code: private int getOrientedJDiff(RasterTile tile1, RasterTile tile2) {
  		double dy = tile2.getBounds().getY() - tile1.getBounds().getY();
  		int dj = tile2.getCode().getY() - tile1.getCode().getY();
  		return (dj * dy) > 0 ? dj : -dj;
  	}
docs: Returns the difference in j index, taking orientation of y-axis into account. Some layers (WMS 1.8.0) have
  different j-index orientation than screen coordinates (lower-left = (0,0) vs upper-left = (0,0)).
  
  @param tile1 tile
  @param tile2 tile
  @return +/-(j2-j1)