基于灰度图的阴影消除，通过对水平方向的投影图的峰值，提取前景（投影值与峰值比小于阈值时认为是阴影）-Based on the grayscale of the shadow of the elimination of the horizontal direction of the projection of the peak, the prospects for extraction (projection value and the peak is less than the threshold considered to be a shadow)