REAL-TIME EXPLORATION OF VOLUMETRIC DATA is an important toolthat allows finding details hidden within the data that would usually be overlooked, thus providing additional insight compared with static visualizations. Hence, one of the most important goals of volume rendering is to generate results under a given time constraint to provide a high frame rate and thus interactivity to the user. Time constraints, however, quite often require trade-offs between quality and performance, which can be made at different stages of the volume-rendering pipeline. Depending on the trade-offs made, more or less apparent artifacts are visible in the resulting images. In this chapter, we will therefore first identify possible sources of artifacts during the volume-rendering process. After this improved understanding of the sources of artifacts, we can then find methods to produce high-quality volume visualizations even under given time constraints.