The Experts below are selected from a list of 264342 Experts worldwide ranked by ideXlab platform

H Clenet - One of the best experts on this subject based on the ideXlab platform.

  • a systematic mapping procedure based on the modified Gaussian Model to characterize magmatic units from olivine pyroxenes mixtures application to the syrtis major volcanic shield on mars
    Journal of Geophysical Research, 2013
    Co-Authors: H Clenet, P Pinet, Y Daydou, Georges Ceuleneer, F Heuripeau
    Abstract:

    Clenet et al. (2011) have developed an adapted version of the Modified Gaussian Model (MGM). The improvements allow the characterization of spectra of olivine-pyroxene(s) mixtures, addressing both modal composition and individual minerals chemical composition. This version of MGM is fully automated and operational with large amounts of hyperspectral imaging data. Two natural cases are considered. The first one is the Sumail massif in the Oman ophiolite (Earth). Based on our approach applied to HyMap data, two contrasted lithologic units are mapped: the mantle, which is harzburgite dominated, and the crust made of gabbros and clinopyroxene-rich cumulates, with spectral variations interpreted in terms of pyroxenes chemical compositions. Once this new MGM mapping approach has been validated on a controlled natural situation, we map the distribution of mafic assemblages across the Syrtis Major volcano on Mars using a visible and near-infrared (VNIR) - short wave infrared (SWIR) Observatoire pour la mineralogie, l'eau, les glaces et l'activite (OMEGA) / Mars Express (MEx) mosaic. Our results are in agreement with previous work but olivine appears to be more abundant than previously estimated in the central part of the volcanic edifice, especially in ternary mafic assemblages (augite, olivine, enstatite). Based on these results, we propose a possible scenario for the igneous (and thus thermal) evolution of the Syrtis Major region. Surrounding terrains have formed first and local heterogeneity can be observed between northern and southern areas of the Noachian crust. We also observe variations in the mineral assemblages within Syrtis Major lavas, which can be interpreted in terms of differentiation from a common parent melt and/or of a progressive evolution of the mantle source composition and temperature. Key Points MGM systematic mapping on Syrtis Major to characterize mafic minerals mixtures Olivine and pyroxenes mixture is detected in the central lavas of the volcano Pyroxenes have chemical compositions spanning the enstatite-augite range

  • a new systematic approach using the modified Gaussian Model insight for the characterization of chemical composition of olivines pyroxenes and olivine pyroxene mixtures
    Icarus, 2011
    Co-Authors: H Clenet, P Pinet, Y Daydou, F Heuripeau, Christine Rosemberg
    Abstract:

    An automatic procedure has been implemented on the original MGM approach (Sunshine et al., 1990) in order to deal with an a priori unknown mafic mineralogy observed in the visible-near infrared by reflectance spectroscopy in the case of laboratory or natural rock spectra. We consider all the mixture possibilities involving orthopyroxene, clinopyroxene and olivine, and use accordingly for each configuration different numbers of Gaussians, depending on the potential complexity of the mixture. A key issue is to initialize the MGM procedure with a proper setting for the Gaussians parameters. An automatic analysis of the shape of the spectrum is first performed. The continuum is handled with a second order polynomial adjusted on the local maxima along the spectrum and Gaussians parameters initial settings are made on the basis of laboratory results available in the literature in the case of simple mixtures of mafic minerals. The returned MGM solutions are then assessed on spectroscopic grounds and either validated or discarded, on the basis of a mineralogical sorting. The results presented in this paper are a first quantitative step to characterize both modal and chemical compositions of pyroxenes and olivines. A demonstration of the methodology on specific examples of binary and ternary olivine-pyroxenes mixtures has been made, which shows that the different non-linear effects which affect the Gaussian parameters (center and strength) can be successfully handled. Of note is the fact that the band center positions associated with the different mafic minerals are not set here in the inverse problem, and thus the MGM outputs are truly informative of the chemical composition of pyroxenes and olivines. With the consideration of some limits on the detection thresholds, these results are quite promising for increasing the operational use of the Modified Gaussian Model with large hyperspectral data sets in view of establishing detailed mineralogical mappings of magmatic units.

Min-cheol Hong - One of the best experts on this subject based on the ideXlab platform.

  • a modified Gaussian Model based low complexity pre processing algorithm for h 264 video coding standard
    The Journal of Korean Institute of Communications and Information Sciences, 2005
    Co-Authors: Wonseon Song, Min-cheol Hong
    Abstract:

    In this paper, we present a low complexity modified Gaussian Model based pre-processing filter to improve the performance of H.264 compressed video. Video sequence captured by general imaging system represents the degraded version due to the additive noise which decreases coding efficiency and results in unpleasant coding artifacts due to higher frequency components. By incorporating local statistics and quantization parameter into filtering process, the spurious noise is significantly attenuated and coding efficiency is improved for given quantization step size. In addition, in order to reduce the complexity of the pre-processing filter, the simplified local statistics and quantization parameter are introduced. The simulation results show the capability of the proposed algorithm.

  • a modified Gaussian Model based low complexity pre processing algorithm for h 264 video coding standard
    Lecture Notes in Computer Science, 2004
    Co-Authors: Wonseon Song, Min-cheol Hong
    Abstract:

    In this paper, we present a low complexity modified Gaussian Model-based pre-processing filter to improve the performance of H.264 compressed video. Noisy video sequences captured by imaging system result in decline of coding efficiency and unpleasant coding artifacts due to higher frequency components. By incorporating local statistics and quantization parameter into filtering process, the spurious noise is significantly attenuated and coding efficiency is improved, leading to improvement of visual quality and to bit-rate saving for given quantization step size. In addition, in order to reduce the complexity of the pre-processing filter, the simplified local statistics and quantization parameter induced by analyzing H.264 transformation and quantization processes are introduced. The simulation results show the capability of the proposed algorithm.

Tulay Adali - One of the best experts on this subject based on the ideXlab platform.

  • complex valued independent vector analysis application to multivariate Gaussian Model
    Signal Processing, 2012
    Co-Authors: Matthew Anderson, Tulay Adali
    Abstract:

    We consider the problem of joint blind source separation of multiple datasets and introduce a solution to the problem for complex-valued sources. We pose the problem in an independent vector analysis (IVA) framework and provide a new general IVA implementation using Wirtinger calculus and a decoupled nonunitary optimization algorithm to facilitate Newton-based optimization. Utilizing the noncircular multivariate Gaussian distribution as a source prior enables the full utilization of the complete second-order statistics available in the covariance and pseudo-covariance matrices. The algorithm provides a principled approach for achieving multiset canonical correlation analysis.

  • joint blind source separation with multivariate Gaussian Model algorithms and performance analysis
    IEEE Transactions on Signal Processing, 2012
    Co-Authors: Matthew Anderson, Tulay Adali
    Abstract:

    In this paper, we consider the joint blind source separation (JBSS) problem and introduce a number of algorithms to solve the JBSS problem using the independent vector analysis (IVA) framework. Source separation of multiple datasets simultaneously is possible when the sources within each and every dataset are independent of one another and each source is dependent on at most one source within each of the other datasets. In addition to source separation, the IVA framework solves an essential problem of JBSS, namely the identification of the dependent sources across the datasets. We propose to use the multivariate Gaussian source prior to achieve JBSS of sources that are linearly dependent across datasets. Analysis within the paper yields the local stability conditions, nonidentifiability conditions, and induced Cramer-Rao lower bound on the achievable interference to source ratio for IVA with multivariate Gaussian source priors. Additionally, by exploiting a novel nonorthogonal decoupling of the IVA cost function we introduce both Newton and quasi-Newton optimization algorithms for the general IVA framework.

  • nonorthogonal independent vector analysis using multivariate Gaussian Model
    International Conference on Latent Variable Analysis and Signal Separation, 2010
    Co-Authors: Matthew Anderson, Tulay Adali
    Abstract:

    We consider the problem of joint blind source separation of multiple datasets and introduce an effective solution to the problem. We pose the problem in an independent vector analysis (IVA) framework utilizing the multivariate Gaussian source vector distribution. We provide a new general IVA implementation using a decoupled nonorthogonal optimization algorithm and establish the connection between the new approach and another approach using second-order statistics, multiset canonical correlation analysis. Experimental results are given to demonstrate the success of the new algorithm in achieving reliable source separation for both Gaussian and non-Gaussian sources.

Wonseon Song - One of the best experts on this subject based on the ideXlab platform.

  • a modified Gaussian Model based low complexity pre processing algorithm for h 264 video coding standard
    The Journal of Korean Institute of Communications and Information Sciences, 2005
    Co-Authors: Wonseon Song, Min-cheol Hong
    Abstract:

    In this paper, we present a low complexity modified Gaussian Model based pre-processing filter to improve the performance of H.264 compressed video. Video sequence captured by general imaging system represents the degraded version due to the additive noise which decreases coding efficiency and results in unpleasant coding artifacts due to higher frequency components. By incorporating local statistics and quantization parameter into filtering process, the spurious noise is significantly attenuated and coding efficiency is improved for given quantization step size. In addition, in order to reduce the complexity of the pre-processing filter, the simplified local statistics and quantization parameter are introduced. The simulation results show the capability of the proposed algorithm.

  • a modified Gaussian Model based low complexity pre processing algorithm for h 264 video coding standard
    Lecture Notes in Computer Science, 2004
    Co-Authors: Wonseon Song, Min-cheol Hong
    Abstract:

    In this paper, we present a low complexity modified Gaussian Model-based pre-processing filter to improve the performance of H.264 compressed video. Noisy video sequences captured by imaging system result in decline of coding efficiency and unpleasant coding artifacts due to higher frequency components. By incorporating local statistics and quantization parameter into filtering process, the spurious noise is significantly attenuated and coding efficiency is improved, leading to improvement of visual quality and to bit-rate saving for given quantization step size. In addition, in order to reduce the complexity of the pre-processing filter, the simplified local statistics and quantization parameter induced by analyzing H.264 transformation and quantization processes are introduced. The simulation results show the capability of the proposed algorithm.

F Heuripeau - One of the best experts on this subject based on the ideXlab platform.

  • a systematic mapping procedure based on the modified Gaussian Model to characterize magmatic units from olivine pyroxenes mixtures application to the syrtis major volcanic shield on mars
    Journal of Geophysical Research, 2013
    Co-Authors: H Clenet, P Pinet, Y Daydou, Georges Ceuleneer, F Heuripeau
    Abstract:

    Clenet et al. (2011) have developed an adapted version of the Modified Gaussian Model (MGM). The improvements allow the characterization of spectra of olivine-pyroxene(s) mixtures, addressing both modal composition and individual minerals chemical composition. This version of MGM is fully automated and operational with large amounts of hyperspectral imaging data. Two natural cases are considered. The first one is the Sumail massif in the Oman ophiolite (Earth). Based on our approach applied to HyMap data, two contrasted lithologic units are mapped: the mantle, which is harzburgite dominated, and the crust made of gabbros and clinopyroxene-rich cumulates, with spectral variations interpreted in terms of pyroxenes chemical compositions. Once this new MGM mapping approach has been validated on a controlled natural situation, we map the distribution of mafic assemblages across the Syrtis Major volcano on Mars using a visible and near-infrared (VNIR) - short wave infrared (SWIR) Observatoire pour la mineralogie, l'eau, les glaces et l'activite (OMEGA) / Mars Express (MEx) mosaic. Our results are in agreement with previous work but olivine appears to be more abundant than previously estimated in the central part of the volcanic edifice, especially in ternary mafic assemblages (augite, olivine, enstatite). Based on these results, we propose a possible scenario for the igneous (and thus thermal) evolution of the Syrtis Major region. Surrounding terrains have formed first and local heterogeneity can be observed between northern and southern areas of the Noachian crust. We also observe variations in the mineral assemblages within Syrtis Major lavas, which can be interpreted in terms of differentiation from a common parent melt and/or of a progressive evolution of the mantle source composition and temperature. Key Points MGM systematic mapping on Syrtis Major to characterize mafic minerals mixtures Olivine and pyroxenes mixture is detected in the central lavas of the volcano Pyroxenes have chemical compositions spanning the enstatite-augite range

  • a new systematic approach using the modified Gaussian Model insight for the characterization of chemical composition of olivines pyroxenes and olivine pyroxene mixtures
    Icarus, 2011
    Co-Authors: H Clenet, P Pinet, Y Daydou, F Heuripeau, Christine Rosemberg
    Abstract:

    An automatic procedure has been implemented on the original MGM approach (Sunshine et al., 1990) in order to deal with an a priori unknown mafic mineralogy observed in the visible-near infrared by reflectance spectroscopy in the case of laboratory or natural rock spectra. We consider all the mixture possibilities involving orthopyroxene, clinopyroxene and olivine, and use accordingly for each configuration different numbers of Gaussians, depending on the potential complexity of the mixture. A key issue is to initialize the MGM procedure with a proper setting for the Gaussians parameters. An automatic analysis of the shape of the spectrum is first performed. The continuum is handled with a second order polynomial adjusted on the local maxima along the spectrum and Gaussians parameters initial settings are made on the basis of laboratory results available in the literature in the case of simple mixtures of mafic minerals. The returned MGM solutions are then assessed on spectroscopic grounds and either validated or discarded, on the basis of a mineralogical sorting. The results presented in this paper are a first quantitative step to characterize both modal and chemical compositions of pyroxenes and olivines. A demonstration of the methodology on specific examples of binary and ternary olivine-pyroxenes mixtures has been made, which shows that the different non-linear effects which affect the Gaussian parameters (center and strength) can be successfully handled. Of note is the fact that the band center positions associated with the different mafic minerals are not set here in the inverse problem, and thus the MGM outputs are truly informative of the chemical composition of pyroxenes and olivines. With the consideration of some limits on the detection thresholds, these results are quite promising for increasing the operational use of the Modified Gaussian Model with large hyperspectral data sets in view of establishing detailed mineralogical mappings of magmatic units.