Segmentation d'images par comparaison d'histogrammes de lois d'innovations

Nous proposons, dans ce papier, une méthode de détection de changements de modèles à partir de modélisations de type AR par la comparaison d'histogrammes approchant des lois de probabilité dont le nombre de classes est déterminé par différents critères d'information. Ces critères ont été initialement développés pour la sélection d'ordre de modèles ou pour des techniques de codage, et sont ici reformulés pour être appliqués aux histogrammes. Le support est constitué de fichiers images issus de photographies comportant des zones de caractères à localiser. Il s'agit de différencier les zones de fond des zones de caractères par comparaisons des histogrammes de leur loi d'innovation respective

Evolution d'etat non-lineaire et filtrage approche par maximum d'entropie

La détermination de l'état d'un système après observation s'effectue usuellement par le filtre de Kalman. Pour une évolution d'état non linéaire,cette méthode ne peut pas être appliquée. L'observation linéaire est la somme d'un bruit de loi exponentielle,et d'un état de loi conditionnelle, indépendante, approchée exponentielle. L'équation d'état non-linéaire permet l'approximation numérique par maximum d'entropie sous contraintes linéaires de la loi de l'état prédit sous la forme exponentielle. Ainsi des distributions probabilistes multi-modales peuvent être introduites

Underwater color constancy: enhancement of automatic live fish recognition

We present in this paper some advances in color restoration of underwater images, especially with regard to the strong and non uniform color cast which is typical of underwater images. The proposed color correction method is based on ACE model, an unsupervised color equalization algorithm. ACE is a perceptual approach inspired by some adaptation mechanisms of the human visual system, in particular lightness constancy and color constancy. A perceptual approach presents a lot of advantages: it is unsupervised. robust and has local filtering properties, that lead to more effective results. The restored images give better results when displayed or processed (fish segmentation and feature extraction). The presented preliminary results are satisfying and promising

Subtoxic concentrations of allergenic haptens induce LC migration and maturation in a human organotypic skin explant culture model: A novel method for identifying potential contact allergens

The accelerated migration of Langerhans cells (LCs) out of the epidermis and up-regulation of maturation markers, upon treatment with subtoxic concentrations of chemicals, were used as the criteria to determine the potential of allergenic chemicals capable of inducing a hapten-specific delayed-type hypersensitivity reaction. Here we report the findings of a study in which seven chemicals, coded and tested in a blind fashion, were classified as contact allergens or non-allergens using the human organotypic skin explant culture (hOSEC) model. All chemicals that were identified as a contact sensitizer on decoding induced a definite decrease in the number of CD1a and HLA-DR-positive epidermal LCs in the epidermis of the skin explants, as determined by both semiquantitative immunohistochemistry and quantitative flow cytometric analysis. A significant increase in the number of CD83+ cells was accompanied by up-regulation of activation molecules in the epidermis of hOSEC exposed specifically to contact allergens. In contrast, there were only minor alterations in epidermal LC numbers, expression of CD83 and other activation markers by LCs when the biopsies were treated with non-toxic concentrations of non-allergenic irritants and vehicles. The data suggest that an increased epidermal LC migration and maturation accompanied by increased expression of activation markers could be used as end-point determinants to screen allergens in a non-animal alternative hOSEC model. © Blackwell Munksgaard, 2006

Underwater Color Constancy: Enhancement of Automatic Live Fish Recognition

We present in this paper some advances in color restoration of underwater images, especially with regard to the strong and non uniform color cast which is typical of underwater images. The proposed color correction method is based on ACE model, an unsupervised color equalization algorithm. ACE is a perceptual approach inspired by some adaptation mechanisms of the human visual system, in particular lightness constancy and color constancy. A perceptual approach presents a lot of advantages: it is unsupervised, robust and has local filtering properties, that lead to more effective results. The restored images give better results when displayed or processed (fish segmentation and feature extraction). The presented preliminary results are satisfying and promising

Subtoxic concentrations of allergenic haptens induce LC migration and maturation in a human organotypic skin explant culture model: a novel method for identifying potential contact allergens

The accelerated migration of Langerhans cells (LCs) out of the epidermis and up-regulation of maturation markers, upon treatment with subtoxic concentrations of chemicals, were used as the criteria to determine the potential of allergenic chemicals capable of inducing a hapten-specific delayed-type hypersensitivity reaction. Here we report the findings of a study in which seven chemicals, coded and tested in a blind fashion, were classified as contact allergens or non-allergens using the human organotypic skin explant culture (hOSEC) model. All chemicals that were identified as a contact sensitizer on decoding induced a definite decrease in the number of CD1a and HLA-DR-positive epidermal LCs in the epidermis of the skin explants, as determined by both semiquantitative immunohistochemistry and quantitative flow cytometric analysis. A significant increase in the number of CD83(+) cells was accompanied by up-regulation of activation molecules in the epidermis of hOSEC exposed specifically to contact allergens. In contrast, there were only minor alterations in epidermal LC numbers, expression of CD83 and other activation markers by LCs when the biopsies were treated with non-toxic concentrations of non-allergenic irritants and vehicles. The data suggest that an increased epidermal LC migration and maturation accompanied by increased expression of activation markers could be used as end-point determinants to screen allergens in a non-animal alternative hOSEC mode