Process and apparatus for controlling the inking process in a printing machine

摘要

To improve the control of the inking process in an offset printing machine, color measuring fields provided on printed sheets are evaluated not as heretofore densitometrically but colorimetrically by means of spectral measurements. Spectral reflections are used to match colors, or color coordinates are calculated from them and compared with corresponding set reflections or set color coordinates. The color deviations obtained in this manner are used to control the inking process. For the stabilization of printing runs the spectral reflections are converted into filter color densities and the inking process is controlled on the basis of these color densities in a conventional manner. The control of the inking process using color deviations and control using color density may be superposed upon each other. The process makes it possible to adapt color impressions in delicate locations of importance for the image in the print to the corresponding locations of the proof. Color deviations due to different material properties and other error sources may also be equalized to some extent.