A night vision device and method for filtering a series of image frames that depict a moving subject, which thereby improves the signal-to-noise ratio of each image frame, is provided. A composite image is formed for each image frame by combining pixel values in a current image frame with pixel values in composite images corresponding to image frames acquired before the current image frame. Additionally, pixels values in image frames acquired subsequent to the acquisition of the current image frame are included when forming the composite image. A bi-directional recursive filter is used to weight the contributions from the previous composite images and subsequent image frames with a decay constant. Motion of the imaging system is optionally compensated for by establishing a moving reference frame and shifting the image frames to account for this motion; thus, registering the image frames before filtering the current image frame.