Abstract: In order to use realistic image synthesis successfully in research and development as well as in commercial products, two important prerequisites have to be fulfilled. First of all, good, accurate, robust, and fast algorithms are required. Impressive progress has been made in this respect during the last years, which has also been documented in this workshop. The second step is the creation of a suitable and general software architecture, that offers an environment into which these rendering algorithms can be integrated. In this paper, we develop an architecture that consists of a small,but flexible rendering kernel. This kernel provides a general framework for rendering algorithms and defines suitable interfaces for specific aspects of rendering, like reflection (BRDF) or emission. Algorithms for a certain aspect of the rendering process can then be plugged into the kernel in order to implement a particular rendering strategy. The benefits of this approach is demonstrated with several applications.