  /**  * <p>Constructs the image pyramid which can be passed to "calcOpticalFlowPyrLK".</p>  *  * @param img 0-bit input image.  * @param pyramid output pyramid.  * @param winSize window size of optical flow algorithm. Must be not less than  * <code>winSize</code> argument of "calcOpticalFlowPyrLK". It is needed to  * calculate required padding for pyramid levels.  * @param maxLevel 0-based maximal pyramid level number.  * 