Julien Fleureau

Multivariate empirical mode decomposition and application to multichannel filtering

Empirical Mode Decomposition (EMD) is an emerging topic in signal processing research, applied in various practical fields due in particular to its data-driven filter bank properties. In this paper, a novel EMD approach called X-EMD (eXtended-EMD) is proposed, which allows for a straightforward decomposition of mono- and multivariate signals without any change in the core of the algorithm. Qualitative results illustrate the good behavior of the proposed algorithm whatever the signal dimension is. Moreover, a comparative study of X-EMD with classical mono- and multivariate methods is presented and shows its competitiveness. Besides, we show that X-EMD extends the filter bank properties enjoyed by monovariate EMD to the case of multivariate EMD. Finally, a practical application on multichannel sleep recording is presented.

Physiological-Based Affect Event Detector for Entertainment Video Applications

In this paper, we propose a methodology to build a real-time affect detector dedicated to video viewing and entertainment applications. This detector combines the acquisition of traditional physiological signals, namely, galvanic skin response, heart rate, and electromyogram, and the use of supervised classification techniques by means of Gaussian processes. It aims at detecting the emotional impact of a video clip in a new way by first identifying emotional events in the affective stream (fast increase of the subject excitation) and then by giving the associated binary valence (positive or negative) of each detected event. The study was conducted to be as close as possible to realistic conditions by especially minimizing the use of active calibrations and considering on-the-fly detection. Furthermore, the influence of each physiological modality is evaluated through three different key-scenarios (mono-user, multi-user and extended multi-user) that may be relevant for consumer applications. A complete description of the experimental protocol and processing steps is given. The performances of the detector are evaluated on manually labeled sequences, and its robustness is discussed considering the different single and multi-user contexts.

Affective Benchmarking of Movies Based on the Physiological Responses of a Real Audience

We propose here an objective study of the emotional impact of a movie on an audience. An affective benchmarking solution is introduced making use of a low-intrusive measurement of the well-known Electro Dermal Answer. A dedicated processing of this biosignal produces a time-variant and normalized affective signal related to the significant excitation variations of the audience. Besides the new methodology, the originality of this paper stems from the fact that this framework has been tested on a real audience during regular cinema shows and a film festival, for five different movies and a total of 128 audience members.

HapSeat: producing motion sensation with multiple force-feedback devices embedded in a seat

We introduce a novel way of simulating sensations of motion which does not require an expensive and cumbersome motion platform. Multiple force-feedbacks are applied to the seated users body to generate a sensation of motion experiencing passive navigation. A set of force-feedback devices such as mobile armrests or headrests are arranged around a seat so that they can apply forces to the user. We have dubbed this new approach HapSeat. A proof of concept has been designed which uses three low-cost force-feedback devices, and two control models have been implemented. Results from the first user study suggest that subjective sensations of motion are reliably generated using either model. Our results pave the way to a novel device to generate consumer motion effects based on our prototype.

Framework for enhancing video viewing experience with haptic effects of motion

This work aims at enhancing a classical video viewing experience by introducing realistic haptic feelings in a consumer environment. More precisely, a complete framework to both produce and render the motion embedded in an audiovisual content is proposed to enhance a natural movie viewing session. We especially consider the case of a first-person point of view audiovisual content and we propose a general workflow to address this problem. This latter includes a novel approach to both capture the motion and video of the scene of interest, together with a haptic rendering system for generating a sensation of motion. A complete methodology to evaluate the relevance of our framework is finally proposed and demonstrates the interest of our approach.

Turning Tangent Empirical Mode Decomposition: A Framework for Mono- and Multivariate Signals

A novel empirical mode decomposition (EMD) algorithm, called 2T-EMD, for both mono- and multivariate signals is proposed in this correspondence. It differs from the other approaches by its computational lightness and its algorithmic simplicity. The method is essentially based on a redefinition of the signal mean envelope, computed thanks to new characteristic points, which offers the possibility to decompose multivariate signals without any projection. The scope of application of the novel algorithm is specified, and a comparison of the 2T-EMD technique with classical methods is performed on various simulated mono- and multivariate signals. The monovariate behaviour of the proposed method on noisy signals is then validated by decomposing a fractional Gaussian noise and an application to real life EEG data is finally presented.

Enhancing Audiovisual Experience with Haptic Feedback: A Survey on HAV

Haptic technology has been widely employed in applications ranging from teleoperation and medical simulation to art and design, including entertainment, flight simulation, and virtual reality. Today there is a growing interest among researchers in integrating haptic feedback into audiovisual systems. A new medium emerges from this effort: haptic-audiovisual (HAV) content. This paper presents the techniques, formalisms, and key results pertinent to this medium. We first review the three main stages of the HAV workflow: the production, distribution, and rendering of haptic effects. We then highlight the pressing necessity for evaluation techniques in this context and discuss the key challenges in the field. By building on existing technologies and tackling the specific challenges of the enhancement of audiovisual experience with haptics, we believe the field presents exciting research perspectives whose financial and societal stakes are significant.

Raman Spectroscopy: A Novel Experimental Approach to Evaluating Renal Tumours

BACKGROUND New optical techniques of spectroscopy have shown promising results in the evaluation of solid tumours. OBJECTIVE To evaluate the potential of Raman spectroscopy (RS) to assess renal tumours at surgery. DESIGN, SETTING, AND PARTICIPANTS Over a 5-mo period, Raman optical spectra were prospectively acquired on surgical renal specimens removed due to suspicion of cancer. MEASUREMENTS Raman measures were normalised to ensure comparison between spectra. A lower resolution signal was computed using a wavelet decomposition procedure to diminish the size of the signal and exploit the complete spectrum. A support vector machine (SVM) with a linear kernel and a sequential minimal optimisation solver was applied. A leave-one-out cross-validation technique was used to train and test the SVM. RESULTS AND LIMITATIONS There were 36 patients with 34 malignant tumours (27 clear-cell, 6 papillary, and 1 chromophobe) and 2 benign (1 oncocytoma and 1 metanephric cyst) tumours. A total of 241 analysable Raman spectra were obtained. The SVM was able to classify tumoural and normal tissue with an accuracy of 84% (sensitivity 82%, specificity 87%). High-grade and low-grade tumours were differentiated with a precision of 82% (sensitivity 84%, specificity 80%). Histologic subtype could be categorised with an accuracy of 93% (sensitivity 96%, specificity 87%). SVM could not be applied to classify benign and malignant tumours because of the restricted number of benign spectra. CONCLUSIONS RS can accurately differentiate normal and tumoural renal tissue, low-grade and high-grade renal tumours, and histologic subtype of renal cell carcinoma. Larger prospective studies are needed to confirm these preliminary data.

Assessment of global cardiac function in MSCT imaging using fuzzy connectedness segmentation

The goal of this work is to assess global cardiac function in terms of ventricular volume from multi-slice computed tomography dynamic dataset. We propose an approach for the segmentation of the left ventricle and the measurement of the ventricular volume along the whole cardiac cycle. It is based on the segmentation of the left cavities using a fuzzy connectedness algorithm. The interactive placement of a 3D valvular plane is then used to cut through the segmented surface in order to extract the left ventricle. This method provides, with few interactions, the cardiac volume along the whole cardiac cycle and global parameters such as end-cardiac phases volumes and ejection fraction. Results have been compared to measures estimated during clinical routine with MSCT and MRI and have provided satisfying results. The specificity and the sensibility of the method have also been measured by a comparison with a manual segmentation of reference, leading to a very good specificity of the proposed approach.

3D Multi-Object Segmentation of Cardiac MSCT Imaging by using a Multi-Agent Approach

We propose a new technique for general purpose, semi-interactive and multi-object segmentation in N- dimensional images, applied to the extraction of cardiac structures in multislice computed tomography (MSCT) imaging. The proposed approach makes use of a multi-agent scheme combined with a supervised classification methodology allowing the introduction of a priori information and presenting fast computing times. The multi-agent system is organised around a communicating agent which manages a population of situated agents which segment the image through cooperative and competitive interactions. The proposed technique has been tested on several patient data sets. Some typical results are finally presented and discussed.