说明：  这是一个由我本人亲自编写的提取图像特定部分的MATLAB程序。通过使用这个函数，你可以轻而易举地将图像的特定位置用白色矩形线框加以圈定、显示。
(If you want to circle the specific area of an image, this little program is much more practical and convenient, thus will help you to mark any area of the image with with rectangle.)