Lucky imaging is a high-angular resolution astronomical image reconstruction technique that can effectively reduce the impact of atmospheric turbulence on image quality and improve the imaging resolution of ground-based telescopes. Its key steps include image selection, registration and superposition. However, the lucky imaging algorithms based on a central processing unit (CPU) encounter difficulty accomplishing real-time processing; thus, they are post-processing methods and cannot meet the needs of on-site observers. Taking advantage of the parallelism and flexibility of the field programmable gate array (FPGA), this paper presents a new real-time lucky imaging algorithm that features real-time processing and dynamic updating and displaying. The algorithm consists of a dynamic sorting-free image selection algorithm, an improved registration and storage method, a parallel superposition algorithm, a parallel preprocessing method for noise suppression and cosmic ray removal, and a dynamic multithreshold display scheme. The simulation results show that the algorithm is feasible, effective and efficient. Compared with other lucky imaging algorithms based on FPGAs, this algorithm shows great advantages in clock consumption and on-chip resource consumption. Furthermore, it can be implemented on a small or medium-size development board of an FPGA. Moreover, the implemented FPGA system can perform real-time and dynamic lucky imaging for more than 10,000 frames of short-exposure images with an original format of 512 × 512 pixels continuously. The experimental results not only show the validity of the proposed algorithm but also demonstrate the feasibility of the proposed implementation techniques for the FPGA-based algorithm.INDEX TERMS Astronomical observation, data reduction, FPGA, lucky imaging, real-time processing.
