You can try to perform a Gaussian blur before sending the frame to backSub.apply() or experiment with the parameters for cv2.createBackgroundSubtractorMOG2(): if you need a better explanation of what they do, try this page.
This is the result from a 7x7 Gaussian blur using this video.
Code:
import cv2
import numpy as np
import sys
# read input video
cap = cv2.VideoCapture('traffic.mp4')
if (cap.isOpened()== False):
print("!!! Failed to open video")
sys.exit(-1)
# retrieve input video frame size
frame_width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
frame_height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
fps = cap.get(cv2.CAP_PROP_FPS)
print('* Input Video settings:', frame_width, 'x', frame_height, '@', fps)
# adjust output video size
frame_height = int(frame_height / 2)
print('* Output Video settings:', frame_width, 'x', frame_height, '@', fps)
# create output video
video_out = cv2.VideoWriter('traffic_out.mp4', cv2.VideoWriter_fourcc(*'MP4V'), fps, (frame_width, frame_height))
#video_out = cv2.VideoWriter('traffic_out.avi', cv2.VideoWriter_fourcc('M','J','P','G'), fps, (frame_width, frame_height), True)
# create MOG
backSub = cv2.createBackgroundSubtractorMOG2(history=5, varThreshold=60, detectShadows=True)
while (True):
# retrieve frame from the video
ret, frame = cap.read() # 3-channels
if (frame is None):
break
# resize to 50% of its original size
frame = cv2.resize(frame, None, fx=0.5, fy=0.5)
# gaussian blur helps to remove noise
blur = cv2.GaussianBlur(frame, (7,7), 0)
#cv2.imshow('frame_blur', blur)
# subtract background
fgmask = backSub.apply(blur) # single channel
#cv2.imshow('fgmask', fgmask)
# concatenate both frames horizontally and write it as output
fgmask_bgr = cv2.cvtColor(fgmask, cv2.COLOR_GRAY2BGR) # convert single channel image to 3-channels
out_frame = cv2.hconcat([blur, fgmask_bgr]) #
#print('output=', out_frame.shape) # shape=(360, 1280, 3)
cv2.imshow('output', out_frame)
video_out.write(out_frame)
# quick pause to display the windows
if (cv2.waitKey(1) == 27):
break
# release resources
cap.release()
video_out.release()
cv2.destroyAllWindows()