Search results for "Correlation"
showing 10 items of 2282 documents
An evaluation framework and a benchmark for multi/hyperspectral image compression
2011
International audience; This paper benchmarks three multi/hyperspectral image compression approaches: the classic Multi-2D compression approach and two different implementations of 3D approach (Full 3D and Hybrid). All approaches are combined with a spectral PCA decorrelation stage to optimize performance. These three compression approaches are compared within a larger comparison framework than the conventionally used PSNR, which includes eight metrics divided into three families. The comparison is carried out with regard to variations in bitrates, spatial, and spectral dimensions variations of images. The time and memory consumption difference between the three approaches is also discussed…
Parameter-free adaptive step-size multiobjective optimization applied to remote photoplethysmography
2018
International audience; In this work, we propose to reformulate the objective function of Independent Component Analysis (ICA) to make it a better posed problem in the context of Remote photoplethysmography (rPPG). In recent previous works, linear combination coefficients of RGB channels are estimated maximizing the non-Gaussianity of ICA output components. However, in the context of rPPG a priori knowledge of the pulse signal can be incorporated into the component extraction algorithm. To this end, the contrast function of regular ICA is extended with a measure of periodicity formulated using autocorrelation. This novel semi-blind source extraction method for measuring rPPG has the interes…
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…
Recent changes in measured wind in the NE Atlantic and variability of correlation with NAO
2010
The paper deals with wind measurements, recorded since the 1950s, at twelve meteorological stations along a transect near the westernmost European border, between 64° and 44° N. Extreme wind speed tends to decrease sharply near the northern boundary (at Reykjavick), near the middle of the study area (at Shannon and Valentia) and near the southern boundary (at Brest and Cap Ferret), to increase at Thorshavn, with less significant trends at the other stations. Average wind speeds confirm the above tendencies, with an additional increasing speed at Lerwick, Kirkwall, Malin Head, Belle-Ile and Cap Ferret. To compare changes in wind activity, the data have been subdivided into three periods: unt…
Advanced 3D movement analysis algorithms for robust functional capacity assessment.
2017
SummaryObjectives: We developed a novel system for in home functional capacities assessment in frail older adults by analyzing the Timed Up and Go movements. This system aims to follow the older people evolution, potentially allowing a forward detection of motor decompensation in order to trigger the implementation of rehabilitation. However, the pre-experimentations conducted on the ground, in different environments, revealed some problems which were related to KinectTM operation. Hence, the aim of this actual study is to develop methods to resolve these problems.Methods: Using the KinectTM sensor, we analyze the Timed Up and Go test movements by measuring nine spatio-temporal parameters, …
All-Optical Measurement of Background, Amplitude and Timing Jitter for high speed pulse trains or prbs sequences using autocorrelation function
2006
We present a simple method for all-optical measurements of background, amplitude- and timing-jitter of ultra high speed pulse trains or prbs sequences using the jitter dependences of the intercorrelation-peak shape.
Statistical analysis of pulse propagation driven by polarization-mode dispersion
2002
International audience; The linear propagation of pulses driven by random polarization-mode dispersion is considered. Analytical expressions are derived for the probability-density functions of the pulse width, timing displacement, and degree of polarization. The study is performed in Stokes space, and frequency correlation between modes is shown to play an important role in it.
Modelling analysis of centroid curves of olfactory habituation in humans
2020
Indexation en cours.; International audience; Previously published experiments established the time-course of olfactory habituation in humans, and extracted 3 centroid curves from clustering analysis that reflected high, middle and low habituation. The aim of the current theoretical study was to further analyse these previous experimental data by developing a mathematical modelling analysis designed for fitting the 3 curves from a general equation. After adjusting equation parameters for each curve, fitting equation outcomes on experimental data yielded high correlation coefficients of 0.9997 – 0.9995 – 0.9962, respectively. A model-based interpretation of olfactory-habituation centroid cur…
Predicting spread patterns of centrifugal fertiliser spreaders
2014
International audience; Nowadays farmers recognize the importance of a correct and precise fertiliser application: non-uniform spread patterns cause extra pressure on the environment and might result in economic losses for the farmer. In Europe most spreading is done by centrifugal fertilizer spreaders but their spreading process is not easy to monitor and to control. To perform a precise fertilising farmers need proper tools to determine and evaluate the spread pattern at farm level. Therefore the Flemish Institute for Agricultural and Fisheries Research (ILVO) is exploring and developing a fast and accurate technique for measuring the spread pattern of conventional centrifugal spreaders. …
A simple method for estimating downward longwave radiation from surface and satellite data by clear sky
1990
Abstract An attempt to derive downward longwave radiation at the surface in clear sky conditions is presented. A method that integrates satellite-measured infrared radiation temperatures with ground measurements of water vapour pressure is applied to Meteosat data. Satellite-derived fluxes are compared with corresponding ground-measured fluxes at three different sites in France and during various seasons. Comparison of the daily averaged fluxes shows a correlation coefficient of 0–88 and an r.m.s. difference between satellite estimates and ground measurements of 12 Wm-2.