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Projeto de arquiteturas integradas para a compressão de imagens JPEG; Design of architectures for jpeg image compression

Agostini, Luciano Volcan
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
POR
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Esta dissertação apresenta o desenvolvimento de arquiteturas para a compressão JPEG, onde são apresentadas arquiteturas de um compressor JPEG para imagens em tons de cinza, de um compressor JPEG para imagens coloridas e de um conversor de espaço de cores de RGB para YCbCr. As arquiteturas desenvolvidas são detalhadamente apresentadas, tendo sido completamente descritas em VHDL, com sua síntese direcionada para FPGAs da família Flex10KE da Altera. A arquitetura integrada do compressor JPEG para imagens em tons de cinza possui uma latência mínima de 237 ciclos de clock e processa uma imagem de 640x480 pixels em 18,5ms, permitindo uma taxa de processamento de 54 imagens por segundo. As estimativas realizadas em torno da taxa de compressão obtida indicam que ela seria de aproximadamente 6,2 vezes ou de 84 %. A arquitetura integrada do compressor JPEG para imagens coloridas foi gerada a partir de adaptações na arquitetura do compressor para imagens em tons de cinza. Esta arquitetura também possui a latência mínima de 237 ciclos de clock, sendo capaz de processar uma imagem coloria de 640 x 480 pixels em 54,4ms, permitindo uma taxa de processamento de 18,4 imagens por segundo. A taxa de compressão obtida, segundo estimativas...

Compressão de dados de demanda elétrica em Smart Metering; Data compression electricity demand in Smart Metering

Andrea Carolina Flores Rodriguez
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 08/08/2014 PT
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A compressão dos dados de consumo residencial de energia elétrica registrados torna-se extremadamente necessária em Smart Metering, a fim de resolver o problema de grandes volumes de dados gerados pelos medidores. A principal contribuição desta tese é a proposta de um esquema de representação teórica da informação registrada na forma mais compacta, sugerindo uma forma de atingir o limite fundamental de compressão estabelecido pela entropia da fonte sobre qualquer técnica de compressão disponibilizada no medidor. A proposta consiste na transformação de codificação dos dados, baseado no processamento por segmentação: no tempo em taxas de registros de 1/900 Hz a 1 Hz, e nos valores de consumo residencial de energia elétrica. Este último subdividido em uma compressão por amplitude mudando sua granularidade e compressão dos dados digitais para representar o consumo com o menor número de bits possíveis usando: PCM-Huffman, DPCM-Huffman e codificação de entropia supondo diferentes ordens de distribuição da fonte. O esquema é aplicado sobre dados modelados por cadeias de Markov não homogêneas para as atividades dos membros da casa que influenciam no consumo elétrico e dados reais disponibilizados publicamente. A avaliação do esquema é feita analisando o compromisso da compressão entre as altas taxas de registro...

Lossless compression algorithms for microarray images and whole genome alignments; Algoritmos de compressão sem perdas para imagens de microarrays e alinhamento de genomas completos

Matos, Luís Miguel de Oliveira
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
ENG
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Nowadays, in the 21st century, the never-ending expansion of information is a major global concern. The pace at which storage and communication resources are evolving is not fast enough to compensate this tendency. In order to overcome this issue, sophisticated and efficient compression tools are required. The goal of compression is to represent information with as few bits as possible. There are two kinds of compression, lossy and lossless. In lossless compression, information loss is not tolerated so the decoded information is exactly the same as the encoded one. On the other hand, in lossy compression some loss is acceptable. In this work we focused on lossless methods. The goal of this thesis was to create lossless compression tools that can be used in two types of data. The first type is known in the literature as microarray images. These images have 16 bits per pixel and a high spatial resolution. The other data type is commonly called Whole Genome Alignments (WGA), in particularly applied to MAF files. Regarding the microarray images, we improved existing microarray-specific methods by using some pre-processing techniques (segmentation and bitplane reduction). Moreover, we also developed a compression method based on pixel values estimates and a mixture of finite-context models. Furthermore...

Effect of quality, porosity and density on the compression properties of cork

Anjos, Ofélia; Pereira, Helena; Rosa, Emilia
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em //2008 ENG
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The compression properties of cork were studied on samples obtained from cork planks of two commercial quality classes (good and poor quality), with densities ranging from 0.12–0.20g cm−3 and porosities from0.5 to 22.0%. The stress-strain curves were characterized by an elastic region up to approximately 5% strain, followed by a large plateau up to 60% strain caused by the progressive buckling of cell walls, and a steep stress increase for higher strains corresponding to cell collapse. The direction of compression was a highly significant factor of variation, with cork showing higher strength for the radial compression. Density influenced compression and cork samples with higher density showed overall larger resistance to compression in the three directions. In the elastic region, an exponential model of Young’s modulus in function of cork density could be adjusted. The effect of porosity on compression was small and the stress-strain curves were similar regardless of the porosity of the samples, although there was a trend toward an overall increase of stress with porosity for higher strains. Porosity was characterised by a high variability in the anatomical features of the lenticular filling material and the presence of collapsed and thick walled lignified cells. The inclusion of a porosity parameter for the modelling of the elastic modulus did not improve the prediction obtained with densitybased models. There was no significant difference in the compression properties of cork samples obtained from cork planks of good and poor quality classes.

Compression specific toughness of normal strength steel fiber reinforced concrete (NSSFRC) and high strength steel fiber reinforced concrete (HSSFRC)

Marara,Khaled; Erenb,Özgür; Yitmena,İbrahim
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 EN
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Compression toughness tests were carried out on concrete cylinders reinforced with three different aspect ratios of hooked-end steel fibers 60, 75, and 83 and six different percentages of steel fibers 0.5, 1.0, 1.25, 1.5, 1.75, and 2.0% by volume of concrete. The w/c ratio used for the normal strength steel fiber reinforced concrete mixes (NSSFRC) was 0.55, and the water-cementitious ratio (w/c+s) for the high strength fiber reinforced concrete mixes (HSSFRC) was 0.31. For each mix, three test cylinders were tested for compression specific toughness. The effect of fiber reinforcement index: volume of fibers × length/diameter ratio on compression specific toughness and also on the relationship between these two properties is presented in this paper. As a result, (a) equations are proposed to quantify the effect of fibers on compression toughness ratio of concrete in terms of FRI, (b) equations obtained in terms of FRI and compression specific toughness of plain concrete to estimate both compression specific toughness of NSSFRC and HSSFRC (N.m), (c) equations obtained which represent the relationship between compression toughness index and FRI for NSSFRC and HSSFRC, respectively, and (d) equations obtained to quantify the relationship between compression specific toughness index and fiber reinforcement index for NSSFRC and HSSFRC...

Einfluss der Kompressionstherapie bei Radsportlern mit nachgewiesener Klappeninsuffizienz der Hautstammvenen auf Leistungsvermögen und Laktatspiegel; The effect of compression stockings on lactate level and performance in cyclists with venous insufficiency

Rauschenbach, Matthias
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
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Einführung: Venöse Rezirkulation mit nachfolgendem kapillären Hochdruck könnte den oxidativen Muskelstoffwechsel beeinflussen. Ziel der vorliegenden Studie war es, den Einfluss der chronischen venösen Insuffizienz (CVI) und ihrer therapeutischen Korrektur durch Kompressionsstrümpfe auf das Leistungsvermögen, den Laktatspiegel und die subjektiven Beschwerden von Langstreckenradsportlern zu untersuchen. Methoden: Es wurde eine offene prospektive randomisierte, 40 Tage andauernde Kohortenstudie an 18 Radsportlern (16 männlich, 2 weiblich) durchgeführt. Anhand der CEAP-Klassifikation wurde die CVI der Radsportler in die klinischen Stadien C2-3, EP; AS,P, PR eingeteilt. Zur Kompressionstherapie wurden individuell angepasste Kompressionsstrümpfe (Venotrain Champion A-D, Kompressionsklasse 2, Bauerfeind Deutschland) verwendet. Standardisierte mehrstufige Belastungstests auf dem Fahrradergometer wurden durchgeführt und der kapilläre Blutlaktatspiegel bestimmt sowie Daten zu subjektiven Beschwerden und zur Lebensqualität erhoben. Ergebnisse: Es gab keinen akuten Effekt der medizinischen Kompressionstherapie auf Leistungsvermögen, Herzfrequenz und Laktatspiegel im Vergleich der Ergebnisse der Leistungstests mit und ohne Kompressionsstrümpfe. Ebenso konnte kein signifikanter Unterschied zwischen einem Leistungstest ohne und mit Kompression nach einer Kompressionstherapiedauer von 4 Wochen gefunden werden. Die Kompressionstherapie führte zu einer signifikanten Reduktion von CVI-typischen Beschwerden im Alltag und nach dem Training. Die Kompressionsstrümpfe wurden von den Sportlern sowohl im Alltag als auch unter Trainingsbedingungen gut akzeptiert. Schlussfolgerung: Eine Verbesserung der Leistungsfähigkeit von Radsportlern mit venöser Insuffizienz konnte durch die Akut- und Langzeittherapie mit Kompressionsstrümpfen nicht gezeigt werden. Andererseits wurde die Leistungsfähigkeit der Sportler durch die Kompressionstherapie auch nicht beeinträchtigt. Durch das Tragen der Kompressionsstrümpfe entstand subjektiv ein großer Nutzen. Kompressionsstrümpfe sollten Radsportlern mit venöser Insuffizienz empfohlen werden.; Introduction: Venous recirculation with subsequent capillary hypertension might influence oxidative muscle metabolism. The aim of the present study was to examine the influence of chronic venous insufficiency (CVI) and its therapeutic correction by compression stockings on performance...

Einfluss der Kompressionstherapie bei Läufern mit nachgewiesener Klappeninsuffizienz der Hautstammvenen auf Leistungsvermögen und Laktatspiegel; The effect of compression stockings on lactate level and performance in runners with venous insufficiency

Kemmler, Johannes
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
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Einführung: Venöse Rezirkulation mit nachfolgendem kapillären Hochdruck bei chronisch venöser Insuffizienz (CVI) könnte den oxidativen Muskelstoffwechsel beeinflussen. In dieser Studie wurde der Einfluss der chronisch venösen Insuffizienz und deren therapeutische Korrektur durch medizinische Kompressionsstrümpfe auf Leistungsvermögen, Laktatspiegel und subjektive Beschwerden von Läufern untersucht. Methoden: Es wurde eine offene, prospektive, randomisierte Kohortenstudie über 40 Tage an 24 Probanden (13 Männer, 11 Frauen) durchgeführt. Die venöse Situation wurde mittels der klinischen Untersuchung sowie apparativer Diagnostik (Farbkodierte Duplexsonographie, Digitale Photoplethysmographie) beurteilt und anhand der CEAP-Klassifikation eingeteilt. Zur Kompressionstherapie wurden individuell angepasste Kompressionsstrümpfe (Venotrain Champion A-D, Kompressionsklasse 2, Bauerfeind Deutschland) verwendet. Standardisierte mehrstufige Belastungstests auf dem Laufbandergometer mit Bestimmung von kapillären Blutlaktatwerten wurden durchgeführt sowie Daten zu subjektiven Beschwerden und Lebensqualität mithilfe eines Fragebogens erhoben. Ergebnisse: Die durchschnittliche wöchentliche Lauftrainingsstrecke der Probanden betrug 53...

Compression of Static and Dynamic Three-Dimensional Meshes; Kompression statischer und dynamischer dreidimensionaler Netze

Amjoun, Rachida
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
EN
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With the advancements and variety of sources to model 3D objects such as scanning technologies and modelling softwares, 3D models are becoming widely available. Animation also attracted worldwide attention and has become one of the most successful application of digital media technology. As a result, it is also becoming easier to acquire animated models. In order to achieve a higher degree of realism, more complex and highly detailed three-dimensional objects – possibly out of millions of vertices and polygons – are created with large sequences. When storing, downloading, or uploading these 3D sequences of objects in their standard forms over a network, large data rows consume large amounts of storage space and network bandwidth. This problem of storage and transmission has been widely studied for static meshes and wealth of successful compression schemes have been proposed. The main goal of this thesis is to develop new powerful compression techniques to reduce storage requirements and transmission times of static and dynamic 3D models represented by triangulated mesh and introduce new and efficient animation segmentation approaches that are very useful for different purposes, typically 3D dynamic mesh compression. This work covers five main parts. The first part presents definitions...

Baseband Signal Compression in Wireless Base Stations

Vosoughi, Aida; Wu, Michael; Cavallaro, Joseph R.
Fonte: IEEE Publicador: IEEE
Tipo: Conference paper
ENG
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To comply with the evolving wireless standards, base stations must provide greater data rates over the serial data link between base station processor and RF unit. This link is especially important in distributed antenna systems and cooperating base stations settings. This paper explores the compression of baseband signal samples prior to transfer over the above-mentioned link. We study lossy and lossless compression of baseband signals and analyze the cost and gain of each approach. Sample quantizing is proposed as a lossy compression scheme and it is shown to be effective by experiments. With QPSK modulation, sample quantizing achieves a compression ratio of 4:1 and 3.5:1 in downlink and uplink, respectively. The corresponding compression ratios are 2.3:1 and 2:1 for 16-QAM. In addition, lossless compression algorithms including arithmetic coding, Elias-gamma coding, and unused significant bit removal, and also a recently proposed baseband signal compression scheme are evaluated. The best compression ratio achieved for lossless compression is 1.5:1 in downlink. Our over-the-air experiments suggest that compression of baseband signal samples is a feasible and promising solution for increasing the effective bit rates of the link to/from remote RF units without requiring much complexity and cost to the base station.

Radiographers practice concerning breast compression in mammography: gradual versus no gradual

Bule, Marta; Reis, Cláudia
Fonte: Springer Publicador: Springer
Tipo: Conferência ou Objeto de Conferência
Publicado em /03/2014 ENG
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Purpose: Evaluate the type of breast compression (gradual or no gradual) that provides less discomfort to the patient. Methods and Materials: The standard projections were simulated [craniocaudal/(CC) and mediolateral-oblique/(MLO)] with the two breast compressions in 90 volunteers women aged between 19 and 86. The women were organised in groups according to the breast density. The intensity of discomfort was evaluated using the scale that have represented several faces (0-10) proposed by Wong Baker in the end of each simulation. It was also applied an interview using focus group to debate the score that were attributed during pain evaluation and to identify the criteria that were considered to do the classification. Results: The women aged between 19-29y (with higher breast density) classified the pain during no gradual compression as 4 and the gradual compression as 2 for both projections. The MLO projection was considered the most uncomfortable. During the focus group interview applied to this group was highlighted that compression did not promoted pain but discomfort. They considered that the high expectations of pain did not correspond to the discomfort that they felt. Similar results were identified for the older women (30-50y; > 50y). Conclusion: The radiographers should considerer the technique for breast compression. The gradual compression was considered for the majority of the women as the most comfortable regardless of breast density. The MLO projection was considered as uncomfortable due to the positioning (axila and inclusion of pectoral muscle) and due to the higher breast compression compared to the CC projection.

Einfluss unterschiedlicher Kompressionsstrümpfe auf die Hauttemperatur und die Hautfeuchtigkeit während laufbandergometrischer Belastung; The influence of different compression stockings on the temperature and the moisture of the skin during the strain on a treadmill

Sohns, Andrea
Fonte: Universität Tübingen Publicador: Universität Tübingen
Tipo: Dissertation; info:eu-repo/semantics/doctoralThesis
DE_DE
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Fragestellung: In der vorliegenden Studie wurde der Einfluss zweier unterschiedlicher konfektionierter Kompressionsstrümpfe auf die folgenden Eigenschaften der Haut am Unterschenkel vor, während und nach einer standardisierten Belastung untersucht: Hauttemperatur, transepidermaler Wasserverlust und Hautfeuchtigkeit. Die Kompressionsprodukte wurden außerdem bezüglich der Aufnahme von Wasser, ihres Anpressdrucks, ihrer Wirksamkeit und des Tragekomforts miteinander verglichen. Material und Methoden: An der Studie nahmen 20 weibliche Patienten mit chronisch venöser Insuffizienz im Stadium I und II nach Widmer teil. Die Patienten wurden an 2 unterschiedlichen Untersuchungstagen laufbandergometrisch bei 12° Steigung und 3 km/h 15 Minuten belastet, wobei ein Bein einen Kompressionsstrumpf trug und das andere unbekleidet blieb. Vor und nach der Belastung wurden der transepidermale Wasserverlust sowie die Hautfeuchtigkeit beider Beine in Höhe des medialen Malleolus und der Wade ermittelt. Während des Laufens wurde die Hauttemperatur der beiden Beine in Höhe des medialen Knöchels und der Verlauf des Anpressdruckes der Kompressionsstrümpfe an 4 Lokalisationen pro Unterschenkel aufgezeichnet. Außerdem wurde die Aufnahme von Wasser in den Kompressionsstrumpf und an einem weiteren Untersuchungstermin mit Hilfe der Quecksilberstreifenplethysmographie die hämodynamische Wirkung der Kompressionsstrümpfe bestimmt. Nach 2-3tägigem Tragen der Kompressionsprodukte wurde ein Fragebogen zum Tragekomfort ausgefüllt. Ergebnisse: Hauttemperatur...

Perceptual Criteria on Image Compression

Moreno Escobar, Jesús Jaime
Fonte: [Barcelona] : Universitat Autònoma de Barcelona, Publicador: [Barcelona] : Universitat Autònoma de Barcelona,
Tipo: Tesis i dissertacions electròniques; info:eu-repo/semantics/doctoralThesis; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2011 ENG
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Hoy en día las imágenes digitales son usadas en muchas areas de nuestra vida cotidiana, pero estas tienden a ser cada vez más grandes. Este incremento de información nos lleva al problema del almacenamiento de las mismas. Por ejemplo, es común que la representación de un pixel a color ocupe 24 bits, donde los canales rojo, verde y azul se almacenen en 8 bits. Por lo que, este tipo de pixeles en color pueden representar uno de los 224 ¼ 16:78 millones de colores. Así, una imagen de 512 £ 512 que representa con 24 bits un pixel ocupa 786,432 bytes. Es por ello que la compresión es importante. Una característica importante de la compresión de imágenes es que esta puede ser con per didas o sin ellas. Una imagen es aceptable siempre y cuando dichas perdidas en la información de la imagen no sean percibidas por el ojo. Esto es posible al asumir que una porción de esta información es redundante. La compresión de imágenes sin pérdidas es definida como deco dificar matemáticamente la misma imagen que fue codificada. En la compresión de imágenes con pérdidas se necesita identificar dos características: la redundancia y la irrelevancia de in formación. Así la compresión con pérdidas modifica los datos de la imagen de tal manera que cuando estos son codificados y decodificados...

Diagnostically lossless compression strategies for x-ray angiography images

Xu, Zhongwei
Fonte: [Barcelona] : Universitat Autònoma de Barcelona, Publicador: [Barcelona] : Universitat Autònoma de Barcelona,
Tipo: Tesis i dissertacions electròniques; info:eu-repo/semantics/doctoralThesis; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2015 SPA
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En las últimas décadas se han producido mejoras significativas en las técnicas de imagen médica. Hoy en día, el uso de estas técnicas es habitual en la mayoría de sistemas sanitarios, y las imágenes producidas forman parte integral de las fichas de los pacientes. De entre las modalidades de imagen médica habitualmente empleadas, los rayos X es una de las más populares gracias a su bajo coste, alta resolución y su excelente capacidad para penetrar dentro de los tejidos. Dentro de la familia de la imagen de rayos X, las angiografías de rayos X --las cuales emplean cateterización minimamente invaisva-- se emplean rutinariamente para detectar irregularidades en el sistema vascular. Las imágenes de angiografías de rayos X se pueden clasificar en dos typos: angiografía de rayos X general (GXA) ,las cuales presentan los vasos sanguíneos de diferentes partes del cuerpo como brazos, piernas, pies, etc., y las secuencias de video de angiogramas coronarios (CAVSs), las cuales muestran solo los árboles de los vasos coronarios para el diagnóstico de enfermedades cardiovasculares. Dadas las diferencias en cuanto a función, estos dos tipos de imagen presentan características muy diferentes. Las imágenes GXA suelen poseer una alta resolución espacial...

DNA Microarray Image Compression

Hernández-Cabronero, Miguel
Fonte: [Barcelona] : Universitat Autònoma de Barcelona, Publicador: [Barcelona] : Universitat Autònoma de Barcelona,
Tipo: Tesis i dissertacions electròniques; info:eu-repo/semantics/doctoralThesis; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2015 ENG
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En los experimentos con DNA microarrays se genran dos imágenes monocromo, las cuales es conveniente almacenar para poder realizar análisis más precisos en un futuro. Por tanto, la compresión de imágenes surge como una herramienta particularmente útil para minimizar los costes asociados al almacenamiento y la transmisión de dichas imágenes. Esta tesis tiene por objetivo mejorar el estado del arte en la compresión de imágenes de DNA microarrays. Como parte de esta tesis, se ha realizado una detallada investigación de las características de las imágenes de DNA microarray. Los resultados experimentales indican que los algoritmos de compresión no adaptados a este tipo de imágenes producen resultados más bien pobres debido a las características de estas imágenes. Analizando las entropías de primer orden y condicionales, se ha podido determinar un límite aproximado a la compresibilidad sin pérdida de estas imágenes. Aunque la compresión basada en contexto y en segmentación proporcionan mejoras modestas frente a algoritmos de compresión genéricos, parece necesario realizar avances rompedores en el campo de compresión de datos para superar los ratios 2:1 en la mayor parte de las imágenes. Antes del comienzo de esta tesis se habían propuesto varios algoritmos de compresión sin pérdida con rendimientos cercanos al límite óptimo anteriormente mencionado. Sin embargo...

zlib compression library

Gailly, Jean-loup; Adler, Mark
Fonte: Universidade de Cambridge Publicador: Universidade de Cambridge
Tipo: Relatório Formato: 1505280 bytes; application/x-tar
EN_GB
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(taken from http://www.gzip.org/ on 2004-12-01) zlib is designed to be a free, general-purpose, legally unencumbered -- that is, not covered by any patents -- lossless data-compression library for use on virtually any computer hardware and operating system. The zlib data format is itself portable across platforms. Unlike the LZW compression method used in Unix compress(1) and in the GIF image format, the compression method currently used in zlib essentially never expands the data. (LZW can double or triple the file size in extreme cases.) zlib's memory footprint is also independent of the input data and can be reduced, if necessary, at some cost in compression. A more precise, technical discussion of both points is available on another page. zlib was written by Jean-loup Gailly (compression) and Mark Adler (decompression). Jean-loup is also the primary author/maintainer of gzip(1), the author of the comp.compression FAQ list and the former maintainer of Info-ZIP's Zip; Mark is also the author of gzip's and UnZip's main decompression routines and was the original author of Zip. Not surprisingly, the compression algorithm used in zlib is essentially the same as that in gzip and Zip, namely, the `deflate' method that originated in PKWARE's PKZIP 2.x. Greg...

An Experimental analysis of the MPEG compression standard with respect to processing requirements, compression ratio, and image quality

Howard, Daniel
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
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As computer use and capabilities have grown, people have become more interested in being able to create and access varies types of multimedia content. The MPEG video compression technique provides a method for compressing video content down to a size that computers and networks can handle. To properly make use of this algorithm it is necessary to understand the trade-offs that exist when choosing among the various options of the MPEG algorithm. Background information on the MPEG-1, MPEG-2 and MPEG-4 algorithms is presented. This thesis then provides an understanding of the trade-offs of applying different compression and decompression options of the MPEG-1 algorithm on various types of video streams. This allows recommendations on which options should be used for specific categories of video sequences to be made. The performance of an existing implementation of the MPEG compression and decompression algorithm is analysed to determine these resulting trade-offs . Various types of video sequences are used to observe the results of changing the various parameters of the algorithm. Some of the parameters that are investigated include the percentage of the I (only spatially compressed), P (forward predicted), and B (bi-directionally predicted) frames in the compressed stream and the individual quantization of each of these frames. The results from each of the video sequences when these parameters are modified and analysed with respect to overall CR (compression ratio)...

An Investigation into the effect of the compression algorithm in the presence of shifting and cropping on image quality

Thonggoom, Ornsiri
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
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Image compression is a form of data compression frequently used in digital imaging applications to improve the efficiency of transmission and storage. In order to have a manageable file size, the data compression is lossy, i.e. image information is lost. Lossy compression algorithms such as Baseline JPEG use the insensitivity of the human eye to high frequency information as a basis for the compression. Discrete cosine transforms (DCT) are performed on the data followed by variable quantization. And the image blocking has no exact regulations for the spatial variation. Using this technique, information is lost and the decompressed image is a distorted version of the original. It is known that simple repeated compressions do not influence image quality, which is deter mined by the initial compression. Considering practical use, this study extends JPEG operation to the repeated DCT block rearrangement operation of the JPEG baseline scheme. In particular image placement and translation are discussed. Objectively and subjectively analytical results are presented. It is now shown that these operations affect total image quality. The error of the JPEG image quality tends to increase with the number of repetitive DCT rearrangement operations...

A Comparative study of the compression strength of corrugated shipping containers and corrugated board, based on different corrugation directions

Curatalo, Richard
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
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This study evaluates compression damage to corrugated shipping containers used in the small parcel delivery system. A client is experiencing an unacceptable level of end-to-end compression resistance during shipment through small parcel companies, while never experiencing any top-to-bottom compression damage. According to small parcel company workers, there is a need for more end-to-end compression strength in corrugated shipping containers. This study examines the effect of corrugation direction on corrugated shipping containers and corrugated board. Box compression testing (BCT) is performed on regular-slotted containers with different corrugation directions. Edgewise compression testing (ECT) is also used in comparing the compression strengths of sample corrugated boards with various corrugation directions. ECT and BCT values directly relate to the compression resistant properties of corrugated containers and board. The results of the tests show that compression strength increases less as corrugation becomes more perpendicular to the applied force. By altering the corrugation direction, the end-to-end compression strength can be increased at a higher percentage rate than the top-to-bottom compression strength is reduced.

Analysis of digital audio compression and digital rights management techniques

Majewicz, Eric
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Outros Formato: 560321 bytes; application/pdf
EN_US
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This paper starts with an initial discussion on digital audio principles, which is important to understanding advanced digital audio concepts such as compression. The process by which an analog waveform is converted into its digital equivalent is done in three steps: sampling, quantization, and coding. Sampling and quantization take the analog signal, which is a continuous voltage varying with time, and divides it into discrete intervals. Coding is the process by which this information is represented as a series of digital words. A discussion is also presented on the major uncompressed digital audio format for PC, the WAVE file format. The main focus of this paper is on lossless and lossy compression techniques and their applications. Lossless compression techniques such as Huffman Coding, Arithmetic Coding, and Dictionary-based Coding remove redundancies in the content and code the information as efficiently as possible. These techniques are rarely used alone because of the small compression ratios that they provide as compared to lossy techniques. Lossy compression takes advantage of the fact that the human ear does not perceive all frequencies equally. Instead, critical bands in the ear divide up the frequency spectrum and perceive these bands with different fidelity. Lossy compression techniques that use these principles are discussed...

Lossless Compression Method for Medical Image Sequences Using Super-Spatial Structure Prediction and Inter-frame Coding

Raza,Mudassar; Adnan,Ahmed; Sharif,Muhammad; Haider,Syed Waqas
Fonte: UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico Publicador: UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2012 EN
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Space research organizations, hospitals and military air surveillance activities, among others, produce a huge amount of data in the form of images hence a large storage space is required to record this information. In hospitals, data produced during medical examination is in the form of a sequence of images and are very much correlated; because these images have great importance, some kind of lossless image compression technique is needed. Moreover, these images are often required to be transmitted over the network. Since the availability of storage and bandwidth is limited, a compression technique is required to reduce the number of bits to store these images and take less time to transmit them over the network. For this purpose, there are many state-of the-art lossless image compression algorithms like CALIC, LOCO-I, JPEG-LS, JPEG20000; Nevertheless, these compression algorithms take only a single file to compress and cannot exploit the correlation among the sequence frames of MRI or CE images. To exploit the correlation, a new algorithm is proposed in this paper. The primary goals of the proposed compression method are to minimize the memory resource during storage of compressed data as well as minimize the bandwidth requirement during transmission of compressed data. For achieving these goals...