code: protected void interpolateFlowScale(GrayF32 prev, GrayF32 curr) {
  		interp.setImage(prev);
  
  		float scaleX = (float)(prev.width-1)/(float)(curr.width-1)*0.999f;
  		float scaleY = (float)(prev.height-1)/(float)(curr.height-1)*0.999f;
  
  		float scale = (float)prev.width/(float)curr.width;
  
  		int indexCurr = 0;
  		for( int y = 0; y < curr.height; y++ ) {
  			for( int x = 0; x < curr.width; x++ ) {
  				curr.data[indexCurr++] = interp.get(x*scaleX,y*scaleY)/scale;
  			}
  		}
  	}
docs: Takes the flow from the previous lower resolution layer and uses it to initialize the flow
  in the current layer.  Adjusts for change in image scale.