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[Publications] [Colour Reproduction]

A 'one channel' Spectral Colour Prediction Model for Transparent Fluorescent Inks on a Transparent Support

P. Emmel, R.D. Hersch

Proc. IS&T/SID Color Imaging Conference: Color Science, Systems and Applications, 1997, pp. 70-77

Classical colour prediction models do not take fluorescence into account, and their predictions fail if fluorescent substances are contained in the inks. This is due to the fact that the overall spectrum of fluorescent substances depends on the spectrum of the light source. Furthermore, fluorescence is a non linear phenomenon. This study aims at predicting the spectra and the colours of uniform samples produced with one fluorescent ink at different concentrations. The method is based on a "one channel" modelization of the phenomenon where only one direction of propagation is taken into account. This model is used to compute the transmittance spectra of uniform colour samples. The proposed prediction model requires measuring the transmittance spectra, the quantum yields, the absorption bands and the emission spectra of the fluorescent inks. In contrast to existing fluorescence prediction methods, our approach enables, without additional measurements, to predict spectra for different ink concentrations and different light sources. Moreover, the mathematical formalism we have developed can be seen as a generalization of Beer's absorption law. We hereby obtain accurate spectral predictions of colour patches. In order to limit the number of physical parameters required, the study is carried out with transparent inks on a transparent substrate, thus avoiding all problems related to light diffusion.

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