Single-pixel shadowless imaging by a ring detector

Active single-pixel imaging technology has shown significant advantages in many fields. However, its dependence on a single light source often leads to shadow artifacts, which reduces the imaging quality. Inspired by surgical shadowless lamps, this study proposes an innovative solution based on a ring detector to overcome this limitation. Taking advantage of the fact that the field of view of active single-pixel imaging depends on the projected pattern area, we explored multiple methods to construct a ring detector consisting of eight detectors. Specifically, eight independent detectors capture images with different shadows, and the shadowless effect is achieved by signal and image superposition. A simpler method is to connect eight detectors in series or in parallel to achieve shadowless imaging in a single acquisition. In addition, we combine a large-area ring detector with an active Bayer-Fourier pattern to achieve shadowless color imaging. Through a simple restoration algorithm, we simplify data processing and successfully separate and reconstruct the red, green, and blue color components. We expect that this simple shadowless imaging technology will have a wide range of applications in fields such as medical imaging and industrial inspection.