Search results for "Image processing"

Stratified Autocalibration of Cameras with Euclidean Image Plane

2020

International audience; This paper tackles the problem of stratified autocalibration of a moving camera with Euclidean image plane (i.e. zero skew and unit aspect ratio) and constant intrinsic parameters. We show that with these assumptions, in addition to the polynomial derived from the so-called modulus constraint, each image pair provides a new quartic polynomial in the unknown plane at infinity. For three or more images, the plane at infinity estimation is stated as a constrained polynomial optimization problem that can efficiently be solved using Lasserre's hierarchy of semidefinite relaxations. The calibration parameters and thus a metric reconstruction are subsequently obtained by so…

Implémentation en temps réel d'une architecture embarquée pour le comptage de passagers dans le transport public

2018

Automatisation de l'évaluation de la Fraîcheur des produits de la mer par imagerie couleur

2002

Real-time implementation of counting people in a crowd on the embedded reconfigurable architecture on the unmanned aerial vehicle

2020

The crowd counting task is an important research problem. Now more and more people are concerned about safety issues. Considering the scenario of a crowded scene: a population density system analyzes the crowds and triggers a warning to divert the crowds when their population density exceeds a normal range. With such a system, the incident of the Shanghai New Year's stampede will not happen again. The most difficult problem of population counting at present: On the one hand, in the densely populated area, how to make the model distinguish human head features more finely, such as head overlap. The second aspect is to find a small-scale local head feature in an image with a wide range of popu…

Non conventional Imaging Systems for 3D Digitization of transparent and/or specular manufactured objects

2013

International audience; 3D scanning has been investigated for several years and most of the proposed approaches assume a diffuse or near diffuse reflectance of the object's surface, also called cooperative surfaces. For the case of "non cooperative surfaces", such as transparent objects or mirror-like surfaces, usually, a thin layer of powder is sprayed onto the object surface (to make it opaque and diffuse) prior to its digitization. This extra step is troublesome, time consuming (the object needs to be cleaned afterwards), and the final accuracy is often dependent on the powder thickness and its homogeneousness. To avoid this step, various methods have been investigated over the last few …

A reference free approach for the comparative evaluation of eight segmentation methods for the estimation of the left ventricular ejection fraction i…

2012

International audience; Objective evaluation and comparison of segmentation algorithms for medical imaging is still a challenging issue. The most frequently used evaluation method consists in comparing the segmentation with a manual delineation. Since obtaining such manual segmentation can be tedious, we proposed a method based on the "extended Regression Without Truth" approach (eRWT)(1). This approach is applied to the comparative evaluation of 8 segmentation algorithms with different degrees of automation from the estimated left ventricular ejection fraction (LVEF).

Perspective-n-Learned-Point: Pose Estimation from Relative Depth

2019

International audience; In this paper we present an online camera pose estimation method that combines Content-Based Image Retrieval (CBIR) and pose refinement based on a learned representation of the scene geometry extracted from monocular images. Our pose estimation method is two-step, we first retrieve an initial 6 Degrees of Freedom (DoF) location of an unknown-pose query by retrieving the most similar candidate in a pool of geo-referenced images. In a second time, we refine the query pose with a Perspective-n-Point (PnP) algorithm where the 3D points are obtained thanks to a generated depth map from the retrieved image candidate. We make our method fast and lightweight by using a commo…

Implémentation en temps réel d'une architecture embarquée pour le comptage de personnes dans une foule

2018

International audience

TRAITEMENT NUMÉRIQUE D'IMAGES ET APPLICATIONS: Méthodes statistiques optimisées pour le traitement numérique des images de grandes tailles,

2010

Automatic Detection of Cerebral Microbleed in SWI Using Radon Transform

2013

International audience; Since presence and number of cerebral microbleeds (CMBs) have come to attention as a potential biomarker, an automated scheme to improve visualization is required. In this work, a new approach of CMB identification in SWIs is presented and compared to visual rating. The method relies on two main steps: a 3D anisotropic multi-scale approach that extracts size and centre of all potential CMBs within the image, and feature extraction using the Radon Transform for final classification using a random forest classifier. The novelty of the technique consists in combining Radon transform and multiscale analysis to obtain robust feature descriptors.