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114 results on '"Blanes, Ian"'

1. Lower Bounds on the Redundancy of Huffman Codes with Known and Unknown Probabilities

Author

Blanes, Ian, Hernández-Cabronero, Miguel, Serra-Sagristà, Joan, and Marcellin, Michael W.

Subjects
Computer Science - Information Theory
Abstract

In this paper we provide a method to obtain tight lower bounds on the minimum redundancy achievable by a Huffman code when the probability distribution underlying an alphabet is only partially known. In particular, we address the case where the occurrence probabilities are unknown for some of the symbols in an alphabet. Bounds can be obtained for alphabets of a given size, for alphabets of up to a given size, and for alphabets of arbitrary size. The method operates on a Computer Algebra System, yielding closed-form numbers for all results. Finally, we show the potential of the proposed method to shed some light on the structure of the minimum redundancy achievable by the Huffman code.

Published
2018
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2. Room Escape at Class: Escape Games Activities to Facilitate the Motivation and Learning in Computer Science

Author

Borrego, Carlos, Fernández, Cristina, Blanes, Ian, and Robles, Sergi

Abstract

Real-life room-escape games are ludic activities in which participants enter a room in order to get out of it only after solving some riddles. In this paper, we explain a Room Escape teaching experience developed in the Engineering School at Universitat Autònoma de Barcelona. The goal of this activity is to increase student's motivation and to improve their learning on two courses of the second year in the "Computer Engineering degree: Computer Networks and Information and Security". [Paper presented at the International Conference on University Teaching and Innovation (CIDUI): Learning and Teaching Innovation Impacts (9th, Bellaterra, Barcelona, Spain, Jul 5-7 2016.)]

Published
2017

9. The New CCSDS Standard for Low-Complexity Lossless and Near-Lossless Multispectral and Hyperspectral Image Compression

Author

Kiely, Aaron B, Klimesh, Matthew, Blanes, Ian, Ligo, Jonathan, Magli, Enrico, Aranki, Nazeeh, Burl, Michael, Camarero, Roberto, Cheng, Michael, Dolinar, Sam, Dolman, David, Flesch, Greg, Ghassemi, Hamid, Gilbert, Martin, Hernández-Cabronero, Miguel, Keymeulen, Didier, Le, Martin, Luong, Huy, McGuinness, Christopher, Moury, Gilles, Pham, Thang, Plintovic, Martin, Sala, Frederic, Santos, Lucana, Schaar, Alan, Serra-Sagrist, Joan, Shin, Simon, Sundlie, Brenton, Valsesia, Diego, Vitulli, Raffaele, Wong, Englin, Wu, William, Xie, Hua, and Zhou, Hanying

Subjects
Computer Programming And Software
Abstract

This paper describes the emerging Issue 2 of the CCSDS-123.0-B standard for low-complexity compression of multispectral and hyperspectral imagery, focusing on its new features and capabilities. Most significantly, this new issue incorporates a closed-loop quantization scheme to provide near-lossless compression capability while still supporting lossless compression, and introduces a new entropy coding option that provides better compression of low-entropy data.

Published
2018

11. Coding Performance Impact on a Constant-Weight Predictor for CCSDS 123.0-B-2

Author

Bartrina-Rapesta, Joan, Hernández-Cabronero, Miguel, Sanchez, Antonio, Barrios, Yubal, Sarmiento, Roberto, Serra-Sagristà, Joan, and Blanes, Ian

Subjects
CCSDS 123.0-B-2, fast compression, data compression, low computational predictor
Abstract

In 2019, the 123.0-B-2 standard titled “Low-Complexity Lossless and Near-Lossless Multispectral and Hyperspectral Image Compression” was presented. It introduced a near-lossless operation mode and a new state-of-the-art entropy encoder to provide efficient coding of the low-entropy data often produced by the new in-loop quantizer included in the standard. This article shows that tunning properly some parameters during the coding process, the weight update stage of a CCSDS 123.0-B-2 predictor can be bypassed, yielding a faster encoder at expenses of likely compression ratios. Experimental results show the coding performance penalization bypassing the weight updating, compared with a regular coding process --when the weights are updated-, for lossless and near-lossless compression. Coding performance analysis is provided for Hyperion, Aviris, Modis and Airs instruments. Results suggest that, bypass the weight updating produces a lossless coding performance penalization about 4\%. For near-lossless, a higher coding penalty is produced as the step size, in the inner loop quantizer of the predictor, is larger.

Published
2022
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21. Review and Implementation of the Emerging CCSDS Recommended Standard for Multispectral and Hyperspectral Lossless Image Coding

Author

Sanchez, Jose Enrique, Auge, Estanislau, Santalo, Josep, Blanes, Ian, Serra-Sagrista, Joan, and Kiely, Aaron

Subjects
Instrumentation And Photography
Abstract

A new standard for image coding is being developed by the MHDC working group of the CCSDS, targeting onboard compression of multi- and hyper-spectral imagery captured by aircraft and satellites. The proposed standard is based on the "Fast Lossless" adaptive linear predictive compressor, and is adapted to better overcome issues of onboard scenarios. In this paper, we present a review of the state of the art in this field, and provide an experimental comparison of the coding performance of the emerging standard in relation to other state-of-the-art coding techniques. Our own independent implementation of the MHDC Recommended Standard, as well as of some of the other techniques, has been used to provide extensive results over the vast corpus of test images from the CCSDS-MHDC.

Published
2011

22. A NOVEL ARCHITECTURE FOR A HIGH-SPEED-INTEGRATED SATELLITE DATA CHAIN INCLUDING AN ONBOARD ROUTING NETWORK, DATA PROCESSING & STORAGE AND DIRECT-TO-EARTH DOWNLINK CAPABILITIES USING OPTICAL COMMUNICATION AND A KA-BAND RF LINK

Author

Wertz, Philipp, Hespeler, Bernd, Parkes, Steve, Ramirez, Julio, Roth, Manuel, Matuz, Balazs, Bischl, Hermann, Steiner, Martin, Staehle, Michael, Wagner, Arnaud, Blanes, Ian, Serra-Sagristà, Serra-Sagristà, Kranitis, Nektarios, Tsigkanos, Antonis, and Paschalis, Antonis

Subjects
Packet Level Coding, Optical Downlink, DIRECT-TO-EARTH DOWNLINK
Published
2019

23. High-performance lossless compression of hyperspectral remote sensing scenes based on spectral decorrelation

Author

Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), European Space Agency, Generalitat de Catalunya, Ministerio de Economía y Competitividad (España), European Commission, Hernández-Cabronero, Miguel, Portell, Jordi, Blanes, Ian, Serra-Sagristà, Joan, Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), European Space Agency, Generalitat de Catalunya, Ministerio de Economía y Competitividad (España), European Commission, Hernández-Cabronero, Miguel, Portell, Jordi, Blanes, Ian, and Serra-Sagristà, Joan

Abstract

The capacity of the downlink channel is a major bottleneck for applications based on remote sensing hyperspectral imagery (HSI). Data compression is an essential tool to maximize the amount of HSI scenes that can be retrieved on the ground. At the same time, energy and hardware constraints of spaceborne devices impose limitations on the complexity of practical compression algorithms. To avoid any distortion in the analysis of the HSI data, only lossless compression is considered in this study. This work aims at finding the most advantageous compression–complexity trade-off within the state of the art in HSI compression. To do so, a novel comparison of the most competitive spectral decorrelation approaches combined with the best performing low-complexity compressors of the state is presented. Compression performance and execution time results are obtained for a set of 47 HSI scenes produced by 14 different sensors in real remote sensing missions. Assuming only a limited amount of energy is available, obtained data suggest that the FAPEC algorithm yields the best trade-off. When compared to the CCSDS 123.0-B-2 standard, FAPEC is 5.0 times faster and its compressed data rates are on average within 16% of the CCSDS standard. In scenarios where energy constraints can be relaxed, CCSDS 123.0-B-2 yields the best average compression results of all evaluated methods.

Published
2020

48. DNA Microarray Image Coding

Author

Hern´ndez-Cabronero, Miguel, primary, Munoz-Gomez, Juan, additional, Blanes, Ian, additional, Marcellin, Michael W., additional, and Serra-Sagrista, Joan, additional

Published
2012
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