In the development of lithographic presses a popular aim is to increase the degree of automation. At the same time, paper waste has to be re-duced while keeping the print quality high. These aims could be achieved by monitoring and controlling the applied ink layer thickness. It is a critical task to measure ink layer thicknesses of about 1 µm and the measurement setups are usually very complex. Therefore, ink density is a common quantity for controlling the layer thickness of semi-transparent CMYK inks. Typical measurement devices are densitometers that measure the CMYK ink absorption utilizing standardized narrow band filters. Usually, ink density is measured offline, i.e. outside the press. The ink layer thickness is directly controlled by the results of those measurements. Unfortunately, it is very difficult to implement an automatic control system of the press using offline measurements. For this an inline measurement is advantageous, where ink density is measured inside the press for every printed sheet. To implement an automatic control of ink density, inline densitometers are used. Such devices are cost intensive and complex and therefore score a poor market share for sheet fed presses. This thesis lays the foundation for a new and cost effective method for inline measurement. For that the measurement of the ink density is integrated into a print inspection system. Print inspection systems are usually camera based. They capture and compare images of each printed sheet in order to detect defects. This thesis introduces a method to derive a device specific ink density from the RGB-data without modifying the setup of the inspection system. In addition a solution is developed, that transforms this device specific ink density into a norm equivalent value. Generally, when measuring inline, the ink has not dried, yet. During the drying process, the value of the ink density develops. Neither the influencing effects of the drying process nor the magnitude of those effects to the development have been investigated, yet. Especially the short term development (less than one second) needs to be considered for an automatic control system. Therefore, a test rig was developed for measuring the ink density during drying. In this test rig, the ink is printed by standard conditions of the lithographic printing process. From the results of the experiments, an empirical model could be derived. This model describes the development of the ink density during drying. Influencing effects could be separated by their time constants. Furthermore, the development of the ink density varies with substrates and inks. This correlation can also be shown by the model.