输入二值图像，可以测出图像中前景元素的大小。有三种测量方式，分别是最小包络矩形、标准（水平）包络矩形和给定方向包络矩形。基于opencv。-Input binary image, the image can be measured in the size of foreground elements. There are three measurement methods, namely, the smallest rectangular envelope, standard (horizont