Mobile devices are increasingly being used to access Web content but lack the resources for proper presentation to the user. To address this problem, content is typically customized to be more suitable for a mobile environment. Automatic customization of web content is a challenging problem because fine-grain adaptation often depends on both the relevance of individual objects on a web page, as well as the context of access (e.g., screen size of device being used, network connectivity, location, etc.). We present Usage-aware Interactive Content Adaptation, an adaptation technique that allows a user who is unsatisfied with the system’s adaptation decision to take control of the adaptation process and make changes until the content is suitably adapted for her purposes. The adaptation system learns from the user’s modifications and adjusts its prediction for future accesses by other users. With this approach, users are empowered to correct bad adaptation decisions made by the system without being overly burdened. We applied the technique in two domains: adapting the quality of images to reduce download times and save energy and bandwidth, and customizing the layout of images to improve the utilization of screen real-estate. The work was evaluated through a series of user studies, and the results show that user feedback can be effectively used to provide appropriate customizations (i) for objects with varying relevance, (ii) when context affects the users adaptation requirements, and (iii) when the same content can be used for multiple purposes by different users.

Mobile devices are increasingly being used to access Web content but lack the resources for proper presentation to the user. To address this problem, content is typically customized to be more suitable for a mobile environment. Automatic customization of web content is a challenging problem because fine-grain adaptation often depends on both the relevance of individual objects on a web page, as well as the context of access (e.g., screen size of device being used, network connectivity, location, etc.). We present Usage-aware Interactive Content Adaptation, an adaptation technique that allows a user who is unsatisfied with the system’s adaptation decision to take control of the adaptation process and make changes until the content is suitably adapted for her purposes. The adaptation system learns from the user’s modifications and adjusts its prediction for future accesses by other users. With this approach, users are empowered to correct bad adaptation decisions made by the system without being overly burdened. We applied the technique in two domains: adapting the quality of images to reduce download times and save energy and bandwidth, and customizing the layout of images to improve the utilization of screen real-estate. The work was evaluated through a series of user studies, and the results show that user feedback can be effectively used to provide appropriate customizations (i) for objects with varying relevance, (ii) when context affects the users adaptation requirements, and (iii) when the same content can be used for multiple purposes by different users.

Mobile phones, tablet computers, laptops, desktops, and large screen displays are increasingly available to individuals for information access, often simultaneously. Dominant content access protocols, such as HTTP/1.1, do not take advantage of this device multiplicity and support information access from single devices only. Changing devices means restarting an information session. Using devices in conjunction with each other poses several challenges, which include the presentation of content on devices with diverse form factors and propagation of the content changes across these devices. In this dissertation, I report on the design and implementation of MIDAS - architecture and a prototype system for multi-device presentations. I propose a framework, called 12C, for characterizing multi-device systems and evaluate MIDAS within this framework. MIDAS is designed as a middleware that can work with multiple client-server architectures, such as the Web and context-aware Trellis, a non-Web hypertext system. It presents information content simultaneously on devices with diverse characteristics without requiring sensor-enhanced environments. The system adapts content elements for optimal presentation on the target device while also striving to retain fidelity with the original form from a human perceptual perspective. MIDAS reconfigures its presentation in response to user actions, availability of devices, and environmental context, such as a user's location or the time of day. I conducted a pilot study that explored human perception of similarity when image attributes such as size and color depth are modified in the process of presenting images on different devices. The results indicated that users tend to prefer scaling of images to color-depth reduction but gray scaling of images is preferable to either modification. Not all images scale equally gracefully; those dominated by natural elements or manmade structures scale exceptionally well. Images that depict recognizable human faces or textual elements should be scaled only to an extent that these features retain their integrity. Attributes of the 12C framework describe aspects of multi-device systems that include infrastructure, presentation, interaction, interface, and security. Based on these criteria, MIDAS is a flexible infrastructure, which lends itself to several content distribution and interaction strategies by separating client- and server-side configuration.

The phenomenal growth in the use of the World Wide Web often places a heavy load on networks and servers, threatening to increase Web server response time and raising scalability issues for both the network and the server. With the advances in the field of optical networking and the increasing use of broadband technologies like cable modems and DSL, the server and not the network, is more likely to be the bottleneck. Many clients are willing to receive a degraded, less resource intensive version of the requested content as an alternative to connection failures. In this thesis, we present an adaptive content delivery system that transparently switches content depending on the load on the server in order to serve more clients. Our system is designed to work for dynamic Web pages and streaming multimedia traffic, which are not currently supported by other adaptive content approaches. We have designed a system which is capable of quantifying the load on the server and then performing the necessary adaptation. We designed a streaming MPEG server and client which can react to the server load by scaling the quality of frames transmitted. The main benefits of our approach include: transparent content switching for content adaptation, alleviating server load by a graceful degradation of server performance and no requirement of modification to existing server software, browsers or the HTTP protocol. We experimentally evaluate our adaptive server system and compare it with an unadaptive server. We find that adaptive content delivery can support as much as 25% more static requests, 15% more dynamic requests and twice as many multimedia requests as a non-adaptive server. Our, client-side experiments performed on the Internet show that the response time savings from our system are quite significant.

This thesis provides a novel architecture for the creation and management of virtual multimedia adaptation services offered by a multimedia-enabled cloud. The aim of the proposed scheme is to provide an optimal yet a transparent user access to adapted media contents while isolating them from the heterogeneity of the utilized devices, diversity of media formats, as well as the details of the adaptation services and performance variations of the underlying network. This goal is achieved through the development of service virtualization models that provide various levels of abstraction of the actual physical services and their performance parameters. Such virtual models offer adaptation functions by comprising adaptation services with accordance to their parameters. Additionally, parameters describing the functional specifics of the adaptation functions, as well as multimedia content features, are organized into a hierarchical structure that facilitates extraction of the virtual models capable of satisfying the conditions expressed by the user requests. At the same time the paramter/feature organization structure itself is flexible enough to allow users to specify media delivery requests at various levels of request details (e.g., summarize video vs. drop specific frames). As a result, in response to a user request for a multimedia content, an optimal virtual service adaptation path is calculated, describing the needed media adaptation operations as well as the appropriate mapping to the physical resources capable of executing such functions. The selection of the adaptation path is done with the use of a novel performance-history based selection mechanism that takes into account the performance variations and relations of the services in a dynamically changing environment of multimedia clouds. A number of experiments are conducted to demonstrate the potential of the proposed work in terms of the enhanced processing time and service quality.

This thesis provides a novel architecture for the creation and management of virtual multimedia adaptation services offered by a multimedia-enabled cloud. The aim of the proposed scheme is to provide an optimal yet a transparent user access to adapted media contents while isolating them from the heterogeneity of the utilized devices, diversity of media formats, as well as the details of the adaptation services and performance variations of the underlying network. This goal is achieved through the development of service virtualization models that provide various levels of abstraction of the actual physical services and their performance parameters. Such virtual models offer adaptation functions by comprising adaptation services with accordance to their parameters. Additionally, parameters describing the functional specifics of the adaptation functions, as well as multimedia content features, are organized into a hierarchical structure that facilitates extraction of the virtual models capable of satisfying the conditions expressed by the user requests. At the same time the paramter/feature organization structure itself is flexible enough to allow users to specify media delivery requests at various levels of request details (e.g., summarize video vs. drop specific frames). As a result, in response to a user request for a multimedia content, an optimal virtual service adaptation path is calculated, describing the needed media adaptation operations as well as the appropriate mapping to the physical resources capable of executing such functions. The selection of the adaptation path is done with the use of a novel performance-history based selection mechanism that takes into account the performance variations and relations of the services in a dynamically changing environment of multimedia clouds. A number of experiments are conducted to demonstrate the potential of the proposed work in terms of the enhanced processing time and service quality.

[pt] Serviços para disseminação de informações (serviços push) têm sido amplamente utilizados, em particular para aplicações envolvendo usuários móveis. Estes serviços geralmente atendem a dispositivos com recursos bem diferenciados e em contextos de execução (conectividade sem fio, reserva de energia, etc.) distintos, fazendo necessário adaptar o conteúdo difundido dinamica- e individualmente para cada cliente. Uma vez que muitas adaptações de conteúdo envolvem operações custosas e demandam alto poder de processamento, estas não devem ser realizadas nos clientes móveis. Por outro lado, executar no servidor, as adaptações para cada cliente móvel, torna- se pouco eficiente e escalável. Assim, em tais serviços, é comum utilizar-se intermediários dedicados às adaptações de conteúdo (de acordo com o contexto) dos clientes. Comunicação assíncrona, como publish/subscribe, é considerada por muitos como a mais apropriada para este tipo de serviço. Por outro lado, sistemas para adaptação de conteúdo sensível a contexto não dão suporte a este tipo de comunicação, até porque a adaptação precisa ser individual, e portanto conflita com o paradigma de comunicação um-para-muitos. Neste trabalho apresentamos uma arquitetura para sistemas publish/subscribe com adaptação sensível a contexto, que utiliza um algoritmo que otimiza a adaptação de conteúdo para grandes conjuntos de clientes de uma difusão. / [en] Services for information dissemination (push services) are being widely used, in particular for applications involving mobile users. These services generally serve devices with diferent resources and with distinct execution contexts (wireless connectivity, energy source, etc.), making it necessary to adapt disseminated content individual and dynamically for each client. Since many content adaptations involve costly operations and demand high processing power, these should not be executed at the mobile clients. On the other hand, it is neither efficient nor scalable to execute the adaptations for each mobile client at the server. Thus, in such services, it is common to use proxies dedicated to content adaptations (based on the context) of clients. Asynchronous communication, such as publish/- subscribe, is considered the most appropriate form of communication for this type of service. On the other hand, systems for context-aware content adaptation do not support this type of communication. In this thesis we present an architecture for publish/subscribe systems with context-aware content adaptation, that uses an algorithm that optimizes the content adaptation for large sets of clients.

This thesis provides a novel architecture for the creation and management of virtual multimedia adaptation services offered by a multimedia-enabled cloud. The aim of the proposed scheme is to provide an optimal yet a transparent user access to adapted media contents while isolating them from the heterogeneity of the utilized devices, diversity of media formats, as well as the details of the adaptation services and performance variations of the underlying network. This goal is achieved through the development of service virtualization models that provide various levels of abstraction of the actual physical services and their performance parameters. Such virtual models offer adaptation functions by comprising adaptation services with accordance to their parameters. Additionally, parameters describing the functional specifics of the adaptation functions, as well as multimedia content features, are organized into a hierarchical structure that facilitates extraction of the virtual models capable of satisfying the conditions expressed by the user requests. At the same time the paramter/feature organization structure itself is flexible enough to allow users to specify media delivery requests at various levels of request details (e.g., summarize video vs. drop specific frames). As a result, in response to a user request for a multimedia content, an optimal virtual service adaptation path is calculated, describing the needed media adaptation operations as well as the appropriate mapping to the physical resources capable of executing such functions. The selection of the adaptation path is done with the use of a novel performance-history based selection mechanism that takes into account the performance variations and relations of the services in a dynamically changing environment of multimedia clouds. A number of experiments are conducted to demonstrate the potential of the proposed work in terms of the enhanced processing time and service quality.

O trabalho apresentado nesta tese trata do desenvolvimento de técnicas com suporte à ciência de contexto, baseadas nos padrões MPEG-4 e MPEG-7, para personalizar e adaptar conteúdo em TV Interativa. Um dos desafios dessa área é desenvolvimento de programas personalizados com rico conteúdo multimídia, com alta interatividade e que, além disso, sejam acessíveis a partir de uma variedade de dispositivos (fixos ou móveis), atendendo às expectativas de interação e de acesso dos usuários. Grande parte do problema está no fato de que os modos encontrados na literatura para representar, descrever e compor programas de TV Interativa não oferecem suporte a contexto, não permitem a separação entre descrições de programas e descrições de objetos e possuem baixa granulosidade de segmentação. Essas características dificultam e, em alguns casos, impedem o desenvolvimento de aplicações avançadas em TV Interativa. As técnicas desenvolvidas neste trabalho são baseadas em esquemas de descrição, compatíveis com o padrão MPEG-7, e na segmentação de programas em objetos MPEG-4. Os esquemas são utilizados para descrever a estrutura, a composição e a semântica de programas e de seus objetos componentes. Também foi definida e implantada uma infra-estrutura para produção, distribuição e consumo de programas. A utilização conjunta da infra-estrutura e das técnicas permite o desenvolvimento de aplicações avançadas em TV Interativa. Como um exemplo dessas aplicações, foi desenvolvido um serviço automático para personalizar e adaptar programas de TV Interativa, permitindo que um usuário possa acessar, sob demanda, programas especialmente produzidos para ele, contendo apenas assuntos de seu interesse e permitindo que o acesso possa ser realizado por dispositivos fixos ou móveis. / The work presented in this thesis developed techniques with context-awareness support, based on the MPEG-4 and MPEG-7 standards, in order to personalize and to adapt Interactive TV content. One of the challenges in this area is the development of personalized programs with rich multimedia content, high interactivity and accessibility through a variety of devices (mobile and non-mobile). Most part of the problem is that the approaches found in literature do not provide context support, do not allow separation between programs and objects descriptions and have low level of segmentation granularity. These features make difficult or impossible, in some cases, the development of Interactive TV applications. The techniques developed in this work are based on MPEG-7 compliant schemes and on programs segmentation into MPEG-4 objects. The schemes are used to describe structure, composition and semantics of programs and component objects. An infra-structure to creation, delivery and consumption of Interactive TV programs was also defined. The joint utilization of infra-structure and techniques allows for the development of Interactive TV advanced applications. As an example of these applications, this work developed an automatic Interactive TV personalization and adaptation service. This service allows a user to access, on-demand, a program specially designed to match his interests and allowing content access through devices with mobile and non-mobile features.

O trabalho apresentado nesta tese trata do desenvolvimento de técnicas com suporte à ciência de contexto, baseadas nos padrões MPEG-4 e MPEG-7, para personalizar e adaptar conteúdo em TV Interativa. Um dos desafios dessa área é desenvolvimento de programas personalizados com rico conteúdo multimídia, com alta interatividade e que, além disso, sejam acessíveis a partir de uma variedade de dispositivos (fixos ou móveis), atendendo às expectativas de interação e de acesso dos usuários. Grande parte do problema está no fato de que os modos encontrados na literatura para representar, descrever e compor programas de TV Interativa não oferecem suporte a contexto, não permitem a separação entre descrições de programas e descrições de objetos e possuem baixa granulosidade de segmentação. Essas características dificultam e, em alguns casos, impedem o desenvolvimento de aplicações avançadas em TV Interativa. As técnicas desenvolvidas neste trabalho são baseadas em esquemas de descrição, compatíveis com o padrão MPEG-7, e na segmentação de programas em objetos MPEG-4. Os esquemas são utilizados para descrever a estrutura, a composição e a semântica de programas e de seus objetos componentes. Também foi definida e implantada uma infra-estrutura para produção, distribuição e consumo de programas. A utilização conjunta da infra-estrutura e das técnicas permite o desenvolvimento de aplicações avançadas em TV Interativa. Como um exemplo dessas aplicações, foi desenvolvido um serviço automático para personalizar e adaptar programas de TV Interativa, permitindo que um usuário possa acessar, sob demanda, programas especialmente produzidos para ele, contendo apenas assuntos de seu interesse e permitindo que o acesso possa ser realizado por dispositivos fixos ou móveis. / The work presented in this thesis developed techniques with context-awareness support, based on the MPEG-4 and MPEG-7 standards, in order to personalize and to adapt Interactive TV content. One of the challenges in this area is the development of personalized programs with rich multimedia content, high interactivity and accessibility through a variety of devices (mobile and non-mobile). Most part of the problem is that the approaches found in literature do not provide context support, do not allow separation between programs and objects descriptions and have low level of segmentation granularity. These features make difficult or impossible, in some cases, the development of Interactive TV applications. The techniques developed in this work are based on MPEG-7 compliant schemes and on programs segmentation into MPEG-4 objects. The schemes are used to describe structure, composition and semantics of programs and component objects. An infra-structure to creation, delivery and consumption of Interactive TV programs was also defined. The joint utilization of infra-structure and techniques allows for the development of Interactive TV advanced applications. As an example of these applications, this work developed an automatic Interactive TV personalization and adaptation service. This service allows a user to access, on-demand, a program specially designed to match his interests and allowing content access through devices with mobile and non-mobile features.