Patent ID: 7466417

Claim:
Process for the colour measurement of samples printed on substrates with brighteners, whereby a spectral reflection factor of a sample is determined and made available for the calculation of values characterizing the colour, characterized in that the spectral reflection factor of the sample is determined by way of a double measurement, whereby in a first measurement a raw spectral reflection factor of the sample is measured by illumination of the sample with light without UV portion, a fluorescence spectrum of the sample is measured in a second measurement by illumination of the sample with only UV light, the measured fluorescence spectrum is recalculated as a corrected fluorescence spectrum by way of a correction model in which the fluorescence spectrum is spectrally weighted with a set of spectrally dependent correction factors, and whereby the measured raw spectral reflection factor and the corrected fluorescence spectrum are added to form a corrected spectral reflection factor which corrected spectral reflection factor is used for the calculation of the values characterizing the colour of the sample.