I have a video of a man walking.I need to bring this man in middle keeping his motion intact. i.e. appears to be walking but stays at same place

</matlabcentral/answers/uploaded_files/60047/001-bg-01-090-041.png> It's in black and white silhouette form. (Man-White, Rest-Black). This man is walking from first frame to last frame, from right to left. I want him to always be in center, but he should appear to be moving. Such that it looks like he is walking on a treadmill.

I did the cropping part with the help of @Image Analyst. I don't know how to fix the centroid at one point, so that the person doesn't appear to vibrate. Also I cant make movie as all bounding boxes are not equal. Here is the code till now

 clc;
close all;
clear all;
video_read = VideoReader('D:\PROJECT M.Tech\Databases\Videos\DATA SET B\009\bg-01\090\090.avi');
numframes = video_read.NumberOfFrames;
for j= 1:numframes
  frame=read(video_read,j);
  im=rgb2gray(frame);
  im = bwareaopen(im,50); 
  siz=size(im); % image dimensions
  % Label the disconnected foreground regions (using 8 conned neighbourhood)
  L=bwlabel(im,8);
  % Get the bounding box around each object
  bb=regionprops(L,'BoundingBox');
  % Crop the individual objects and store them in a cell
  n=max(L(:)); % number of objects
  ObjCell=cell(n,1);
  for i=1:n
    % Get the bb of the i-th object and offest by 2 pixels in all
    % directions
    bb_i=ceil(bb(i).BoundingBox);
    idx_x=[bb_i(1)-2 bb_i(1)+bb_i(3)+2];
    idx_y=[bb_i(2)-2 bb_i(2)+bb_i(4)+2];
    if idx_x(1)<1, idx_x(1)=1; end
    if idx_y(1)<1, idx_y(1)=1; end
    if idx_x(2)>siz(2), idx_x(2)=siz(2); end
    if idx_y(2)>siz(1), idx_y(2)=siz(1); end
    % Crop the object and write to ObjCell
    im=L==i;
    ObjCell{i}=im(idx_y(1):idx_y(2),idx_x(1):idx_x(2));
  end
  % Visualize the individual objects
  figure
  for i=1:n
    subplot(1,n,i)
    imshow(ObjCell{i})
  end
  %bbox=regionprops(frame_im,'BoundingBox')
  F(j)=getframe;
end