International. Spanish researchers from the University of Granada have analysed the statistical properties of colour coordinates for colour matching in automotive metal coatings. Color matching between the body and the assembled complementary parts is a complex process that increases costs and time in car manufacturing.
CIELAB coordinates (CIE 1976, light L*, A* red-green and b* blue-yellow) were calculated using multi-angle spectrometric reflectance measurements from a wide range of metal coatings from different manufacturers.
The scientists found that variations of L* – trial by trial – are related to a self-similar stochastic process. The variance of the sample and the mean sample value of L* calculated over different viewing angles are correlated between painted pieces. A power function model describes the data quite well.
This power function corresponds to a wide-diffusion phenomenon known as fluctuation scaling in many engineering processes. They also found that the sample asymmetry and sample kurtosis of L*, a*, and b* follow a U-shaped pattern and a generalized version of the fluctuation scale.
The exponent of the fluctuation scale in the skewness-kurtosis plane depends on the cardinal directions, L*, a* and b*. This suggests that different flake-shaped pigments mediate the correlations of color coordinates from one assay to another. The researchers conclude that the fluctuation scale provides a powerful approach for better prediction of lightness flop variations and for better color quality control among automakers and suppliers of additional parts.
The exponent of the fluctuation scale in the skewness-kurtosis plane depends on the cardinal directions, L*, a* and b*. This suggests that different flake-shaped pigments mediate the correlations of color coordinates from one assay to another. The researchers conclude that the fluctuation scale provides a powerful approach for better prediction of lightness rest variations and for better color quality control among automakers and suppliers of additional parts.
Source: www.sciencedirect.com
