Color calibration of an RGB camera mounted in front of a microscope with strong color distortion

International audienceThis paper aims at showing that performing color calibration of an RGB camera can be achieved even in the case where the optical system before the camera introduces strong color distortion. In the present case, the optical system is a microscope containing a halogen lamp, with a nonuniform irradiance on the viewed surface. The calibration method proposed in this work is based on an existing method, but it is preceded by a three-step preprocessing of the RGB images aiming at extracting relevant color information from the strongly distorted images, taking especially into account the nonuniform irradiance map and the perturbing texture due to the surface topology of the standard color calibration charts when observed at micrometric scale. The proposed color calibration process consists first in computing the average color of the color-chart patches viewed under the microscope; then computing white balance, gamma correction, and saturation enhancement; and finally applying a third-order polynomial regression color calibration transform. Despite the nonusual conditions for color calibration, fairly good performance is achieved from a 48 patch Lambertian color chart, since an average CIE-94 color difference on the color-chart colors lower than 2.5 units is obtained

Narrow band resonant grating of 100% reflection under normal incidence

9 pagesInternational audienceA resonant grating mirror comprising a multilayer submirror and a grating slab waveguide submirror exhibiting constructive mutual reflection is shown experimentally to provide zero transmission. Its reflection line width of less than 1 nm, its polarization selectivity and low overall loss make the device usable as a longitudinal mode filter in a disk laser in the 1000-1100 nm wavelength range

Self-organized growth of metallic nanoparticles under homogeneous light excitation

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Laser induced physico-chemistry and self-organization of metallic nanoparticles in TiO2 films

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Self-organization and plasmonic hybridization of metal nanoparticle ensembles

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le laser pour créer des surfaces à apparence changeante

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Inscription multicolore reconfigurable haute résolution

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Propriétés optiques de nanoparticules métalliques en matrice diélectrique : application au filtrage optique

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Multidimensionality of plasmonic colors. Application to laser printing of multiplexed images

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Optically Induced Nanostructures. Biomedical and Technical Applications. Edited by Karsten König and Andreas Ostendorf. De Gruyter, 2015. Pp. XL+329. Price Euro 119.95, USD 168, GBP 89.99.

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