Correspondence:
[**]
Address for correspondence: Prof. em. Franz Fankhauser, MD, Postfach 622, CH 3000 Bern 8, Switzerland. E-mail: [email protected].
Note: [*] Hans Giger, PhD (1921–2004) was a universal spirit. He received his PhD from the Mathematics Department of the University of Bern. He then worked as a teacher of physics and mathematics at a junior college in Bern, but took a leave of absence from his position from 1966 to 1968 to work with Professor Goldmann, head of the University Eye Clinic and with Dr. Fankhauser on a number of basic projects related to their work. Due to his universality, he was able to help in the solution of major problems associated with glaucoma and basic mechanisms of vision. During these years, he also worked for the Mineralogy Department of the University of Heidelberg (Germany) and received the degree as a lecturer. At about the same time, he was awarded the Haller medal of the University of Bern. He retired in 1992 and enjoyed painting in the Swiss mountains. Hans Giger was a great scientist and a great friend.
Abstract: An analysis and mathematical comparison of models underlying the phenomena of brightness and contrast are presented. The concept of self-excitation which has not so far been considered is introduced into the structure of the models. Mach Bands can be described by two essentially different but formally identical mechanisms. The phenomenon allows neither a functional explanation in terms of models presented heretofore nor an answer to the question whether data processing is based in the human visual system on integrating of differentiating of on both.
