今天简单来看一下OpenCV中的边界填充
@param src Source image.
@param dst Destination image of the same type as src and the size Size(src.cols+left+right,
src.rows+top+bottom) .
@param top the top pixels
@param bottom the bottom pixels
@param left the left pixels
@param right Parameter specifying how many pixels in each direction from the source image rectangle
to extrapolate. For example, top