Search results for "Multispectral image"

Surface Emissivity Retrieval From Airborne Hyperspectral Scanner Data: Insights on Atmospheric Correction and Noise Removal

2012

Airborne multispectral imagers have been used in validation campaigns in order to acquire very high spatial resolution data as a benchmark for current or future satellite data. Imagery acquired with such sensors implies specific data processing in relation to view-angle-dependent atmospheric correction and removal or minimization of stripping-based noise. It is necessary to appropriately perform this processing in order to benefit from reference imageries of surface temperature (T) and emissivity (e) maps retrieved from thermal infrared data. In particular, e images generated from T/e separation algorithms show undesirable noise that jeopardizes their photointerpretation. This letter addres…

Affine compensation of illumination in hyperspectral remote sensing images

2009

A problem when working with optical satellite or airborne images is the need to compensate for changes in the illumination conditions at the time of acquisition. This is particularly critical when working with time series of data. Atmospheric correction strategies based on radiative transfer codes may provide a rigorous solution but it may not be the best solution for situations where a huge amount of hyperspectral images may need to be processed and computational time is a critical factor. The GMES (”Global Monitoring for Environment and Security”) initiative has promoted the creation of a new generation of satellites (the SENTINEL series) with ”ultra-high resolution” and ”superspectral im…

Influence of solar and sensor angles on chlorophyll estimation for geostationary ocean color imager

2012

The impact of the solar and sensor angles on band-ratio chlorophyll concentration (Chl) estimation in Case 1 waters (open ocean) is analyzed in this work. The error range of Chl estimation due to angular variation is evaluated. The radiative transfer code Hydrolight is used for remote sensing reflectance simulation for 20 spectral bands. OC4v4 algorithm is used for Chl estimation. The results indicate that the error range of Chl estimation is between -41.91% and +46.15% when Chl range is from 0.0425 mg/m 3 to 10.6685 mg/m 3 and the solar and sensor zenith angles vary between 0 and 80°. This study provides a reference to determine the effective observation area of a future multispectral or h…

RADIOMETRIC CALIBRATION OF A MULTISPECTRAL CAMERA

2006

We describe in detail a method for calibrating a multispectral imaging system based on interference filters. The calibration aims to remove systematic noises introduced by the sensor, and optic and/or filters from multispectral images. After which, we can correct the non-linearity of the sensor response. Systematic noises are measured through a rigorous protocol for acquiring offset, and thermal, and Flat-Field images. The methods for acquiring Flat-Field image, and linearizing sensor response are novel and particularly efficient in the case of a multispectral imaging system. Indeed, in such a system, the reconstruction of a spectrum for each pixel comes from the set of values taken by this…

Improvement of two-dimensional structured illumination microscopy with an incoherent illumination pattern of tunable frequency.

2018

In two-dimensional structured illumination microscopy (2D-SIM), high-resolution images with optimal optical sectioning (OS) cannot be obtained simultaneously. This tradeoff can be overcome by using a tunable-frequency 2D-SIM system and a proper reconstruction method. The goal of this work is twofold. First, we present a computational approach to reconstruct optical-sectioned images with super-resolution enhancement (OS-SR) by using a tunable SIM system. Second, we propose an incoherent tunable-frequency 2D-SIM system based on a Fresnel biprism implementation. Integration of the proposed computational method with this tunable structured illumination (SI) system results in a new 2D-SIM system…

Optimization of a polarization imaging system for 3D measurements of transparent objects

2009

This paper presents a multispectral imaging system for 3D reconstruction of transparent objects based on "shape from polarization" technique. The originality of this work relies on a multispectral active lighting system which enables to cope with the two ambiguities on the zenith angle and azimuth angle. A calibration step allows optimising the polarimetric measurements. Example of a reconstructed transparent object is presented.

Multispectral fluorescence sensitivity to acidic and polyphenolic changes in Chardonnay wines – The case study of malolactic fermentation

2022

International audience; In this study, stationary and time-resolvedfluorescence signatures, were statistically and chemometrically analyzed among three typologies of Chardonnay wines (A, B and C) with the objectives to evaluate their sensitivity to acidic and polyphenolic changes. For that purpose, a dataset was built using Excitation Emission Matrices of fluorescence (N = 103) decomposed by a Parallel Factor Analysis (PARAFAC), andfluorescence decays (N = 22), mathematically fitted, using the conventional exponential modeling and the phasor plot representation. Wine PARAFAC component C4 coupledwith its phasor plot g and s values enable the description of malolactic fermentation (MLF) occur…

2020

This work introduces a method to estimate reflectance, shading, and specularity from a single image. Reflectance, shading, and specularity are intrinsic images derived from the dichromatic model. Estimation of these intrinsic images has many applications in computer vision such as shape recovery, specularity removal, segmentation, or classification. The proposed method allows for recovering the dichromatic model parameters thanks to two independent quadratic programming steps. Compared to the state of the art in this domain, our approach has the advantage to address a complex inverse problem into two parallelizable optimization steps that are easy to solve and do not require learning. The p…

Multispectral imaging of pigmented and vascular cutaneous malformations: the influence of laser treatment

2010

The paper investigates influence and efficacy of laser therapy on pigmented and vascular cutaneous malformations by multispectral imaging technique. Parameter mapping of skin pigmented and vascular lesions and monitoring of the laser therapy efficacy are performed by multispectral imaging in wavelength range 450-700nm by scanning step - 10nm. Parameter maps of the oxyhemoglobin deoxyhemoglobin and melanin derived from the images are presented. Possibility of laser therapy efficacy monitoring by comparison of the parameter maps before and after laser treatment has been demonstrated. As both cutaneous pigmented and vascular malformations are commonly found lesions, the parameter mapping would…

Benign — A typical nevi discrimination using diffuse reflectance and fluorescence multispectral imaging system

2015

Early diagnostics of skin cancer is of interest for dermatologists. Atypical nevi are not considered to be malignant, but are suspects that should be detected and monitored over time. The multispectral imaging system Nuance operating in spectral range 450–950 nm was adapted for clinical in vivo measurements in diffuse reflectance and fluorescence mode. Mean and standard deviation values of optical density and fluorescence intensity were extracted from segmented pigmented lesions (21 benign and 26 atypical nevi) and used for further analysis. It was possible to achieve 62% sensitivity and 67% specificity for discrimination between atypical and benign lesions using averaged fluorescence mean …