Anisotropic Filtering Based on the WY Distribution and Multiscale Energy Concentration Accumulation Method for Dim and Small Target Enhancement

In ground-based infrared optical remote sensing systems, the target signal is very weak due to the dynamic strong light background and the movement of dim and small targets. To improve the limit detection capability, background suppression and target enhancement methods are required to be more suitable for this scenario. To solve this problem, we first analyze the image features in the current scene and propose a more complete point target and noise model. Then, we propose a new WY distribution function based on the Fermi–Dirac distribution function and propose an anisotropic filtering method based on this function, which further suppresses the background through the difference results of two steps. Building on the distribution function, we further designed an energy concentration accumulation strategy in nine scaled directions, through which the SNR of the target is effectively improved, and the suppression ability of the background is enhanced. In this dynamic scenario, the method can still detect targets with an average minimum SNR of 0.76. Through quantitative and qualitative experimental analysis, the proposed method has better robustness against extremely weak targets and dynamic backgrounds compared to the same type of algorithms.