Projection distortion analysis for flattened image mosaicing from straight uniform generalized cylinders

This paper presents a new approach for reconstructing images mapped or painted on straight uniform generalized cylinders (SUGC). A set of monocular images is taken from different viewpoints in order to be mosaiced and to represent the entire scene in detail. The expressions of the SUGC's projection axis are derived from two cross-sections projected onto the image plane. Based on these axes we derive the SUGC localization in the camera coordinate system. We explain how we can find a virtual image representation when the intersection of the two axes is matched to the image center. We analyze the perspective distortions when flattening a scene which is mapped on a SUGC. We evaluate the lower and the upper bounds of the necessary number of views in order to represent the entire scene from a SUGC, by considering the distortions produced by perspective projection. A region matching based mosaicing method is proposed to be applied on the flattened images in order to obtain the complete scene. The mosaiced scene is visualized on a new synthetic surface by a mapping procedure. The proposed algorithm is used for the representation of mural paintings located on SUGCs with closed cross-sections (circles for columns), or opened cross-sections (ellipses or parabolas for vaults). (C) 2001 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved

Scalable Video Coding

International audienceWith the evolution of Internet to heterogeneous networks both in terms of processing power and network bandwidth, different users demand the different versions of the same content. This has given birth to the scalable era of video content where a single bitstream contains multiple versions of the same video content which can be different in terms of resolutions, frame rates or quality. Several early standards, like MPEG2 video, H.263, and MPEG4 part II already include tools to provide different modalities of scalability. However, the scalable profiles of these standards are seldom used. This is because the scalability comes with significant loss in coding efficiency and the Internet was at its early stage. Scalable extension of H.264/AVC is named scalable video coding and is published in July 2007. It has several new coding techniques developed and it reduces the gap of coding efficiency with state-of-the-art non-scalable codec while keeping a reasonable complexity increase. After an introduction to scalable video coding, we present a proposition regarding the scalable functionality of H.264/AVC, which is the improvement of the compression ratio in enhancement layers (ELs) of subband/wavelet based scalable bitstream. A new adaptive scanning methodology for intra frame scalable coding framework based on subband/wavelet coding approach is presented for H.264/AVC scalable video coding. It takes advantage of the prior knowledge of the frequencies which are present in different higher frequency subbands. Thus, by just modification of the scan order of the intra frame scalable coding framework of H.264/AVC, we can get better compression, without any compromise on PSNR

Quantization Watermarking for Joint Compression and Data Hiding Schemes

International audienceEnrichment and protection of JPEG2000 images is an important issue. Data hiding techniques are a good solution to solve these problems. In this context, we can consider the joint approach to introduce data hiding technique into JPEG2000 coding pipeline. Data hiding consists of imperceptibly altering multimedia content, to convey some information. This process is done in such a way that the hidden data is not perceptible to an observer. Digital watermarking is one type of data hiding. In addition to the imperceptibility and payload constraints, the watermark should be robust against a variety of manipulations or attacks. We focus on trellis coded quantization (TCQ) data hiding techniques and propose two JPEG2000 compression and data hiding schemes. The properties of TCQ quantization, defined in JPEG2000 part 2, are used to perform quantization and information embedding during the same time. The first scheme is designed for content description and management applications with the objective of achieving high payloads. The compression rate/imperceptibility/payload trade off is our main concern. The second joint scheme has been developed for robust watermarking and can have consequently many applications. We achieve the better imperceptibility/robustness trade off in the context of JPEG2000 compression. We provide some experimental results on the implementation of these two schemes

Oxford SWIFT IFS and multi-wavelength observations of the Eagle galaxy at z=0.77

The `Eagle' galaxy at a redshift of 0.77 is studied with the Oxford Short Wavelength Integral Field Spectrograph (SWIFT) and multi-wavelength data from the All-wavelength Extended Groth strip International Survey (AEGIS). It was chosen from AEGIS because of the bright and extended emission in its slit spectrum. Three dimensional kinematic maps of the Eagle reveal a gradient in velocity dispersion which spans 35-75 +/- 10 km/s and a rotation velocity of 25 +/- 5 km/s uncorrected for inclination. Hubble Space Telescope images suggest it is close to face-on. In comparison with galaxies from AEGIS at similar redshifts, the Eagle is extremely bright and blue in the rest-frame optical, highly star-forming, dominated by unobscured star-formation, and has a low metallicity for its size. This is consistent with its selection. The Eagle is likely undergoing a major merger and is caught in the early stage of a star-burst when it has not yet experienced metal enrichment or formed the mass of dust typically found in star-forming galaxies.Comment: accepted for publication in MNRA

Looking At the Distant Universe with the MeerKAT Array (LADUMA)

The MeerKAT (64 x 13.5m dish radio interferometer) is South Africa's precursor instrument for the Square Kilometre Array (SKA), exploring dish design, instrumentation, and the characteristics of a Karoo desert site and is projected to be on sky in 2016. One of two top-priority, Key Projects is a single deep field, integrating for 5000 hours total with the aim to detect neutral atomic hydrogen through its 21 cm line emission out to redshift unity and beyond. This first truly deep HI survey will help constrain fueling models for galaxy assembly and evolution. It will measure the evolution of the cosmic neutral gas density and its distribution over galaxies over cosmic time, explore evolution of the gas in galaxies, measure the Tully-Fisher relation, measure OH maser counts, and address many more topics. Here we present the observing strategy and envisaged science case for this unique deep field, which encompasses the Chandra Deep Field-South (and the footprints of GOODS, GEMS and several other surveys) to produce a singular legacy multi-wavelength data-set.Comment: 3 pages, 2 figures, to appear in the proceedings of IAU Symposium 284, "The Spectral Energy Distribution of Galaxies" (SED2011), 5-9 September 2011, Preston, UK, editors R.J. Tuffs & C.C.Popesc

Safe Transfert of Medical Images by Conjoined Coding : Selective Encryption by AES Using the Stream Cipher Mode OFB and JPEG Compression

The traffic of digital images has increased rapidly in the wide networks. The protection of this kind of data becomes important for many reasons such as confidentiality, obscurity and security. Nowadays, the most important engine to provide confidentiality is encryption. Therefore, the classical and modern ciphers are not suitable for such huge quantity of data in real-time environment. Selective encryption (SE) is an approach to encode a portion of the data in order to reduce computational requirements and to provide a proportional privacy. This paper presents a new method of partial or selective encryption for JPEG images. It is based on encoding of some Huffman bitstream with AES cipher. The proposed method results in a significant reduction in encrypting and decrypting processing time, provides a constant bit rate and keeps the JPEG bitstream compliance.Le trafic des images numériques augmente rapidement sur les réseaux. La protection des données numériques, et en particulier les images médicales, devient importante pour de nombreuses raisons telles que la confidentialité et l'intégrité. Actuellement, la façon la plus répandue de répondre au problème de la confidentialité est le cryptage. Cependant, les algorithmes classiques et modernes de chiffrement ne sont pas capables de chiffrer une énorme quantité de données dans un environnement en temps réel. Le cryptage sélectif (CS) est une approche qui ne chiffre qu'une partie des données afin de diminuer le temps de calcul tout en assurant une certaine sécurité. Cet article présente une nouvelle méthode de cryptage sélectif pour des images médicales comprimées au format JPEG. Cette méthode est basée sur le cryptage par flot avec AES d'une partie du flux binaire issue du codage par Huffman. Les résultats de la méthode proposée présentent un gain de temps de calcul significatif tout en conservant le taux de compression et le format initial de JPEG

EAGLE multi-object AO concept study for the E-ELT

EAGLE is the multi-object, spatially-resolved, near-IR spectrograph instrument concept for the E-ELT, relying on a distributed Adaptive Optics, so-called Multi Object Adaptive Optics. This paper presents the results of a phase A study. Using 84x84 actuator deformable mirrors, the performed analysis demonstrates that 6 laser guide stars and up to 5 natural guide stars of magnitude R<17, picked-up in a 7.3' diameter patrol field of view, allow us to obtain an overall performance in terms of Ensquared Energy of 35% in a 75x75 mas^2 spaxel at H band, whatever the target direction in the centred 5' science field for median seeing conditions. The computed sky coverage at galactic latitudes |b|~60 is close to 90%.Comment: 6 pages, to appear in the proceedings of the AO4ELT conference, held in Paris, 22-26 June 200

Pressure Evolution of the Magnetic Field induced Ferromagnetic Fluctuation through the Pseudo-Metamagnetism of CeRu2Si2

Resistivity measurements performed under pressure in the paramagnetic ground state of CeRu2Si2 are reported. They demonstrate that the relative change of effective mass through the pseudo metamagnetic transition is invariant under pressure. The results are compared with the first order metamagnetic transition due to the antiferromagnetism of Ce0.9La0.1Ru2Si2 which corresponds to the "negative" pressure of CeRu2Si2 by volume expansion. Finally, we describe the link between the spin-depairing of quasiparticles on CeRu2Si2 and that of Cooper pairs on the unconventional heavy fermion superconductor CeCoIn5.Comment: 5 pages, 6 figures, accepted for publication in J. Phys. Soc. Jp

One Dimensional Hybrid-Vlasov Simulation of a Hall Thruster

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97103/1/AIAA2012-4313.pd