Infrared weak and small target detection method and system based on point spread function fitting

The invention relates to an infrared weak and small target detection method and system based on point spread function fitting, belongs to the field of target detection, and solves the problem that the prior art does not consider inherent characteristics of an infrared optical system and is difficult to adapt to contrast reduction and image gray gradient distortion caused by uniformity reduction of an infrared detector. After a point spread function distribution model is established, an Otsu method is utilized to calculate an initial threshold value of a target background; determining a target center, taking the target center as the centroid of rectangles, taking integral multiples of the transverse length and the longitudinal length of the target as the side length of the rectangles, respectively taking a large rectangle and a small rectangle, and taking a region between the two rectangles as a background region to calculate iterative values of variances of gray values of all pixels; and identifying target pi