实现分水岭分割函数,需要给出待分割图片，和给定的种子点矩阵mask。该函数是依赖与opencv库，但是实现方法和opencv不同，该方法能够更好的保留元图片的轮廓信息。-An algorithm for watershed. This algorithm is realised through opencv library, but different　the algorithm of opencv. A better contour is achieved by my algorithm.