On August 31 2021 at 16.00 Ayyoub Ahar will defend his PhD entitled “Visual Quality Assessment And Analysis For Digitial Holography”. A link to the online defence will be made available later.
Since its invention in 1948, holography has held the promise to empower full-parallax 3D visualization. To facilitate an immersive 3D experience, dynamic holography is required such that it can continuously provide wide field of view and full-parallax with high spatial-resolution rendering. Though, only in recent years it has returned to the forefront of 3D visualization technologies. Presence of multiple signal processing challenges beside several hardware bottlenecks, prevented this technology to be effectively utilized for visualization purposes, especially for 3D scenes of macroscopic-scale and beyond.
One of the core remaining challenges is quality assessment of holograms and perceptual quality analysis of their reconstructions. Despite its vital role in steering other components of the holographic processing pipeline, visual quality assessment of holograms has struggled to reach its primary milestones. On this topic, some of the main contributing issues include presence of speckle noise, lack of comprehensive— perceptually annotated—holographic datasets, complexities regarding fidelity measurements of complex-valued data and perceptual quality prediction of the rendered 3D scene from the heavily noisy fringe patterns of the holographic complex wavefield. Furthermore, efficient representation of holograms via novel and customized mathematical transforms and algorithms is a hot topic due to substantial divergence between mathematical properties and statistics of the holographic content compared to the natural photographic imaging. Although, a handful of experiments have been performed to measure the effect of quantization on the reconstruction quality of holographic signals, little formal information is available on the perception of reconstruction errors by the human visual system. Moreover, knowledge from current 2D and 3D perception research can only be partially extrapolated to a holographic setting. Additionally, mature rendering devices are missing as well. These complications lead to the conclusion that parameterizing the quality perception of the digital holograms is a very exploratory process and of high risk.
From a global perspective, this research track covers necessary components in support of (1) modeling the behavior of the human visual system based upon psychovisual experiments, (2) subjective quality testing procedures and (3) performance analysis of the available quality measures on holographic content and (4) the design of related perceptual quality metrics. Along the way, several intermediary issues are also addressed to allow fulfilling the accounted objectives. Consequently, this dissertation facilitates several necessary building blocks for designing cutting-edge perceptual quality prediction algorithms and paves the way for further advances in this new topic.