为了减少alpha-expansion算法的计算量，本文在标号为alpha的像素向其它像素膨胀的过程中，先隔离非alpha类间的联系，而只考虑alpha类与非alpha类之间的关系，从而避免alpha-expansion算法需要构造辅助结点的问题，减少了s/t图中边的数目，提高了算法的计算效率。因放松了非alpha类间的关系对alpha膨胀的约束，使得算法可以更容易得跳出能量函数的局部极小点而获得更优的分割结果。-In order to reduce alpha- expansion algorithm calculation, based on the label for alpha pixel to other pixel expansion process, first isolation than alpha between class relation, and only consider alpha class and the alpha relation between kind, so as to avoid alpha- expansion algorithm need to construct auxiliary node problem, reduce the s/t diagram of the number of edge, improve the computation efficiency of the algorithm. For relax the alpha class to the relationship between the constraints of alpha expansion, which makes the algorithm can be more easy to jump out of the energy function of the local minimum point and obtain better segmentation result.