Finding the displacement from the image sequences/frames

I have a MP4 video which has a moving object. From the video, i have extracted the frames of about 960. From the extracted frames, have to select a rectangular roi with centroid point. From the centroid selected, i want to find the x and y displacement. How can I proceed further?

[Image Analyst]

How are you specifying the rectangular roi? Why should it change from one frame to the next. You're leaving out some needed information. In the meantime, see my attached demo where I measure the mean RGB in each frame. Just put the centroid into vectors or an matrix where you index it as a function of frame number, then use diff() or sqrt() to get distances the centroid moved from each frame to the next.

[Samraja]

I want to select a rectangular roi with centroid in the video. How can i specify to select the roi for the whole video?.

In the video, the selected roi is moving with time. So i want to find the x and y distances moved from each frame to next. How can I do?