报错为：
cv2.error: OpenCV(4.5.5) D:aopencv-pythonopencv-pythonopencvmodulesimgprocsrccolor.cpp:182: error: (-215:Assertion failed) !_src.empty() in function ‘cv::cvtColor’
摄像头调用出现问题
解决方法：self.cap = cv2.VideoCapture(0)
改为：
self.cap = cv2.VideoCapture(0,cv2.CAP_DSHOW)
