A proposal for a method to measure the colour of red wines by measuring transmittance at three wavelengths

Characteristic vectors analysis has been used to reconstitute the transmittance spectrum of red wines measured in 0.2 cm path-length cells. We have verified that an accurate reconstitution of the spectrum is obtained with the mean vector and the first three characteristic vectors. Applying the outputs obtained to the colour calculation, tristimulus values are obtained as a function of transmittance measured at 420, 520 and 620 nm. The errors involved, measured in colour differences, are less than 3 CIELAB units in 97% of the cases.