选择一幅黑白色类似于圆形的图片，运行后的A为黑色像素数，B为边界像素数，4*3.14*A/（B*B）即圆形度，此值越接近1，说明越像圆形，偏离1比如0.7，说明已经不算是圆形-Select a site similar to a circular black and white pictures, run after A black pixels, B for border pixels, 4* 3.14* A/(B* B) that is circular degrees, this value is more close to 1, note more like a round, such as the 0.7 deviation from the one that has not a circular