Invited Talks

Perspectives on Imaging with Diffractive Flat Optics

Flat optics have been applied successfully for focusing and imaging for many decades. Their recent resurgence is fueled by advances in computational electromagnetics and nanofabrication. In this brief perspective, we summarize the key connections of flat lenses to holograms, describe the current state of diffractive flat lenses, propose an effective metric to compare their performance (the generalized strehl ratio), and muse on potential areas for future research.

Rajesh Menon combines his expertise in nanofabrication, computation and optical engineering to impact myriad fields including super-resolution lithography, metamaterials, broadband diffractive optics, integrated photonics, photovoltaics and computational optics. His research has spawned over 150 publications, over 40 patents, and 4 spin-off companies. Rajesh is a Fellow of the Optical Society of America, and a Fellow of the SPIE, and a Senior Member of the IEEE. Among his other honors are a NASA Early Stage Innovations Award, NSF CAREER Award and the International Commission for Optics Prize. He currently directs the Laboratory for Optical Nanotechnologies at the University of Utah. He received S.M. and Ph.D. degrees from MIT.

Neural Reconstruction and Realistic Display of High Dynamic Range Images

High Dynamic Range (HDR) images can capture and display much richer appearance information than Low Dynamic Range (LDR) images, playing a vital role in image representation and visualization. In this talk, we discuss the neural reconstruction of HDR content from single and multiple LDR images, as well as specific aspects of high-fidelity reproduction of HDR content on LDR displays.

Initially, we introduce a generative model for HDR images, trained exclusively on diverse LDR image datasets in a fully unsupervised fashion. Leveraging exposure variations within these datasets, which implicitly contain information about the underlying distribution of HDR images, we propose the GlowGAN approach. This method enables the generation of extensive HDR image datasets and the reconstruction of HDR content from individual LDR images, aligning with the unsupervised inverse tone mapping (ITM) task, which generates believable details for overexposed areas. Secondly, we propose a novel approach that combines implicit neural representations with an expressive camera model to reconstruct an all-in-focus HDR image from an image stack. By skillfully mixing components of the stack across different focal distances, apertures, and exposure times, we achieve better results than those obtained with commonly used homogeneous focal or exposure stacks, which are more redundant for neural reconstruction. Finally, we focus on faithfully reproducing material gloss–a challenging task given the limited dynamic range, peak luminance, and 3D capabilities of display devices. Through psychophysical experiments on a wide range of 3D printed samples and their corresponding HDR photographs, we quantify changes in gloss appearance due to display limitations. These measurements inform adjustments to material reflectance parameters within a rendering system, aiming to improve the fidelity of gloss representation between real objects and their visualization on display devices.

Karol Myszkowski is a senior researcher and a group leader at the MPI Informatik, Saarbruecken, Germany. In the period from 1993 to 2000, he served as an associate professor in the Department of Computer Software at the University of Aizu, Japan. He received his PhD (1991) and habilitation (2001) degrees in computer science from Warsaw University of Technology (Poland). In 2011, he was awarded a lifetime professor title by the President of Poland. His research interests include global illumination and rendering, perception issues in graphics, high dynamic range imaging, computational photography, and stereo 3D. He co-authored the book “High Dynamic Range Imaging” and participated in various committees and editorial boards. Recently, he was a technical paper chair for ACM SIGGRAPH Asia 2020, and co-chair at EUROGRAPHICS 2023.

4D Aspects of Computational Microscopy: Vignetting, Aberrations, Rays and Waves

Ivo Ihrke will talk about 4D effects in optical imaging, in particular, joint field and pupil-dependent effects that are typically ignored in the corresponding theoretical treatments. He’s group has been implementing a variety of light field microscopes as well as other light field systems and is currently working on Fourier Ptychography, which is also a 4D imaging technique. He will draw connections and discuss the relation between the underlying wave and ray pictures of image formation, as well as the interpretation of aberrations and radiometric properties of the systems. A deeper understanding of the issues enables the improvement of primary data as well as the characterization of the optical systems.

Ivo Ihrke is professor of Computational Sensing at University of Siegen, Germany. Prior to joining Siegen, he was a staff scientist at the Carl Zeiss research department, which he joined on-leave from Inria Bordeaux Sud-Ouest, where he was a permanent researcher. At Inria he lead the research project “Generalized Image Acquisition and Analysis” which was supported by an Emmy-Noether fellowship of the German Research Foundation (DFG). Prior to that he was heading a research group within the Cluster of Excellence “Multimodal Computing and Interaction” at Saarland University.

He was an Associate Senior Researcher at the MPI Informatik, and associated with the Max-Planck Center for Visual Computing and Communications. Before joining Saarland University he was a postdoctoral research fellow at the University of British Columbia, Vancouver, Canada, supported by the Alexander von Humboldt-Foundation. He received a MS degree in Scientific Computing from the Royal Institute of Technology (KTH), Stockholm, Sweden and a PhD (summa cum laude) in Computer Science from Saarland University. 

Prof. Ivo Ihrke is interested in all aspects of Computational Imaging, including theory, mathematical modeling, algorithm design and their efficient implementation, as well as hardware concepts and their experimental realization and characterization.