ABSTRACT
This Letter explores Fourier ptychography (FP) using epi-illumination. The approach effectively modifies the FP transfer function to be coherent-like out to the incoherent limit of twice the numerical aperture over the wavelength 2NA/λ. Images reconstructed using this approach are shown to have higher contrast at finer details compared with images using incoherent illumination, indicating that the FP transfer function is superior in high spatial frequency regions.
ABSTRACT
Traditional superresolution techniques employ optimizers, priors, and regularizers to deliver stable, appealing restorations even though deviating from the real, ground-truth scene. We have developed a non-regularized superresolution algorithm that directly solves a fully-characterized multi-shift imaging reconstruction problem to achieve realistic restorations without being penalized by improper assumptions made in the inverse problem. An adaptive frequency-based filtering scheme is introduced to upper bound the reconstruction errors while still producing more fine details as compared with previous methods when inaccurate shift estimation, noise, and blurring scenarios are considered.
ABSTRACT
Traditional fringe-projection three-dimensional (3D) imaging techniques struggle to estimate the shape of high dynamic range (HDR) objects where detected fringes are of limited visibility. Moreover, saturated regions of specular reflections can completely block any fringe patterns, leading to lost depth information. We propose a multi-polarization fringe projection (MPFP) imaging technique that eliminates saturated points and enhances the fringe contrast by selecting the proper polarized channel measurements. The developed technique can be easily extended to include measurements captured under different exposure times to obtain more accurate shape rendering for very HDR objects.
