In order to solve the problem of unclear images in the rough obstacle avoidance link of lunar landing in weak light environments， this study proposes two image preprocessing methods， namely "region" pixel binning and camera background value removal， to improve the imaging sensitivity， image signal-to-noise ratio （SNR）， and contrast ratio of lunar landing. First， based on the analysis of the principle of traditional pixel binning， a region pixel binning method based on the n_taps imaging data format is proposed. Then， according to the characteristics of large-scale obstacle recognition in lunar landing rough obstacle avoidance， the image contrast is improved by removing the background value of the camera. Finally， the methods of pixel binning， camera background removal， and the combination of the two methods are repeated using two cameras that have wide and narrow fields of view. The experimental results show that the SNR and contrast of images can be improved effectively by combining pixel merging and camera background value removal under weak light environments. In 2_Binning mode， the SNR and contrast of the camera with a wide field of view can be improved by 5.901 4 dB and 0.254 7， respectively， and the SNR and contrast of the camera with a narrow field of view can be improved by 5.764 4 dB and 0.265 4， respectively. In 4_Binning mode， the SNR and contrast of the camera with a wide field of view can be improved by 11.689 9 dB and 0.210 2， respectively， and the corresponding values for a camera with a narrow field of view can be improved by 11.401 5 dB and 0.284 0， respectively.