Color LAR codec : a color image representation and compression scheme based on local resolution adjustment and on self-extracting region representation

This LAR (Locally Adaptive Resolution) color image coding scheme yields to an efficient progressive compression with a better subjective quality than Jpeg2000. Additionally, it offers region functionalities for low bit rate coding and decoding. From highly compressed luminance, a region description, without contours encoding, can be obtained through a segmentation process performed at both coder and decoder. Considering color results, controlled chrominance components segmentation provides a better data consistency simultaneously with a low bit rate compression. As regions and their encoding are based on a same representation grid, enhancement of image quality can be global, or only restricted to a Region Of Interest.Cet article présente un schéma original de codage progressif d'images couleur apportant à la fois une efficacité en termes de compression (meilleure qualité subjective que Jpeg2000) et des fonctionnalités au niveau région à bas débits pour le codeur et le décodeur. À partir de l'image des luminances codée à bas débit par le codec LAR (Locally Adaptive Resolution), une description en régions, sans codage des contours, est obtenue à travers un procédé de segmentation effectué au codeur et au décodeur. Cette segmentation peut être contrôlée par les composantes chromatiques pour une meilleure cohérence du résultat d'un point de vue couleur. Un codage basé régions appliqué sur les images de chrominance produit alors une compression de ces composantes à très bas débit. Comme les régions et le codage de leur contenu partagent une même grille de représentation, l'amélioration de la qualité de l'image peut être globale, ou limitée à une zone d'intérêt

Th1 Disabled Function in Response to TLR4 Stimulation of Monocyte-Derived DC from Patients Chronically-Infected by Hepatitis C Virus

Background: Lack of protective antibodies and inefficient cytotoxic responses are characteristics of chronic hepatitis C infection. A defect in dendritic cell (DC) function has thus been suspected, but this remains a controversial issue. Methods and Findings: Here we show that monocyte-derived DC (MoDC) from chronically-infected patients can mature in response to TLR1/2, TLR2/6 or TLR3 ligands. In contrast, when stimulated with the TLR4 ligand LPS, MoDC from patients show a profound defect in inducing IFNc secretion by allogeneic T cells. This defect is not due to defective phenotypic maturation or to the presence of HCV-RNA in DC or monocytes but is correlated to reduced IL-12 secretion by DC. Restoration of DC ability to stimulate IFNc secretion can be obtained by blocking MEK activation in DC, indicating that MEK/ ERK pathway is involved in the Th1 defect of MoDC. Monocytes from HCV patients present increased spontaneous secretion of cytokines and chemokines, especially MIP-1b. Addition of MIP-1b on healthy monocytes during differentiation results in DC that have Th1 defect characteristic of MoDC from HCV patients, suggesting that MIP-1b secretion by HCV monocytes participates in the Th1 defect of DC. Conclusions: Our data indicate that monocytes from HCV patients are activated in vivo. This interferes with their differentiation into DC, leading to deficient TLR4 signaling in these cells that are enable to induce a Th1 response. Thi

Human cell types important for Hepatitis C Virus replication in vivo and in vitro. Old assertions and current evidence

Hepatitis C Virus (HCV) is a single stranded RNA virus which produces negative strand RNA as a replicative intermediate. We analyzed 75 RT-PCR studies that tested for negative strand HCV RNA in liver and other human tissues. 85% of the studies that investigated extrahepatic replication of HCV found one or more samples positive for replicative RNA. Studies using in situ hybridization, immunofluorescence, immunohistochemistry, and quasispecies analysis also demonstrated the presence of replicating HCV in various extrahepatic human tissues, and provide evidence that HCV replicates in macrophages, B cells, T cells, and other extrahepatic tissues. We also analyzed both short term and long term in vitro systems used to culture HCV. These systems vary in their purposes and methods, but long term culturing of HCV in B cells, T cells, and other cell types has been used to analyze replication. It is therefore now possible to study HIV-HCV co-infections and HCV replication in vitro

Performance and Computational Complexity of the Future Video Coding

International audienceThe drastic increasing of multimedia applications, such as IPTV, Virtual Reality (VR, 360°) and Light Field videos has led to a high computing complexity in video compression and content quality assessment. In the last five years, HEVC standard has been widely used in the industrial community due to its bit-rate gain compared to its predecessor H.264/AVC. Recently, a new coding tools have been developed under the Joint Exploration Model (JEM) software, with the main goal to provide high bit rate saving compared to the HEVC standard. In this paper we investigate the performance and the associated computational complexity of these emerging video coding tools, from both encoding and decoding sides. Two spatial resolutions (HD 4K) and several video contents have been used in this study. Results have shown that despite the bit-rate saving, a considerable computational complexity can be noticed. A bit-rate saving up to 37% and quality enhancements up to 30% can be achieved by JEM. However, these emerging tools are time consuming between x5 and x12 times compared to the HM reference software, depending on video sequence and encoding/decoding processes. © 2018 IEEE