The Modulo Radon Transform: Theory, Algorithms and Applications

TL;DR

This paper introduces the Modulo Radon Transform (MRT), a novel mathematical model and hardware-algorithmic approach for single-shot high dynamic range tomography with mathematical guarantees and experimental validation.

Contribution

It presents the first rigorous mathematical analysis and hardware-algorithmic framework for HDR tomography using the Modulo Radon Transform, enabling single-shot high dynamic range imaging.

Findings

Mathematical analysis of MRT including injectivity and inversion.

Experimental demonstration using custom modulo hardware.

Reconstruction results show advantages over traditional methods.

Abstract

Recently, experiments have been reported where researchers were able to perform high dynamic range (HDR) tomography in a heuristic fashion, by fusing multiple tomographic projections. This approach to HDR tomography has been inspired by HDR photography and inherits the same disadvantages. Taking a computational imaging approach to the HDR tomography problem, we here suggest a new model based on the Modulo Radon Transform (MRT), which we rigorously introduce and analyze. By harnessing a joint design between hardware and algorithms, we present a single-shot HDR tomography approach, which to our knowledge, is the only approach that is backed by mathematical guarantees. On the hardware front, instead of recording the Radon Transform projections that my potentially saturate, we propose to measure modulo values of the same. This ensures that the HDR measurements are folded into a lower dynamic range. On the algorithmic front, our recovery algorithms reconstruct the HDR images from folded measurements. Beyond mathematical aspects such as injectivity and inversion of the MRT for different scenarios including band-limited and approximately compactly supported images, we also provide a first proof-of-concept demonstration. To do so, we implement MRT by experimentally folding tomographic measurements available as an open source data set using our custom designed modulo hardware. Our reconstruction clearly shows the advantages of our approach for experimental data. In this way, our MRT based solution paves a path for HDR acquisition in a number of related imaging problems.