导入picamera的轻微问题会给我一个版权错误，并且会涉及多个名称等问题，而./pngview会给我一个无效的代码
我是否需要从https://github.com/waveform80/picamera下载文件才能正常工作？
还有一点需要注意的是python 3是否可以对png覆盖进行编程？！
经过几次修改后，我的错误出现在这里：
Traceback (most recent call last):
File "/home/pi/ScriptTest.py", line 24, in <module>
o = camera.add_overlay(pad.tobytes(), size=img.size)
File "/usr/lib/python3/dist-packages/picamera/camera.py", line 891, in add_overlay
self._check_camera_open()
File "/usr/lib/python3/dist-packages/picamera/camera.py", line 540, in _check_camera_open
raise PiCameraClosed("Camera is closed")
picamera.exc.PiCameraClosed: Camera is closed
这是我从github上的pi摄像机信息中键入的代码：
from PIL import Image
from time import sleep
with picamera.PiCamera() as camera:
camera.start_preview()
# Load the arbitrarily sized image
img = Image.open('/home/pi/Pictures/Overlay.png')
# Create an image padded to the required size with
# mode 'RGBA'
pad = Image.new('RGBA', (
((img.size[0] + 31) // 32) * 32,
((img.size[1] + 15) // 16) * 16,
))
# Paste the original image into the padded one
pad.paste(img, (0, 0), img)
# Add the overlay with the padded image as the source,
# but the original image's dimensions
o = camera.add_overlay(pad.tobytes(), size=img.size)
# By default, the overlay is in layer 0, beneath the
# preview (which defaults to layer 2). Here we make
# the new overlay semi-transparent, then move it above
# the preview
o.alpha = 255
o.layer = 3
self._check_camera_open()
# Wait indefinitely until the user terminates the script
while True:
sleep(1)```