The JPEG2000 still image compression standard

The development of standards (emerging and established) by the International Organization for Standardization (ISO), the International Telecommunications Union (ITU), and the International Electrotechnical Commission (IEC) for audio, image, and video, for both transmission and storage, has led to worldwide activity in developing hardware and software systems and products applicable to a number of diverse disciplines [7], [22], [23], [55], [56], [73]. Although the standards implicitly address the basic encoding operations, there is freedom and flexibility in the actual design and development of devices. This is because only the syntax and semantics of the bit stream for decoding are specified by standards, their main objective being the compatibility and interoperability among the systems (hardware/software) manufactured by different companies. There is, thus, much room for innovation and ingenuity. Since the mid 1980s, members from both the ITU and the ISO have been working together to establish a joint international standard for the compression of grayscale and color still images. This effort has been known as JPEG, the Join

Layer-based coding, smoothing, and scheduling of low-bit-rate video for teleconferencing over tactical ATM networks

This work investigates issues related to distribution of low bit rate video within the context of a teleconferencing application deployed over a tactical ATM network. The main objective is to develop mechanisms that support transmission of low bit rate video streams as a series of scalable layers that progressively improve quality. The hierarchical nature of the layered video stream is actively exploited along the transmission path from the sender to the recipients to facilitate transmission. A new layered coder design tailored to video teleconferencing in the tactical environment is proposed. Macroblocks selected due to scene motion are layered via subband decomposition using the fast Haar transform. A generalized layering scheme groups the subbands to form an arbitrary number of layers. As a layering scheme suitable for low motion video is unsuitable for static slides, the coder adapts the layering scheme to the video content. A suboptimal rate control mechanism that reduces the kappa dimensional rate distortion problem resulting from the use of multiple quantizers tailored to each layer to a 1 dimensional problem by creating a single rate distortion curve for the coder in terms of a suboptimal set of kappa dimensional quantizer vectors is investigated. Rate control is thus simplified into a table lookup of a codebook containing the suboptimal quantizer vectors. The rate controller is ideal for real time video and limits fluctuations in the bit stream with no corresponding visible fluctuations in perceptual quality. A traffic smoother prior to network entry is developed to increase queuing and scheduler efficiency. Three levels of smoothing are studied: frame, layer, and cell interarrival. Frame level smoothing occurs via rate control at the application. Interleaving and cell interarrival smoothing are accomplished using a leaky bucket mechanism inserted prior to the adaptation layer or within the adaptation layerhttp://www.archive.org/details/layerbasedcoding00parkLieutenant Commander, United States NavyApproved for public release; distribution is unlimited

Design and performance evaluation of smart dissemination of emergence messages in vehicular ad-hoc networks

The growing demand to improve road safety and optimize road traffic has generated great interest in vehicular ad-hoc network (VANETs). Serious traffic accidents can cause financial losses, physical disability, and even death. However, if drivers were informed about the danger in advance through a warning message, this would give drivers enough time to react appropriately to the situation. There are many approaches that can prevent car accidents, and VANETs have been conceived as an excellent solution to improve road safety, through the use of a variety of applications enabled by vehicle communications. The key objective of this research is to achieve information dissemination from a vehicle to other vehicles around that migth be interested in receiving the content. We focus on the network layer and application layer protocols, which are discussed and developed as a protocol over the respective access technologies. We primarily present the research results of our proposals, and also provide a comprehensive review of existing challenges and solutions in data dissemination in VANETs. Our proposals include the design of three dissemination protocols compatible with the IEEE 802.11p standards for road safety applications. These dissemination protocols can be differentiated by their application trigger condition and the broadcast scheme. All three dissemination protocols have been implemented in the simulator VEINS to perform several large-scale experiments. The results of the experiments have shown that all three dissemination protocols are able to cope with an increasing number of vehicles in large scale scenarios without sufering a noticeable loss in performance. Finally, we have investigated solutions to increase the driver's privacy because VANETs can also introduce some location privacy risk by periodically broadcast beacon messages that include the vehicle's position. We evaluate the performance of the privacy schemes, described the experiments and discussed the results.La creixent demanda per millorar la seguretat viària i optimitzar el trànsit viari ha generat gran interès en les xarxes vehiculars ad-hoc (VANETs). Els accidents de trànsit greus poden causar pèrdues financeres, discapacitat física i fins i tot la mort. No obstant això, si els conductors van ser informats per endavant sobre el perill a través d’un missatge d’advertència, això donaria als conductors el temps suficient per reaccionar de manera apropiada a la situació. Hi ha molts enfocaments que poden prevenir accidents automobilístics, i les VANETs s’han concebut com una excel·lent solució per millorar la seguretat viària, a través de l’ús d’una varietat d’aplicacions habilitades per les comunicacions vehiculars. L’objectiu principal d’aquesta investigació és aconseguir la disseminació de la informació des d’un vehicle a altres vehicles que estiguin interessats en rebre el contingut. Ens enfoquem en la capa de xarxa i els protocols de capa d’aplicació, que es discuteixen i desenvolupen com un protocol sobre les respectives tecnologies d'accés. Principalment vam presentar els resultats d’investigació de les nostres propostes, i també provem una revisió exhaustiva dels desafiaments i solucions existents en la disseminació de dades en les VANETs. Les nostres propostes inclouen el disseny de tres protocols de disseminació compatibles amb els estàndards IEEE 802.11p per a aplicacions de seguretat viària. Aquests protocols de disseminació es poden diferenciar per la condició d’activació de l’aplicació i l’esquema de difusió. Els tres protocols de disseminació s’han implementat en el simulador VEINS per a realitzar diversos experiments a gran escala. Els resultats dels experiments han demostrat que els tres protocols de disseminació són capaços de fer front a un nombre creixent de vehicles en escenaris de gran escala sense patir una pèrdua notable en el rendiment. Finalment, hem investigat solucions per augmentar la privacitat del conductor perquè les VANETs també poden introduir algun risc de privacitat de la ubicació mitjanant missatges beacon emesos periòdicament que inclouen la posició dels vehicles. Avaluem l’acompliment dels esquemes de privacitat, descrivim els experiments i discutim els resultats.Postprint (published version

The JPEG2000 still image coding system: An overview

With the increasing use of multimedia technologies, image compression requires higher performance as well as new features. To address this need in the specific area of still image encoding, a new standard is currently being developed, the JPEG2000. It is not only intended to provide rate-distortion and subjective image quality performance superior to existing standards, but also to provide features and functionalities that current standards can either not address efficiently or in many cases cannot address at all. Lossless and lossy compression, embedded lossy to lossless coding, progressive transmission by pixel accuracy and by resolution, robustness to the presence of bit-errors and region-of-interest coding, are some representative features. It is interesting to note that JPEG2000 is being designed to address the requirements of a diversity of applications, e.g. Internet, color facsimile, printing, scanning, digital photography, remote sensing, mobile applications, medical imagery, digital library and E-commerce

Fuzzy Logic Control of Adaptive ARQ for Video Distribution over a Bluetooth Wireless Link

Bluetooth's default automatic repeat request (ARQ) scheme is not suited to video distribution resulting in missed display and decoded deadlines. Adaptive ARQ with active discard of expired packets from the send buffer is an alternative approach. However, even with the addition of cross-layer adaptation to picture-type packet importance, ARQ is not ideal in conditions of a deteriorating RF channel. The paper presents fuzzy logic control of ARQ, based on send buffer fullness and the head-of-line packet's deadline. The advantage of the fuzzy logic approach, which also scales its output according to picture type importance, is that the impact of delay can be directly introduced to the model, causing retransmissions to be reduced compared to all other schemes. The scheme considers both the delay constraints of the video stream and at the same time avoids send buffer overflow. Tests explore a variety of Bluetooth send buffer sizes and channel conditions. For adverse channel conditions and buffer size, the tests show an improvement of at least 4 dB in video quality compared to nonfuzzy schemes. The scheme can be applied to any codec with I-, P-, and (possibly) B-slices by inspection of packet headers without the need for encoder intervention.</jats:p