Research on the Evaluation Method of Reference free Clarity for Aerospace Optical Images

Aerospace optical systems play a crucial role in key fields such as Earth observation and deep space exploration. As a key indicator for measuring the performance of aerospace optical systems, image quality directly affects the success rate of measurement and control tasks and the availability of data. This article aims to compare and analyze different methods for evaluating the clarity of non reference images, mainly including five function methods based on gradient information, two transformation methods based on frequency domain, and a method based on information entropy. Then, the algorithms are simulated and compared using real optical sequence images of the International Space Station. Through the analysis of the evaluation values and curves, it is concluded that: 1) The EOG function, Tenengrad function, and Brenner function based on gradients are basically consistent with human perception, and the clarity evaluation effect is good; 2) The evaluation value data obtained from the Variance variance function, Laplace function, and frequency domain based method are relatively similar and cannot accurately evaluate the clarity of the image; 3) The evaluation method based on information entropy is not suitable for the clarity evaluation of such images.