I'm extracting the optical flow from a video using the Matlab Computer Vision Toolbox (I'm unfortunately not computer-savy enough to use C++ / OpenCV). The optical flow that is computed, peaks at regular time steps of 12 frames (the video is 25 frames/second). I use 7x7 patches, to deal with some of the normal video noise but I'm not sure what causes this 25/12 = 2.084 Hz behaviour, is it likely caused by the video or by the optical flow algorithm?
Also, what is the best way to get rid of it? I tried a notch filter to filter our this specific frequency, which seems to work if I look at the signal in the frequency domain (the spike at 2.084 disappears) but in the time-space domain, the signal still exhibits a regularity that I'd like to get rid of, is there a better way? Btw, I have a number of videos and they all exhibit the same issue.
Any thoughts or suggestions are welcome, thank you.
