LED array positional misalignment correction method based on superimposed images for Fourier ptychography

Fourier ptychographic microscopy (FPM) combines a wide field of view with high resolution, offering a powerful imaging technique. However, positional misalignments introduced during the assembly of the LED array often degrade the image reconstruction quality. In low-resolution sequences, images containing both bright and dark regions separated by an arc-shaped boundary-referred to as transition images-can be utilized to calibrate the positions of the LED array. In this paper, we propose a transition image imaging model that explains the formation of transition images. Using unbiased superimposed images generated at this height as ground truth, we further propose the superimposed image alignment (SIA) algorithm to calibrate the planar offset parameters of the LED array. Multiple simulations and experimental comparisons confirm the accuracy and robustness of the model and the SIA algorithm. In contrast, FPM reconstruction comparison experiments demonstrate the high precision correction capability of the SIA algorithm.