The ink in a printing press, in which a stock of material is being printed in an ongoing printing process, is registered. At least one ink is applied to the stock in several inking zones. A measured value, indicating an ink density, is determined for the at least one ink which is being applied to the stock in the printing process and within the printing press. A relation is formed between the measured ink density for a specific ink in a selected ink zone and a measured ink density value determined for the same ink in at least one other inking zone. The relation between the measured ink density values in different inking zones is formed only if the majority of the inking zones of a specific inking unit of the printing press supply one respective measured ink density value for an ink supplied by that inking unit, and when the measured ink density value reaches at least a predetermined fraction of a preset, desired value in the respective inking zone.