The Use of Colorimetric Values to Setup the Printing Press

Since a few years, the family of ISO 12647 Norms have been updated specifying CIELAB color values parameters for normal process control thus obliging press operators to use spectrophotometry and densitometry in the same time. This system can present some difficulties when setting up and keeping under control production printing equipments. The object of this research, started four years ago, is that of finding out a methodology to obtain the correct ink values starting from the CIELAB references. The densitometry is always the most common way to predict the amount of ink. Anyway no mathematical relationship can be done with the CIELAB measurements because both the densitometric and colorimetric values come from different sampling of the spectrum. In this research different colorimetric coordinates belonging to the various CIE color spaces have been tested in different printing conditions with a number of inks, in order to verify which one is the more representative, useful and reliable to get the target colorimetric values with the minimum deltaE*