I. Introduction
Target detection technology based on infrared band has always been a hot topic in the field of target tracking because of its small influence by external illumination and its ability to work in various weather conditions. However, the target in infrared image is greatly affected by clutter and complex background, so the detection accuracy of dim targets is often poor. Therefore, in order to improve the accuracy of dim target recognition, background suppression is needed to enhance the contrast between target and ambient noise.