Search results for "Contrast"

Camera-based measurement of relative image contrast in projection displays

2013

International audience; This research investigated the measured contrast of projection displays based on pictures taken by un-calibrated digital cameras under typical viewing conditions. A high-end radiometer was employed as a reference to the physical response of projection luminance. Checkerboard, gray scale and color complex test images with a range of the projector's brightness and contrast settings were projected. Two local and two global contrast metrics were evaluated on the acquired pictures. We used contrast surface plots and Pearson correlation to investigate the measured contrast versus the projector's brightness and contrast settings. The results suggested, as expected, the proj…

A combination of algebraic, geometric and numerical methods in the contrast problem by saturation in magnetic resonance imaging

2014

In this article, the contrast imaging problem by saturation in nuclear magnetic resonance is modeled as a Mayer problem in optimal control. The optimal solution can be found as an extremal solution of the Maximum Principle and analyzed with the recent advanced techniques of geometric optimal control. This leads to a numerical investigation based on shooting and continuation methods implemented in the HamPath software. The results are compared with a direct approach to the optimization problem and implemented within the Bocop toolbox. In complement lmi techniques are used to estimate a global optimum. It is completed with the analysis of the saturation problem of an ensemble of spin particle…

Inverse Tone Mapping Based upon Retina Response

2014

International audience; The development of high dynamic range (HDR) display arouses the research of inverse tone mapping methods, which expand dynamic range of the low dynamic range (LDR) image to match that of HDR monitor. This paper proposed a novel physiological approach, which could avoid artifacts occurred in most existing algorithms. Inspired by the property of the human visual system (HVS), this dynamic range expansion scheme performs with a low computational complexity and a limited number of parameters and obtains high-quality HDR results. Comparisons with three recent algorithms in the literature also show that the proposed method reveals more important image details and produces …

Analysis of fluorescent MRI contrast agent behavior in the liver and thoracic aorta of mice.

2004

To characterize the behavior of magnetofluorescent products injected in mice intravenously.The magnetic resonance imaging (MRI) products were labelled with fluorescent molecules to examine the biodistribution process in vivo and observe them at the cellular level by means of confocal microscopy. Three-dimensional (3D) sequences of images were obtained by spectral analysis of sample preparations in a multiphoton confocal microscope and analyzed by the factor analysis of medical image sequence algorithm, which provides factor curves. Factor images are the result of image-processing methods that utilize information from emission spectra. Preparations are also screened in the counting mode to p…

Modular Assembly of Multimodal Imaging Agents through an Inverse Electron Demand Diels–Alder Reaction

2019

International audience; The combination of two imaging probes on a same biomolecule gives access to targeted bimodal imaging agents that can provide more accurate diagnosis, complementary information, or that may be used in different applications, such as PET imaging and fluorescence imagingassisted surgery. In this study, we demonstrate that dichlorotetrazine, a small, commercially available compound, can be used as a modular platform to easily assemble various imaging probes. Doubly-labeled tetrazines can then be conjugated to a protein through a biorthogonal IEDDA reaction. A series of difunctionalized tetrazine compounds containing various chelating agents and fluorescent dyes was synth…

Article est-il un concept intuitif?

2012

L'intuition représente l'innéisme du courant générativiste ou la vision du monde des cognitivistes. Le cadre cognitiviste permet d'appliquer la notion d'intuition à l'article en français. Un locuteur francophone confirmé ne conçoit jamais un nom sans article. Notre recherche contrastive français-croate traite l'article en tant que concept au niveau sémantique. Le choix d'une langue slave s'impose par l'absence de tout article, en renforçant ainsi le bien-fondé d'une étude axée sur l'intuition. L'analyse part du locuteur et non de la langue en tant que système dans lequel il est immergé. La question est de savoir si le concept est représenté par deux formes différentes dans les deux langues …

« Tous des traitres ! ». Faux-amis, métaphores et illusion référentielle dans la traduction anglais-français : sémantique lexicale et facteurs discur…

2022

Geometric optimal control : homotopic methods and applications

2012

This work is about geometric optimal control applied to celestial and quantum mechanics. We first dealt with the minimum fuel consumption problem of transfering a satellite around the Earth. This brought to the creation of the code HamPath which permits first of all to solve optimal control problem for which the command law is smooth. It is based on the Pontryagin Maximum Principle (PMP) and on the notion of conjugate point. This program combines shooting method, differential homotopic methods and tools to compute second order optimality conditions. Then we are interested in quantum control. We study first a system which consists in two different particles of spin 1/2 having two different r…

Risposta al trattamento mediante ablazione percutanea con radiofrequenza dell’epatocarcinoma: valutazione tramite ecografia con mezzo di contrasto (C…

2008

A Robust Multi Stage Technique for Image Binarization of Degraded Historical Documents

2017

International audience; Document image binarization is a central problem in many document analysis systems. Indeed, it represents one of the basic challenges, especially in case of historical documents analysis. In this paper, we propose a novel robust multi stage framework that combines different existing document image thresholding methods for the purpose of getting a better binarization result. CLAHE technique is introduced to significantly enhance contrast in some poor images. The proposed method then uses a hybrid algorithm to partition image into foreground and background. A special procedure is finally applied in order to remove small noise and correct characters morphology. Experime…