In Memoriam: TilAach, 1961-2012

By Scott T. Acton and Rudolf Mester

It was with great regret and sadness that the Signal & Image Processing community learned about the sudden loss of TilAach, beginning of this year. Our community will miss a great mind who contributed to both theory and applications, and those who knew him have lost a dear friend. As a tribute to Til and the legacy he leaves for our research field, we welcome personal contributions from two of his colleagues  and friends:

Scott Acton: I first met TilAach in the nineties in Japan. We bonded quickly over image processing and beer. It was a friendship that would last until his untimely death. I value Til as a gifted colleague… and as if he were a brother.

Til was an adventurer. He spoke a handful of languages fluently, including ancient Greek, which he attempted on a confused Saloniki waiter.  He was a hearty traveler undaunted by the inevitable hiccups. I remember an extremely turbulent flight that we shared in a small plane over the Rocky Mountains. In my panic, I looked over at Til – he was calm, reading a Transactions article and eating airport Sushi!

He was a devoted family man.  After ISBI 2010, I was trapped on the Continent due to the unpronounceable volcano Eyjafjallajökull.  The Aach family adopted me for a week.  There, in Aachen (yes, TilAach lived in his namesake Aachen!), I was able to get to know his family: his wife Elisabeth, his son Marcel and his daughter Linda.There we ate large German breakfasts, cycled, and enjoyed the extravagant flora planted on the grounds by Til’s botanist father. It is at homewhereTil will be missed beyond what we can imagine as colleagues.

He was a prolific researcher and a gem to the image processing community. Til was always excited about his latest theory, was always ready to demonstrate his latest application (we both have an affinity for the biological/biomedical) and was always training, mentoring and promoting a host of capable students.

Rudolf Mester: I met TilAach while I was still a Ph.D. student at RWTH Aachen; he came into our institute and asked various scientists there for a task and problem to be addressed in his Dipl.-Ing. Thesis (what is a Masters degree in the U.S.). Well, it was not very hard to see that this was an exceptionally bright and ambitious student, and I had to work hard against considerable competitionfor finally getting him to choose a subject related to my own work, which finally led to his Diplomthesis ‘Investigations in texture oriented image segmentation’ in 1987. This work addressed the problem of defining quadrature filter banks which yield texture feature vectors with particular characteristics. They reflect differences in texture in a way which is accessible to a multi-channel statistical model. Til really excelled with his thesis which was to become also the core of a conference paper and journal article, and in conjunction with his superb grades obtained as a student in Electrical Engineering, he received the Springorum Medal of RWTH Aachen. No wonder that he obtained a research associate position at the same institute, once more with significant competition from other institutions.

TilAach, UweFranke and I had a very productive period of working closely together from about 1987 to 1989, sharing one office and many ideas, and trying to promote image analysis, Bayesian methods, and object-oriented models into the (at that time) more conservative world of image representation and coding. When UweFranke and me left RWTH Aachen after having obtained our Dr.-Ing. Degrees in 1989, André Kaup had shortly before joined the team – he was to become another one of the long-term co-workers and close friend to TilAach. While I was in industry, and later while being with U. Frankfurt, I continued to cooperate with Til on motion detection and segmentation, and this lead to several papers and a patent.

If you find a friend and colleague of the format that Til had, you better stay in touch with him. We met often at international conferences, and making an appointment for the post-conferences evenings with him and the numerous friends he had from his even more numerous trips to all imaginable locations was a guarantee for a funny and enjoyable evening. I knew Til as an always good-humored person, always friendly and respectful towards others. His well-tempered attitude to everybody did not restrain him from always being exceptionally diligent in all professional matters. What ever he did in his profession, he did it carefully, thoughtfully, and properly.

At the time of his death, TilAach was head of the Institute of Imaging and Computer Vision at RWTH Aachen University in Aachen, Germany. Previously, he served asdirector of the Institute for Signal Processing at the University of Lübeck, Germany and was with Philips Research Laboratory.  During his career, Prof. Aach published three books, three book chapters, 49 journal papers, 250 conference papers, 22 patents and many other works investigating several aspects of medical and industrial image processing, signal processing, pattern recognition and computer vision. He, with André Kaup and Rudolf Mester, introduced a widely cited Markov random field model for change detection in“Statistical model-based change detection in moving video,” (Signal Processing, vol. 31, no. 2, pp. 165-180).

Prof. Aach was senior member of IEEE, member of the Bio-Imaging and Signal Processing Technical Committee (BISP-TC), member of the IEEE Signal Processing Society, member of the International Society for Optical Engineering (SPIE), Associate Editor of the IEEE Transaction on Image Processing, Technical Program Co-Chair for the IEEE Southwest Symposium on Image Analysis and Interpretation (SSIAI) in 2000, 2002, 2004, and 2006. He was member of the Verband der ElektrotechnikElektronikInformationstechnike.V. (VDE): InformationstechnischeGesellschaft (ITG), Deutsche GesellschaftfürBiomedizinischeTechnik (DGBMT).

Prof. Aach is survived by his wife Elisabeth, his son Marcel and his daughter, Linda.