Python Video Stabilizer Using Low Pass Filter

问题

I have a project which i should implement a video stabilizer using fft and filters (lpf or hpf)

Here is some part of the code that i want to modify it:

import cv2
import numpy as np

# Create a VideoCapture object and read from input file
cap = cv2.VideoCapture('Vibrated2.avi')

# load data
data = np.loadtxt('Vibrated2.txt', delimiter=',')

# Define the codec and create VideoWriter object
frame_width = int(cap.get(3))
frame_height = int(cap.get(4))
out = cv2.VideoWriter('Stabilized.avi',cv2.VideoWriter_fourcc('M','J','P','G'), 25, (frame_width,frame_height))

# Check if camera opened successfully
if (cap.isOpened()== False): 
  print("Error opening video stream or file")

def transform(frame, param):
  ti = cv2.getRotationMatrix2D((0,0), 0, 1)
  ti[0,2] += param[0]
  ti[1,2] += param[1]
  frame = cv2.warpAffine(frame, ti, frame.shape[1:-4:-1])
  return frame

num = 0 
# Read until video is completed
while(cap.isOpened()):
  # Capture frame-by-frame
  ret, frame = cap.read()
  if ret == True:
    # apply transformation
    frame = transform(frame, data[num])
    print (frame, "dn")
    num+=1

    # Display the resulting frame
    cv2.imshow('Frame',frame)

    # Write the frame into the file 'output.avi'
    out.write(frame)

    # Press Q on keyboard to  exit
    if cv2.waitKey(25) & 0xFF == ord('q'):
      break

  # Break the loop
  else: 
    break

# When everything done, release the video capture object
cap.release()

# Closes all the frames
cv2.destroyAllWindows()

There is a video named Vibrated1.avi And a text file which includes frames difference named Virated1.txt and it is looked like this:

0.341486, -0.258215

0.121945, 1.27605

-0.0811261, 0.78985

,...

I don't know how and where should i add some filters to this code to remove video vibration

Could anyone help me ?

回答1:

I can write short pseudocode with C++ parts:

cv::Mat homoFiltered = cv::Mat::eye(3, 3, CV_32F);
const double alpha = 0.9;
cv::Mat a1 = cv::Mat::eye(3, 3, CV_32F) * alpha;
cv::Mat a2 = cv::Mat::eye(3, 3, CV_32F) * (1. - alpha);


while cap >> frame:
    cv::Mat homo = CalcHomography(frame)
    homoFiltered = a1 * (homoFiltered * homo) + a2 * homo;
    cv::warpPerspective(..., homoFiltered, ...)

alpha - low pass smoothing coefficient in [0; 1]

a1 and a2 - matrices for applying alpha and (1 - alpha) to the transformation matrix

homoFiltered - filtered transformation matrix

homo - current matrix between Frame(t-1) and Frame(t)

来源：https://stackoverflow.com/questions/54368246/python-video-stabilizer-using-low-pass-filter

标签

python