Colorimetric and spectral evaluation of the optical anisotropy of metallic and pearlescent samples

Chorro, Elísabet; Perales, Esther; Verdú, Francisco M. Martínez; Campos, J.; Aglio, Alicia Pons

doi:10.1080/09500340903171706

Cited by 16 publications

(12 citation statements)

References 20 publications

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“…The increasing popularity of these coatings demands the development of new techniques and instruments to characterize the spectral reflectance and the color as a function of the different irradiation/viewing geometrical configurations [3,[6][7][8][9][10][11][12][13][14], and for different illuminants and real light sources [15]. Full knowledge of the spectral bidirectional reflectance distribution function (BRDF) of these coatings makes it possible to infer the coating color for any geometrical configuration (irradiation and viewing directions and solid angles) as well as the spectral distribution of the irradiation [16].…”

Section: Introductionmentioning

confidence: 99%

Spectral BRDF-based determination of proper measurement geometries to characterize color shift of special effect coatings

et al. 2013

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A reduced set of measurement geometries allows the spectral reflectance of special effect coatings to be predicted for any other geometry. A physical model based on flake-related parameters has been used to determine nonredundant measurement geometries for the complete description of the spectral bidirectional reflectance distribution function (BRDF). The analysis of experimental spectral BRDF was carried out by means of principal component analysis. From this analysis, a set of nine measurement geometries was proposed to characterize special effect coatings. It was shown that, for two different special effect coatings, these geometries provide a good prediction of their complete color shift.

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Section: Introductionmentioning

confidence: 99%

Spectral BRDF-based determination of proper measurement geometries to characterize color shift of special effect coatings

et al. 2013

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“…Panels with metallic finishes usually show a change in lightness, while those with an interference finish effect also exhibit hue and chroma changes. On account of this, to characterise this type of panel it is important to measure the colour at different measurement geometries . Nowadays, there are several colour‐measuring instruments, known as multiangle spectrophotometers or gonio‐spectrophotometers, which have been designed to measure and characterise homogeneous colours in these types of panel.…”

Section: Introductionmentioning

confidence: 99%

The minimum number of measurements for colour, sparkle, and graininess characterisation in gonio‐apparent panels

Chorro

Burgos

Gómez

et al. 2015

Coloration Technology

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Abstract:Materials with new visual appearances have emerged over the last few years. In the automotive industry in particular, there is a growing interest in materials with new effect finishes, such as metallic, pearlescent, sparkle and graininess effects. Typically for solid colors the mean of the three measurements with repetitions it is enough for obtaining a representative measurement of the color characterization. But gonio-apparent samples are colors not homogeneous and there are not studies that recommend the minimal number of repetitions for color, sparkle and graininess characterization in this type of panels. We suppose that the color panels incorporating special-effect pigments in their color recipes will require a higher minimum number of measurements than solid color panels. Therefore the purpose of this study is to confirm this by using a multiangle spectrophotometer BYK-mac, given that it is currently the only commercial device that can measure color, sparkle and graininess values simultaneously. In addition, this paper shows a possible methodology for assessing the minimum number of measurements when characterising gonio-apparent materials using a specific instrument. Thus, we studied the minimum number of measurements needed to characterize the color, sparkle and graininess of three types of samples with solid, metallic and http://mc.manuscriptcentral.com/cte Coloration Technology

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“…The increasingly popularity of these coatings demands the development of new techniques and instruments to characterize them [3,[10][11][12][13][14][15][16][17][18], that is, to determine the relation between the color variables of the coating (spectral distribution, hue, or chroma) and the different irradiation/viewing geometrical configurations. The global solution of this problem lies in the complete knowledge of the spectral bidirectional reflectance distribution function (BRDF) of these coatings, because this distribution function allows the complete spectral reflectance to be calculated, and, therefore the color for any geometrical configuration (irradiation and viewing directions and solid angles) and spectral distribution of the irradiation [19].…”

Section: Introductionmentioning

confidence: 99%

Variables separation of the spectral BRDF for better understanding color variation in special effect pigment coatings

et al. 2012

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A type of representation of the spectral bidirectional reflectance distribution function (BRDF) is proposed that distinctly separates the spectral variable (wavelength) from the geometrical variables (spherical coordinates of the irradiation and viewing directions). Principal components analysis (PCA) is used in order to decompose the spectral BRDF in decorrelated spectral components, and the weight that they have at every geometrical configuration of irradiation/viewing is established. This method was applied to the spectral BRDF measurement of a special effect pigment sample, and four principal components with relevant variance were identified. These four components are enough to reproduce the great diversity of spectral reflectances observed at different geometrical configurations. Since this representation is able to separate spectral and geometrical variables, it facilitates the interpretation of the color variation of special effect pigments coatings versus the geometrical configuration of irradiation/viewing.

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Colorimetric and spectral evaluation of the optical anisotropy of metallic and pearlescent samples

Cited by 16 publications

References 20 publications

Spectral BRDF-based determination of proper measurement geometries to characterize color shift of special effect coatings

Spectral BRDF-based determination of proper measurement geometries to characterize color shift of special effect coatings

The minimum number of measurements for colour, sparkle, and graininess characterisation in gonio‐apparent panels

Variables separation of the spectral BRDF for better understanding color variation in special effect pigment coatings

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