On October 15, 2025, Julian Klabes successfully defended his dissertation entitled “On the Preferred Color Rendition of White Light Sources under Varying Adaptation Conditions” at the TU Darmstadt’s Clock Tower Auditorium and completed his doctoral examination with the grade summa cum laude (with highest distinction).

In his research, Julian Klabes investigated how the color rendition of white light sources influences visual preference depending on adaptation conditions such as illuminance and correlated color temperature. Based on a comprehensive meta-analysis and two large-scale psychophysical experiments conducted in Germany and China, he developed a model capable of predicting preferred color rendition (color preference) under varying lighting conditions. The results provide a scientific foundation for future intelligent multi-channel lighting systems and are particularly relevant for applications requiring preferred color appearance—such as in retail—or in environments where the state of visual adaptation strongly affects color perception, such as museums where illumination levels must be kept low for conservation reasons.

The examination committee was chaired by Prof. J. Frosch. The referees were Prof. T. Q. Khanh and Prof. E. Dörsam, and the examiner was Prof. S. Preu.

The Laboratory warmly congratulates Dr.-Ing. Julian Klabes on successfully completing his doctoral defense with highest distinction.