title: Low-frequency correlations (1/f(α) type) in paint application of metallic colors.
abstract: We examine trial-to-trial variability of color coordinates in automotive coatings containing effect pigments, which are considered a reference paradigm for engineering angle-dependent color effects. We report the existence of correlations that show 1/f - Fourier spectra at low frequencies in all color coordinates. The scaling exponent was lower at near-specular conditions for lightness variations, suggesting a contribution from the deposition of metal flakes in metallic colors. However, the exponent was lower near the specular for blue-yellow variations, suggesting a contribution from chemical pigments in solid colors. These results were independent of the illuminant spectra. The methods employed are useful in the evaluation of industrial color matching among assembly parts.
authors.affiliation: Center for Physics, University of Minho, Campus de Gualtar, Braga, 4710-057, Portugal. jmanuel@fisica.uminho.pt
authors.forename: José M
authors.initials: JM
authors.lastname: Medina
authors.forename: José A
authors.initials: JA
authors.lastname: Díaz