Gereon Fox. Photo: Bertram Somieski/MPI-INF
On August 26, Gereon Fox successfully defended his thesis with the title "Learning and exploiting temporal dependencies in the synthesis and analysis of video signals". He joined MPI for Informatics as a doctoral researcher in April 2019. The thesis was supevised by Prof. Dr. Christian Theobalt, Scientific Director of the Visual Computing and Artifcial Intelligence department. The doctoral degree is awarded by Saarland University.
Abstract of the thesis:
The acquisition, reproduction, analysis and modification of visual information are important in all parts of human life – even more so since the advent of sufficiently capable computers. Especially the computational treatment of the temporal dimension is challenging, but also beneficial for many applications. This thesis explores the temporal dimension in three different contexts:
For the detection of semantically relevant manipulations, it demonstrates that previous detection methods can be fooled by the same improvements to the manipulation technique that would fool human observers. New methods are presented to nevertheless achieve high detection accuracy, and especially temporal dependencies are shown to help generalise to unseen manipulation methods.
For the synthesis of new video signals, previous work has constructed models that entangle spatial and temporal features. This thesis separates these features, reducing memory demand and computation time, as well as the amount of data necessary for training.
For the reconstruction of video signals from event data, a data modality for which training data is scarce, the thesis presents a method to turn event data into watchable signals, without using any training data at all, but outperforming previous methods that do so.
In each of these contexts, the thesis highlights the degree to which solutions depend on training sets of different sizes, and the impact this has on performance and computational cost.