| Jul. 2002: | GRASP Lab, Unversity of Pennsylvania, USA |
| Dec. 2001: | Computer Vision and Image Processing Group, The Chinese University of HongKong, China |
| Dec. 2001: | Image Processing group, HongKong University of Science and Technology, China |
| Apr. 2001: | Cognitive Systems Group, University of Hamburg, Germany |
| Nov. 2000: | Image Understanding and Knowledge-based Systems group, TU München, Germany |
| Nov. 2000: | Pattern Recognition and Image Processing group, University of Freiburg, Germany |
| Nov. 2000: | Interdisciplinary
Colloquium on Digital Image Processing University of Heidelberg /University of Mannheim, Germany |
| Jul. 1999: | LME group , Universität Erlangen-Nürnberg, Germany |
| Dec. 1998: | LME group , Universität Erlangen-Nürnberg, Germany |
| Dec. 1997: | IWR Image Processing group, Universität Heidelberg, Germany |