Christian Daul

Christian Daul
University of Lorraine | UdL · CRAN - Centre de Recherche en Automatique de Nancy

PhD

About

128
Publications
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Publications

Publications (128)
Article
Full-text available
Endoscopy is the most widely used medical technique for cancer and polyp detection inside hollow organs. However, images acquired by an endoscope are frequently affected by illumination artefacts due to the enlightenment source orientation. There exist two major issues when the endoscope's light source pose suddenly changes: overexposed and underex...
Preprint
Endoscopy is the most widely used medical technique for cancer and polyp detection inside hollow organs. However, images acquired by an endoscope are frequently affected by illumination artefacts due to the enlightenment source orientation. There exist two major issues when the endoscope's light source pose suddenly changes: overexposed and underex...
Poster
Full-text available
Deep learning has shown great promise in diverse areas of computer vision, such as image classification, object detection, and semantic segmentation, among many others. However, as it has been repeatedly demonstrated, deep learning methods trained on a dataset do not generalize well to datasets from other domains or even to similar datasets, due to...
Preprint
Full-text available
In this contribution we use an ensemble deep-learning method for combining the prediction of two individual one-stage detectors (i.e., YOLOv4 and Yolact) with the aim to detect artefacts in endoscopic images. This ensemble strategy enabled us to improve the robustness of the individual models without harming their real-time computation capabilities...
Preprint
Full-text available
This contribution presents a deep-learning method for extracting and fusing image information acquired from different viewpoints with the aim to produce more discriminant object features. Our approach was specifically designed to mimic the morpho-constitutional analysis used by urologists to visually classify kidney stones by inspecting the section...
Preprint
Full-text available
Deep learning has shown great promise in diverse areas of computer vision, such as image classification, object detection and semantic segmentation, among many others. However, as it has been repeatedly demonstrated, deep learning methods trained on a dataset do not generalize well to datasets from other domains or even to similar datasets, due to...
Article
ABSTRACT OBJECTIVE To assess the potential of automated machine learning methods for recognizing urinary stones in endoscopy. MATERIALS AND METHODS Surface and section images of 123 urinary calculi (109 ex vivo and 14 in vivo stones), were acquired using ureteroscopes. They were over 85% pure. Six classes of urolithiasis were represented: group...
Preprint
Full-text available
Polyps are well-known cancer precursors identified by colonoscopy. However, variability in their size, location, and surface largely affect identification, localisation, and characterisation. Moreover, colonoscopic surveillance and removal of polyps (referred to as polypectomy ) are highly operator-dependent procedures. There exist a high missed de...
Preprint
Full-text available
Determining the type of kidney stones allows urologists to prescribe a treatment to avoid recurrence of renal lithiasis. An automated in-vivo image-based classification method would be an important step towards an immediate identification of the kidney stone type required as a first phase of the diagnosis. In the literature it was shown on ex-vivo...
Article
Full-text available
Gastric cancer is the second leading cause of cancer-related deaths worldwide. Early diagnosis significantly increases the chances of survival; therefore, improved assisted exploration and screening techniques are necessary. Previously we made use of an augmented multi-spectral endoscope by inserting an optical probe into the instrumentation channe...
Presentation
Full-text available
2021 43rd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) talk "Assessing deep learning methods for the identification of kidney stones in endoscopic images"
Presentation
Full-text available
Assessing deep learning methods for the identification of kidney stones in endoscopic images. F. Lopez, A. Varela, O. Hinojosa, M. Mendez, D.H. Trinh, J. ElBeze, J. Hubert, V. Estrade, M. Gonzalez, G. Ochoa, C. Daul. 2021 43rd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC).
Poster
Full-text available
Knowing the type (i.e., the biochemical composition) of kidney stones is crucial to prevent relapses with an appropriate treatment. During ureteroscopies, kidney stones are fragmented, extracted from the urinary tract, and their composition is determined using a morpho-constitutional analysis. This procedure is time-consuming (the morpho-constituti...
Preprint
Full-text available
Polyps in the colon are widely known as cancer precursors identified by colonoscopy either related to diagnostic work-up for symptoms, colorectal cancer screening or systematic surveillance of certain diseases. Whilst most polyps are benign, the number, size and the surface structure of the polyp are tightly linked to the risk of colon cancer. Ther...
Article
Full-text available
Medical infrared thermography has proven to be a complementary procedure to physiological disorders, such as the diabetic foot. However, the technique remains essentially based on 2D images that display partial anatomy. In this context, a 3D thermal model provides improved visualization and faster inspection. This paper presents a 3D reconstruction...
Preprint
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////Preprint under review for EMBC’21 following IEEE guidelines///////////////////////////// /////////////////////Arxiv Link --> https://arxiv.org/abs/2103.01146////////////////////// ///////////////////////////////////...
Article
Full-text available
The Endoscopy Computer Vision Challenge (EndoCV) is a crowd-sourcing initiative to address eminent problems in developing reliable computer aided detection and diagnosis endoscopy systems and suggest a pathway for clinical translation of technologies. Whilst endoscopy is a widely used diagnostic and treatment tool for hollow-organs, there are sever...
Conference Paper
According to the International Diabetes Federation, approximately four million people die from diabetes each year, and ten million more suffer disabling or potentially terminal complications, such as diabetic foot disease. Therefore, the proposal is the early detection by detecting non-homogeneous temperature regions with radiometric data and image...
Preprint
Full-text available
The Endoscopy Computer Vision Challenge (EndoCV) is a crowd-sourcing initiative to address eminent problems in developing reliable computer aided detection and diagnosis endoscopy systems and suggest a pathway for clinical translation of technologies. Whilst endoscopy is a widely used diagnostic and treatment tool for hollow-organs, there are sever...
Conference Paper
Urolithiasis is a common disease around the world and its incidence has been growing every year. There are various diagnosis techniques based on kidney stone identification aiming to find the formation cause. However, most of them are time consuming, tedious and expensive. The accuracy of the diagnosis is crucial for the prescription of an appropri...
Article
Background The study proposes to improve bladder cancer diagnosis by (i) photodynamic diagnosis (PDD) using red-light excitation (632.8 nm) of 5-ALA induced-protoporphyrin IX in 9 patients’ bladder associated to the analysis of two types of signals to improve the diagnostic accuracy, and (ii) numerical modeling of scattering coefficient for providi...
Book
This volume contains the proceedings of the second edition of the in- ternational workshop and challenge on computer vision in endoscopy- (EndoCV). Due to the COVID-19 outbreak, the workshop was vir- tually held as a webinar on the 3rd Arpil 2020 (initially planned to be held in Iowa, USA). For the second time this challenge was co- located with th...
Article
This paper details a novel optical flow-based structure from motion (SfM) approach for the reconstruction of surfaces with few textures using video sequences acquired under strong illumination changes. An original image search and grouping strategy allows to reconstruct each 3D scene point using a large set of 2D homologous points extracted from a...
Preprint
Full-text available
Whilst many technologies are built around endoscopy, there is a need to have a comprehensive dataset collected from multiple centers to address the generalization issues with most deep learning frameworks. What could be more important than disease detection and localization? Through our extensive network of clinical and computational experts, we ha...
Article
Full-text available
We present a comprehensive analysis of the submissions to the first edition of the Endoscopy Artefact Detection challenge (EAD). Using crowd-sourcing, this initiative is a step towards understanding the limitations of existing state-of-the-art computer vision methods applied to endoscopy and promoting the development of new approaches suitable for...
Article
Full-text available
Whilst many technologies are built around endoscopy, there is a need to have a comprehensive dataset collected from multiple centers to address the generalization issues with most deep learning frameworks. What could be more important than disease detection and localization? Through our extensive network of clinical and computational experts, we ha...
Thesis
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////////////////////////////////////////////////////////////////////////////////////////////////////// ////////////////////////////// For more details about this work please refer to our publication at ////////////////////////////////////////////////////////////////////////////////////////////////////// ///////////////////////////On the in vivo rec...
Article
The current clinical study is aimed at evaluating the clinical relevance of an innovative device (called CyPaM2 device) that for the first time provides urologists with (i) a panoramic image of the bladder inner wall within the surgery time, and with (ii) a simultaneous (bimodal) display of fluorescence and white-light video streams during the fluo...
Conference Paper
Full-text available
In structure from motion (SfM) algorithms, the surface reconstruction performance strongly depends on the quality of the determination of homologous points between images. Classical feature matching-based methods as integrated in the state-of the-art SfM-algorithms are often inoperative for scenes including weak structures and textures (e.g., as th...
Article
Full-text available
Spatially resolved multiply excited autofluorescence spectroscopy is a valuable optical biopsy technique to investigate skin UV-Visible optical properties in vivo in clinics. However, it provides bulk fluorescence signals from which the individual endogenous fluorophore contributions need to be disentangled. Skin optical clearing allows for increas...
Preprint
Full-text available
Endoscopic artifacts are a core challenge in facilitating the diagnosis and treatment of diseases in hollow organs. Precise detection of specific artifacts like pixel saturations, motion blur, specular reflections, bubbles and debris is essential for high-quality frame restoration and is crucial for realizing reliable computer-assisted tools for im...
Article
This paper deals with variational optical flow approaches for motion estimation under varying illumination conditions in weakly textured scenes. It proposes a systematic and complete study on descriptor-based data-terms that lead to a robust variational optical flow model. Unlike the literature which most often only experimentally shows that a des...
Conference Paper
This paper introduces a robust image mosaicing method. A variational optical flow (OF) method is first proposed to deal with scenes exhibiting strong specular reflections and few texture information. Then, a general form of descriptors invariant to complex illumination variations is given from which a novel descriptor is obtained. Non-linear transf...
Article
Les endoscopes ont un rôle essentiel pour l’inspection des organes creux et des cavités du corps. Ils fournissent des images à haute résolution avec des couleurs et textures naturelles requises pour un diagnostic, le suivi des patients et les interventions chirurgicales. Cependant, leur champ de vue réduit est un facteur limitant majeur pour une in...
Conference Paper
This contribution deals with the optical flow computation in weakly textured scenes affected by strong illumination changes. The data-term is based on a new illumination invariant patch-based descriptor which also preserves the texture information. An illumination change model was used to theoretically prove that the descriptor is invariant to comp...
Conference Paper
This paper introduces a generalized descriptor formulation facilitating the design of illumination invariant data-terms in variational optical flow. This contribution also proposes a criterion to check whether a patch-based descriptor is illumination invariant or not. To do so, a local model is used to simulate complex illumination changes between...
Conference Paper
This contribution presents a fast global adjustment scheme exploiting SURF descriptor locations for constructing large skin mosaics. Precision in pairwise image registration is well-preserved while significantly reducing the global mosaicing error.
Article
Full-text available
The torsion distribution of cell paths in two-phase flow of a cell suspension through a porous medium is an important quantity for chromatographic processes. It can be estimated from cell tracking in sequences of three-dimensional images of a suspension pumped through the medium, where the images are acquired by in-situ time-resolved microtomograph...
Article
3D extended field of views (FOVs) of the internal bladder wall facilitate lesion diagnosis, patient follow-up and treatment traceability. In this paper, we propose a 3D image mosaicing algorithm guided by 2D cystoscopic video-image registration for obtaining textured FOV mosaics. In this feasibility study, the registration makes use of data from a...
Article
Full-text available
This paper presents a new approach to estimate optical properties (absorption and scattering coefficients ma and ms) of biological tissues from spatially-resolved spectroscopy measurements. A Particle Swarm Optimization (PSO)-based algorithm was implemented and firstly modified to deal with spatial and spectral resolutions of the data, and to solve...
Article
Full-text available
Curvature and torsion of three-dimensional curves are important quantities in fields like material science or biomedical engineering. Torsion has an exact definition in the continuous domain. However, in the discrete case most of the existing torsion evaluation methods lead to inaccurate values, especially for low resolution data. In this contribut...
Article
Full-text available
Abstract Total variational (TV) methods using l1-norm are efficient approaches for optical flow determination. This contribution presents a multi-resolution TV-l1 approach using a data-term based on neighborhood descriptors and a weighted non-local regularizer. The proposed algorithm is robust to illumination changes. The benchmarking of the propos...
Article
Image mosaicing is a technique widely used for extending the field of view of industrial, medical, outdoor or indoor scenes. However, image registration can be very challenging ,e.g. due to large texture variability, illumination changes, image blur and camera perspective changes. In this paper, a total variational optical flow approach is investig...
Conference Paper
Skin image mosaicing is an important task, but only few work has been published in this domain. Large field of view mosaics of cutaneous surfaces facilitate diagnosis and is unavoidable in the context of tele-medicine. This explatory (and feasibility) study compares the performances of three optical flow methods (a local method, a global graph-cut...
Conference Paper
Full-text available
Mosaicing of biological tissue surfaces is challenging due to the weak image textures. This contribution presents a mosaicing algorithm based on a robust and accurate variational optical flow scheme. A Riesz pyramid based multi-scale approach aims at overcoming the “flattening-out” problem at coarser levels. Moreover, the structure information pres...
Conference Paper
Full-text available
Cystoscopy is the standard procedure for clinical diagnosis of bladder cancer. Bladder carcinoma in situ are often multifocal and spread over large areas. In vivo, localization and follow-up of these tumors and their nearby sites is necessary. But, due to the small field of view (FOV) of the cystoscopic video images, urologists cannot easily interp...
Data
Full-text available
Published in Proc. SPIE 9129, Biophotonics: Photonic Solutions for Better Health Care IV, April 2014
Conference Paper
Full-text available
Robustness and accuracy of the existing optical flow (OF) algorithms can still be improved for noisy, low textured and poorly contrasted images. Most methods are based on the variational approach given by the Horn-Schunck model which can suffer from over-smoothing problems. In this paper, we propose to take into account the significant structural i...
Conference Paper
Full-text available
For the estimation of in vivo tissue optical parameters based on spatially-resolved diffuse reflectance spectroscopy measures, a non-derivative Particle S warm Optimisation approach was successfully applied as part of the inverse problem solving associated to forward Monte Carlo simulations to avoid trapping in local minima. Keywords—spectroscopy,...
Conference Paper
Full-text available
Determining the optical properties of biological tissues in vivo from spectral intensity measurements performed at their surface is still a challenge. Based on spectroscopic data acquired, the aim is to solve an inverse problem, where the optical parameter values of a forward model are to be estimated through optimization procedure of some cost fun...
Article
Full-text available
A mathematical simulation method was developed for visualization of the diffuse reflected light on a surface of 3-layered models of urinary bladder wall. Five states, from normal to precancerous, of the urinary bladder epithelium were simulated. With the use of solutions of classical electrodynamics equations, scattering coefficients μ s and asy...
Article
Abstract Structured-light systems (SLSs) are widely used in active stereo vision to perform 3D modelling of a surface of interest. We propose a flexible method to calibrate SLSs projecting point patterns. The method is flexible in two respects. First, the calibration is independent of the number of points and their spatial distribution inside the p...
Conference Paper
Full-text available
In white light cystoscopy, bladder images are characterized by a strong texture and scene illumination variability which complicates image mosaicing. State-of-art methods exhibit high image registration accuracy at the expense of computational time.We propose an algorithm which selects either a feature based method or an optical flow method accordi...
Conference Paper
Full-text available
Image mosaicing helps in diagnosis and follow-up of lesions in cystoscopic bladder image sequences by increasing the field of view. Optical flow methods have been used for various scenes, whereas they were barely experimented for data with poor texture and blurry images like that of endoscopic data. In this paper, we present the use of total variat...
Article
Large field-of-view panoramic images greatly facilitate bladder cancer diagnosis and follow-up. Such 2D mosaics can be obtained by registering the images of a video-sequence acquired during cystoscopic examinations. The scientific challenge in the registration process lies in the strong inter- and intra-patient texture variability of the images, fr...
Article
In mammography, image quality assessment has to be directly related to breast cancer indicator (e.g. microcalcifications) detectability. Recently, we proposed an X-ray source/digital detector (XRS/DD) model leading to such an assessment. This model simulates very realistic contrast-detail phantom (CDMAM) images leading to gold disc (representing mi...
Conference Paper
During the image placement onto the compositing surface (mosaic), stitching algorithms try to minimize visual inconsistencies (texture discontinuities), seam induced color gradients, and blurry image regions. These problems are classically processed separately. In this contribution, we describe a two step graph-cut algorithm that combines these iss...