程序代码：

"""
    复制图片的上下二部分,保存成二个文件
"""
import os

filename = "./456.jpg"
filesize = os.path.getsize(filename)

def work():
    with open(filename, "rb") as fr:
        with open('./top.jpg','wb') as fw1:
            data = fr.read(filesize//2) # 复制图片上半部分
            fw1.write(data)
        with open('./bom.jpg','wb') as fw2:
            fr.seek(filesize // 2,0) # 复制图片下半部分
            data = fr.read()
            fw2.write(data)

work()