detect image mime type

mime.py

name = 'image.jpg'

with open(name, 'rb') as f:
  content = f.read()

head = content[0:3].hex()
mime = 'jpg'
if head == '89504e': mime = 'png'
elif head == '474946': mime = 'gif'
# else head == 'ffd8ff': mime = 'jpg'
print(mime)