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Remove jitter in video stabilization

asked 2014-02-06 23:34:39 -0500

Jenny gravatar image

updated 2014-02-06 23:35:09 -0500

I am working on a video stabilization field. Now I calculate optical flow between 2 consecutive frames by using calcOpticalFlowPyrLK in opencv. After that, I use function estimateGlobalMotionRobust to get global motion parameters to warp the previous frame to new frame. But the result is not good. it is not stable as I desired. I read many documents for this stabilize purpose is need to remove jitter in global motion parameters. But I do not know how to... Some documents said that I should use Kalman filter, another use low pass filter, but I do not know to how to use them. Can you help me?

Here is my code:

VideoWriter writeOutputVideo ("out.avi",0,fps,cvSize(frameW,frameH),TRUE);



prevImg = currImg.clone();

currImg = grayImg.clone();

backupColorImg = colorImg.clone();




TermCriteria opticalFlowTermCriteria = TermCriteria(CV_TERMCRIT_ITER | CV_TERMCRIT_EPS,20,0.3);


std::vector<uchar> features_found;

std::vector<float> feature_errors;

calcOpticalFlowPyrLK( prevImg, currImg, cornerPrev, cornerCur, features_found, feature_errors ,Size( winSize, winSize ), 5,opticalFlowTermCriteria, 0 );

//Mat transformMatrix = estimateGlobalMotionLeastSquares(cornerPrev,cornerCur,AFFINE,0);
//Mat transformMatrix = findHomography(cornerPrev,cornerCur,0,3.0,noArray());
Mat transformMatrix = estimateGlobalMotionRobust(cornerPrev,cornerCur,3,RansacParams::affine2dMotionStd(),0,0);

warpPerspective(backupColorImg,outImg,transformMatrix,Size(frameW,frameH),INTER_NEAREST|WARP_INVERSE_MAP,BORDER_CONSTANT ,0);


imshow("Optical Flow",outImg);


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2 answers

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answered 2014-02-07 02:55:47 -0500

I don't think that KLT is the best algorithm for video stabilization... It's way too slow...

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Yes I see, but my purpose is be stable video, not care about the speed. Can you help me to fix the above problem, please?

Jenny gravatar imageJenny ( 2014-02-09 01:06:05 -0500 )edit

answered 2014-02-07 17:22:11 -0500

Nghia gravatar image

As a first step I would confirm that you are getting good optical flow by drawing them on the screen.

As a second step I would remove bad optical flow vectors before passing them into estimateGlobalMotionRobust. Just loop through features_found and keep the good ones. This may or may not not be necessary, but if you can make life easier for the function then why not.

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I already checked the optical flow. It 's exactly. But when I get the global motion parameter through transformMatrix variable to warp image, then the result video is not stable. I do not know why it is? How do you know the bad optical flow vectors?

Jenny gravatar imageJenny ( 2014-02-09 01:05:09 -0500 )edit

features_found is a vector containing "1" for good, "0" for bad. Would you be able to post the input video you use? That way we can see what's going on.

Nghia gravatar imageNghia ( 2014-02-09 05:17:05 -0500 )edit

Yes. My input video code is here. I read a video with format .avi from the computer.

   Mat currImg, prevImg, colorImg, outImg, grayImg, resultImg, backupColorImg;
if (!capture.isOpened())
    printf("Can not open the video file");
currImg = grayImg.clone();
outImg = grayImg.clone();

int winSize = 20;
int maxCorners = 200;

double qualityLevel = 0.01;
double minDistance = 5.0;
int blockSize = 3;

int fps = 30;
int frameW = grayImg.cols;
int frameH = grayImg.rows;
Jenny gravatar imageJenny ( 2014-02-09 05:40:54 -0500 )edit

What I meant was the video you use for testing, the file that you load in. Would you be able to upload the video file, or is too big?

Nghia gravatar imageNghia ( 2014-02-09 05:46:58 -0500 )edit

My video test: I uploaded it temporally

Jenny gravatar imageJenny ( 2014-02-09 06:06:32 -0500 )edit

That's a very low res video, might be hard to work with. Do you have one that is a bit higher resolution?

Nghia gravatar imageNghia ( 2014-02-09 06:56:16 -0500 )edit
Jenny gravatar imageJenny ( 2014-02-09 07:05:01 -0500 )edit
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Asked: 2014-02-06 23:34:39 -0500

Seen: 1,355 times

Last updated: Feb 07 '14