文件夹中含有子文件夹，修改子文件夹中的图像存储格式，把png图像改为jpg图像，python代码如下：
import os
import cv2
filePath = 'C:\\Users\\admin\\Desktop\\img'
for dirpath, dirnames, filenames in os.walk(filePath):
path = [os.path.join(dirpath, names) for names in filenames]
for str in path:
if str[-3:] == 'png':
tmp = cv2.imread(str)
cv2.imwrite(str[:-3] + 'jpg', tmp)
os.remove(str)