def resize_to_fill(ncols, nrows = nil, gravity = CenterGravity)
      copy.resize_to_fill!(ncols, nrows, gravity)
    end
def resize_to_fill(ncols, nrows = nil, gravity = CenterGravity)
      copy.resize_to_fill!(ncols, nrows, gravity)
    end
Force an image to exact dimensions without changing the aspect ratio.
 Resize and crop if necessary. (Thanks to Jerett Taylor!)