opencv2 名称错误：未定义名称'output'

Question

** Python cv2 opencv2 live cam 不打开界面只显示灰色图像界面...这个开放的相机界面，但不是实时视频..........**

import cv2
def main():
windowName = "Live video Feed"
cv2.namedWindow(windowName)
cap = cv2.VideoCapture(0)
if cap.isOpened():
ret, frame = cap.read()
else:
ret = False
while ret:
ret, frame = cap.read()
cv2.imshow("Gray", output)
cv2.imshow(windowName, frame)
if cv2.waitKey(1) == 27:
break
cv2.destroyAllWindow()

cap.release()

if __name__== "__main__":
main() 

嗡嗡...

Traceback (most recent call last):
File "C:UsersLenovoDesktoplive webcame pro.py", line 32, in <module>
main()
File "C:UsersLenovoDesktoplive webcame pro.py", line 20, in main
cv2.imshow("Gray", output)
NameError: name 'output' is not defined
>>> 

Answer 1

while ret:
ret, frame = cap.read()

将此脚本添加到

output = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY) 

之间

cv2.imshow("Gray", output)
cv2.imshow(windowName, frame)
if cv2.waitKey(1) == 27:
break

Answer 2

while ret:
ret, frame = cap.read()

仅在下一行之后添加此内容。

output = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)