Lucky Imaging Algorithm Research And Construction Of Real-time Processing System

Lucky imaging is a high-angular resolution astronomical image reconstruction technique that can effectively reduce the impact of atmospheri c turbulence on image quality and improve the imaging resolution of ground-based telescopes.Its key steps include image selection,registration and superposition.There are two types of algorithms for its implementation: space-domain algorithms and frequency-domain algorithms.This paper proposes a new lucky imaging algorithm,which uses the space-domain and frequency-domain selection ratios as a tie,and successfully combines the two basic lucky imaging algorithms of the space-domain and frequency-domain to make them a true subset.The experimental results show that under the same experimental data and experimental platform,the high-resolution restoration images obtained by this new algorithm are better than those obtained by the two basic algorithms.At the same time,this paper also presents a new method for selecting and storing good images,which can greatly save computer’s memory,so that the lucky imaging algorithm can not only be implemented on a general desktop or personal computer with small memory,but also be able to process more and larger astronomical images.On the other hand,the lucky imaging algorithms based on a central processing unit(CPU)encounter difficulty accomplishing real-time processing;thus,they are postprocessing 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 image selection algorithm without sorting,an optimal 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.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.