Extended Depth-of-Field Lensless Imaging Using an Optimized Radial Mask

José Reinaldo C. S. A. V. S. Neto, Tomoya Nakamura, Yasushi Makihara, Yasushi Yagi

Abstract: The freedom of design of coded masks used by mask-based lensless cameras is an advantage these systems have when compared to lens-based ones. We leverage this freedom of design to propose a shape-preserving optimization scheme for a radial-type amplitude coded mask. Due to the depth-independency of the radial mask's point spread function, they can be used for extending the effective depth of field (DOF) of a lensless imaging system. In this article we optimized a coded mask for improved frequency response, while retaining its radial characteristics and therefore extended-DOF capabilities. We show that our optimized radial mask achieved better overall frequency response when compared to naive implementations of a radial mask. We also quantitatively and qualitatively demonstrated the extended DOF imaging achieved by our optimized radial mask in simulations by comparing it to different non-radial coded masks. Finally, we built a prototype camera to validate the extended DOF capabilities of our coded mask in real scenarios.