effort. The new user needs have also been recognized by MPEG-4, which intends to develop an audio-visual coding standard addressing new content based functionalities. MPEG-4 will also guarantee its own future evolution and extensibility through the use of a flexible syntax and the provision for programmable codecs.
This paper proposes an architecture for a four-criteria mid-level vision video codec that will be the basis for a future MPEG-4 proposal. The blocks of the codec and the interfaces between them are described. The main blocks of the codec, namely image and motion analysis, are discussed in detail and some possible solutions are proposed.
This paper extends previous work on still image segmentation using split & merge to deal also with moving images. The technique proposed performs a time-recursive segmentation. Time recursion is introduced by using a region-growing like version of the original segmentation algorithm such that the previously segmented regions are projected into the current image. The results obtained show that the technique is a good candidate for image analysis in the framework of second-generation moving image coding.
This paper also overviews the partition coding techniques which address the considered partition types and which use the identified partition representations. Emphasis is given to binary partition coding techniques proposed within the framework of MPEG-4.
The new image coding approaches require the identification of regions or "objects", i.e., image segmentation. This process results in an image partition matrix, which includes contour information, and a set of parameters characterising each region according to a given set of image features.
The contour information represents an extremely important and sensitive information for the human visual system, being thus also of great importance in the image coding context.
This paper proposes a classification of partition and contour models according to a tree structure, in order to clearly identify the contour models to which contour coding techniques can be applied. It also proposes a lossless contour coding technique based on Freeman's chain codes.
Since conventional video coding techniques are reaching a saturation point, a new generation of techniques, aiming at a deeper “understanding” of the image, is being studied. In this context, image analysis, particularly the identification of regions or objects in images (segmentation), is an important step in very low bitrate video coding, since it will lead to a better representation of images and consequently to an improvement of the encoded image quality (for a fixed bitrate).
This paper describes a segmentation algorithm based on split & merge and shortest spanning trees (SST). The image is first split according to a quad tree structure and then the resulting regions are merged, using the SST concept, in three steps: merge, elimination of small regions and control of the number of regions.
Results are presented for video sequences from studio and mobile videotelephony, which show the good properties of the algorithm for application in very low bitrate video coding schemes.
This thesis presents new architectures for second-generation video codecs and some of the required analysis and coding tools.
The graph theoretic foundations of image analysis are presented and algorithms for generalized shortest spanning tree problems are proposed. In this light, it is shown that basic versions of several region-oriented segmentation algorithms address the same problem. Globalization of information is studied and shown to confer different properties to these algorithms, and to transform region merging in recursive shortest spanning tree segmentation (RSST). RSST algorithms attempting to minimize global approximation error and using affine region models are shown to be very effective. A knowledge-based segmentation algorithm for mobile videotelephony is proposed.
A new camera movement estimation algorithm is developed which is effective for image stabilization and scene cut detection. A camera movement compensation technique for first-generation codecs is also proposed.
A systematization of partition types and representations is performed with which partition coding tools are overviewed. A fast approximate closed cubic spline algorithm is developed with applications in partition coding.
O artigo descreve um projecto-piloto na área da gestão de configurações e de activos de serviço desenvolvido, no âmbito de um trabalho académico, em colaboração estreita com a Direcção de Serviços de Informática do ISCTE-IUL. Embora o artigo se foque fundamentalmente nos aspectos de implementação do processo referido, de acordo com as melhores práticas do ITIL, descreve também a componente de business intelligence do projecto-piloto. Esta componente consiste num sistema de reporte (reporting), assente na plataforma de business intelligence da Microsoft, destinado a colmatar a deficiente capacidade de reporte da ferramenta de gestão de activos actualmente em utilização na universidade.
The software used for evaluation and a set of annotated evaluation images are both readily available, making the reproduction of the presented results possible. The availability of both software and an evaluation set allows the results presented in this paper to be used as benchmarks when developing plate location algorithms.
This is due to the fact that a new fourth criterion, based on new user needs, has been overlooked: content access effort. The new user needs have also been recognized by MPEG-4, which intends to develop an audio-visual coding standard addressing new content based functionalities. MPEG-4 will also guarantee its own future evolution and extensibility through the use of a flexible syntax and the provision for programmable codecs.
This paper proposes an architecture for a four-criteria mid-level vision video codec that will be the basis for a future MPEG-4 proposal. The blocks of the codec and the interfaces between them are described. The main blocks of the codec, namely image and motion analysis, are discussed in detail and some possible solutions are proposed.
This paper extends previous work on still image segmentation using split & merge to deal also with moving images. The technique proposed performs a time-recursive segmentation. Time recursion is introduced by using a region-growing like version of the original segmentation algorithm such that the previously segmented regions are projected into the current image. The results obtained show that the technique is a good candidate for image analysis in the framework of second-generation moving image coding.
This paper also overviews the partition coding techniques which address the considered partition types and which use the identified partition representations. Emphasis is given to binary partition coding techniques proposed within the framework of MPEG-4.
The new image coding approaches require the identification of regions or "objects", i.e., image segmentation. This process results in an image partition matrix, which includes contour information, and a set of parameters characterising each region according to a given set of image features.
The contour information represents an extremely important and sensitive information for the human visual system, being thus also of great importance in the image coding context.
This paper proposes a classification of partition and contour models according to a tree structure, in order to clearly identify the contour models to which contour coding techniques can be applied. It also proposes a lossless contour coding technique based on Freeman's chain codes.
Since conventional video coding techniques are reaching a saturation point, a new generation of techniques, aiming at a deeper “understanding” of the image, is being studied. In this context, image analysis, particularly the identification of regions or objects in images (segmentation), is an important step in very low bitrate video coding, since it will lead to a better representation of images and consequently to an improvement of the encoded image quality (for a fixed bitrate).
This paper describes a segmentation algorithm based on split & merge and shortest spanning trees (SST). The image is first split according to a quad tree structure and then the resulting regions are merged, using the SST concept, in three steps: merge, elimination of small regions and control of the number of regions.
Results are presented for video sequences from studio and mobile videotelephony, which show the good properties of the algorithm for application in very low bitrate video coding schemes.
This thesis presents new architectures for second-generation video codecs and some of the required analysis and coding tools.
The graph theoretic foundations of image analysis are presented and algorithms for generalized shortest spanning tree problems are proposed. In this light, it is shown that basic versions of several region-oriented segmentation algorithms address the same problem. Globalization of information is studied and shown to confer different properties to these algorithms, and to transform region merging in recursive shortest spanning tree segmentation (RSST). RSST algorithms attempting to minimize global approximation error and using affine region models are shown to be very effective. A knowledge-based segmentation algorithm for mobile videotelephony is proposed.
A new camera movement estimation algorithm is developed which is effective for image stabilization and scene cut detection. A camera movement compensation technique for first-generation codecs is also proposed.
A systematization of partition types and representations is performed with which partition coding tools are overviewed. A fast approximate closed cubic spline algorithm is developed with applications in partition coding.