Efficient Run-length Encoding Of Binary Sources With Unknown Statistics

An efficient run-length encoding of binary sources with unknown statistics was discussed. Binary entropy coders, which were used in multimedia codec standards and used adaptive Golomb-Rice coders, were also discussed. The uses of two subsets of Golomb parameters were also proposed. Polynomials whose roots were used to determine the optimal values of the Golomb parameters were derived. A nearly-optimal adaption strategy was derived, using a maximum-liklihood approach.534Tanaka, H., Leon-Garcia, A., Efficient run-length encoding (1982) IEEE Trans. Information Theory, IT-28, pp. 880-890. , NovCosta, M.H.M., Malvar, H.S., Efficient run-length encoding of binary sources with unknown statistics (2003) Microsoft Research Tech. Report, TR-2003-95. , De

Contributions in image and video coding

Orientador: Max Henrique Machado CostaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: A comunidade de codificação de imagens e vídeo vem também trabalhando em inovações que vão além das tradicionais técnicas de codificação de imagens e vídeo. Este trabalho é um conjunto de contribuições a vários tópicos que têm recebido crescente interesse de pesquisadores na comunidade, nominalmente, codificação escalável, codificação de baixa complexidade para dispositivos móveis, codificação de vídeo de múltiplas vistas e codificação adaptativa em tempo real. A primeira contribuição estuda o desempenho de três transformadas 3-D rápidas por blocos em um codificador de vídeo de baixa complexidade. O codificador recebeu o nome de Fast Embedded Video Codec (FEVC). Novos métodos de implementação e ordens de varredura são propostos para as transformadas. Os coeficiente 3-D são codificados por planos de bits pelos codificadores de entropia, produzindo um fluxo de bits (bitstream) de saída totalmente embutida. Todas as implementações são feitas usando arquitetura com aritmética inteira de 16 bits. Somente adições e deslocamentos de bits são necessários, o que reduz a complexidade computacional. Mesmo com essas restrições, um bom desempenho em termos de taxa de bits versus distorção pôde ser obtido e os tempos de codificação são significativamente menores (em torno de 160 vezes) quando comparados ao padrão H.264/AVC. A segunda contribuição é a otimização de uma recente abordagem proposta para codificação de vídeo de múltiplas vistas em aplicações de video-conferência e outras aplicações do tipo "unicast" similares. O cenário alvo nessa abordagem é fornecer vídeo com percepção real em 3-D e ponto de vista livre a boas taxas de compressão. Para atingir tal objetivo, pesos são atribuídos a cada vista e mapeados em parâmetros de quantização. Neste trabalho, o mapeamento ad-hoc anteriormente proposto entre pesos e parâmetros de quantização é mostrado ser quase-ótimo para uma fonte Gaussiana e um mapeamento ótimo é derivado para fonte típicas de vídeo. A terceira contribuição explora várias estratégias para varredura adaptativa dos coeficientes da transformada no padrão JPEG XR. A ordem de varredura original, global e adaptativa do JPEG XR é comparada com os métodos de varredura localizados e híbridos propostos neste trabalho. Essas novas ordens não requerem mudanças nem nos outros estágios de codificação e decodificação, nem na definição da bitstream A quarta e última contribuição propõe uma transformada por blocos dependente do sinal. As transformadas hierárquicas usualmente exploram a informação residual entre os níveis no estágio da codificação de entropia, mas não no estágio da transformada. A transformada proposta neste trabalho é uma técnica de compactação de energia que também explora as similaridades estruturais entre os níveis de resolução. A idéia central da técnica é incluir na transformada hierárquica um número de funções de base adaptativas derivadas da resolução menor do sinal. Um codificador de imagens completo foi desenvolvido para medir o desempenho da nova transformada e os resultados obtidos são discutidos neste trabalhoAbstract: The image and video coding community has often been working on new advances that go beyond traditional image and video architectures. This work is a set of contributions to various topics that have received increasing attention from researchers in the community, namely, scalable coding, low-complexity coding for portable devices, multiview video coding and run-time adaptive coding. The first contribution studies the performance of three fast block-based 3-D transforms in a low complexity video codec. The codec has received the name Fast Embedded Video Codec (FEVC). New implementation methods and scanning orders are proposed for the transforms. The 3-D coefficients are encoded bit-plane by bit-plane by entropy coders, producing a fully embedded output bitstream. All implementation is performed using 16-bit integer arithmetic. Only additions and bit shifts are necessary, thus lowering computational complexity. Even with these constraints, reasonable rate versus distortion performance can be achieved and the encoding time is significantly smaller (around 160 times) when compared to the H.264/AVC standard. The second contribution is the optimization of a recent approach proposed for multiview video coding in videoconferencing applications or other similar unicast-like applications. The target scenario in this approach is providing realistic 3-D video with free viewpoint video at good compression rates. To achieve such an objective, weights are computed for each view and mapped into quantization parameters. In this work, the previously proposed ad-hoc mapping between weights and quantization parameters is shown to be quasi-optimum for a Gaussian source and an optimum mapping is derived for a typical video source. The third contribution exploits several strategies for adaptive scanning of transform coefficients in the JPEG XR standard. The original global adaptive scanning order applied in JPEG XR is compared with the localized and hybrid scanning methods proposed in this work. These new orders do not require changes in either the other coding and decoding stages or in the bitstream definition. The fourth and last contribution proposes an hierarchical signal dependent block-based transform. Hierarchical transforms usually exploit the residual cross-level information at the entropy coding step, but not at the transform step. The transform proposed in this work is an energy compaction technique that can also exploit these cross-resolution-level structural similarities. The core idea of the technique is to include in the hierarchical transform a number of adaptive basis functions derived from the lower resolution of the signal. A full image codec is developed in order to measure the performance of the new transform and the obtained results are discussed in this workDoutoradoTelecomunicações e TelemáticaDoutor em Engenharia Elétric

Techniques of design optimisation for algorithms implemented in software

The overarching objective of this thesis was to develop tools for parallelising, optimising, and implementing algorithms on parallel architectures, in particular General Purpose Graphics Processors (GPGPUs). Two projects were chosen from different application areas in which GPGPUs are used: a defence application involving image compression, and a modelling application in bioinformatics (computational immunology). Each project had its own specific objectives, as well as supporting the overall research goal. The defence / image compression project was carried out in collaboration with the Jet Propulsion Laboratories. The specific questions were: to what extent an algorithm designed for bit-serial for the lossless compression of hyperspectral images on-board unmanned vehicles (UAVs) in hardware could be parallelised, whether GPGPUs could be used to implement that algorithm, and whether a software implementation with or without GPGPU acceleration could match the throughput of a dedicated hardware (FPGA) implementation. The dependencies within the algorithm were analysed, and the algorithm parallelised. The algorithm was implemented in software for GPGPU, and optimised. During the optimisation process, profiling revealed less than optimal device utilisation, but no further optimisations resulted in an improvement in speed. The design had hit a local-maximum of performance. Analysis of the arithmetic intensity and data-flow exposed flaws in the standard optimisation metric of kernel occupancy used for GPU optimisation. Redesigning the implementation with revised criteria (fused kernels, lower occupancy, and greater data locality) led to a new implementation with 10x higher throughput. GPGPUs were shown to be viable for on-board implementation of the CCSDS lossless hyperspectral image compression algorithm, exceeding the performance of the hardware reference implementation, and providing sufficient throughput for the next generation of image sensor as well. The second project was carried out in collaboration with biologists at the University of Arizona and involved modelling a complex biological system – VDJ recombination involved in the formation of T-cell receptors (TCRs). Generation of immune receptors (T cell receptor and antibodies) by VDJ recombination is an enormously complex process, which can theoretically synthesize greater than 1018 variants. Originally thought to be a random process, the underlying mechanisms clearly have a non-random nature that preferentially creates a small subset of immune receptors in many individuals. Understanding this bias is a longstanding problem in the field of immunology. Modelling the process of VDJ recombination to determine the number of ways each immune receptor can be synthesized, previously thought to be untenable, is a key first step in determining how this special population is made. The computational tools developed in this thesis have allowed immunologists for the first time to comprehensively test and invalidate a longstanding theory (convergent recombination) for how this special population is created, while generating the data needed to develop novel hypothesis

Three-dimensional Transforms And Entropy Coders For A Fast Embedded Color Video Codec

This work compares the performances of two fast 3-D transforms and two adaptive Golomb entropy coders applied to a video codec system named FEVC (Fast Embedded Video Codec). The compared transforms are Hadamard (4×4×4 and 8×8×8) and H.264/AVC integer DCT (4×4×4). The compared adaptive Golomb entropy coders have different operation modes and adaptation strategies. New 3-D implementation methods for the transforms are presented. After the scan procedure, the encoding of the 3-D coefficients is done, bit-plane-by-bit-plane, by the entropy coders, producing a fully embedded output bitstream. The FEVC (also described here) was developed to be implemented each of a large number of set-top boxes used in a fiber optics network. For that reason, it is focused on reduced complexity and execution time, not on high compression rates. The use of meager computational resources is also required. Even with these constraints, good distortion versus rate results were achieved. © 2008 IEEE.147154Jain, A.K., (1989) Fundamentals of Digital Image Processing, , Prentice Hall, Englewood Cliffs, NJ, USAMalvar, H., Hallapuro, A., Karczewicz, M., Kerofsky, L., Low-Complexity Transform and Quantization with 16-bit Arithmetic for H.26L (2002) Proceedings of the International Conference on Image Processing - ICIP, pp. 489-492Oliveira, F.C., Costa, M.H.M., Embedded DCT Image Encoding (2002) International Telecommunications Symposium - ITS-2002, , Natal, Brazil, SeptCosta, M.H.M., Malvar, H.S., Efficient Run-Length Encoding of Binary Sources with Unknown Statistics (2004) Proceedings of the Data Compression Conference, pp. 534-544. , Snowbird, UT, USA, ppChan, R.K.W., Lee, M.C., 3D-DCT Quantization as a Compression Technique for Video Sequences (1997) Proceedings of the International Conference On Virtual Systems And Multimedia, pp. 188-196. , Geneva, Switzerland, ppChan, R.K.W., Lee, M.C., Quantization of 3D-DCT Coefficients and Scan Order for Video Compression (1997) Journal of Visual Communication and Image Representation, 8 (4), pp. 405-422Testoni, V., Costa, M.H.M., 3D-Hadamard Coefficients Sequency Scan Order for a Fast Embedded Color Video Coded (2007) Proceedings of the International Conference on Signal Processing and Communication Systems, pp. 75-82. , Gold Coast, Australia, ppSullivan, G., Estrop, S., (2003) Video Rendering with 8-bit YUVFormats, , Microsoft Digital Media DivisionSullivan, G., Topiwala, P., Luthra, A., The H.264/ AVC Advanced Video Coding Standard: Overview and Introduction to the Fidelity Range Extensions (2004) Conference on Applications of Digital Image ProcessingShen, K., DeIp, E.J., Wavelet Based Rate Scalable Video Compression (1999) IEEE Transactions on Circuits and Systems for Video Technology, 9 (1), pp. 109-122Kim, B., Xiong, Z., Pearlman, W.A., Low Bit Rate Scalable Video Coding with 3D Set Partitioning in Hierarchical Trees (3D SPIHT) (2000) IEEE Transactions on Circuits and Systems for Video Technology, 10 (8), pp. 1374-1387H.264/AVC reference software version JM 11.0, , http://iphome.hhi.de/suehring/tml, Downloaded in Dec. 200