Today, conventional proofing systems are more and more replaced by flexible and cheaper systems based on ink jet technology. The advantages of conventional proofing devices such as color stability, inks that mimic accurately the printing process to be simulated and a relatively high printer resolution to reproduce screened images are more and more taken over by digital ink jet systems. Moreover, due to the combination of ink jet systems and digital workflows, a printing system can be designed containing a plethora of functionalities fulfilling the needs of proofing solutions for several printing applications. Proofing is one of the most demanding printing applications in the field as the ultimate proof should be an exact copy of the print. The proof is expected to correspond closely to the look and feel of the print. The control over the color reproduction behavior of a printing system is in reality one of the key elements for the design of a proper proofing system. In general, it is not sufficient to optimize the printing device and the digital workflow; the whole system has to be optimized and integrated properly. As a minimal requirement, the color management, the calibration, the screening and the inks of the proofing device have to be tuned properly. However, it is as essential to take into account the characteristics of the printing process to be simulated and the viewing environment of the visual print-proof comparison. Too often there is a difference between a visual match and a match based on measurements.