我一直有这个问题 TypeError: 'NoneType' object is not subscriptable.在为手语编写代码 jupyter 时

Question

cap = cv2.VideoCapture(0)
while True:    
    ret, frame = cap.read()     
    frame=cv2.flip(frame, 1)    
    roi = frame[100:400, 320:620]
    cv2.imshow('roi', roi)
    roi = cv2.cvtColor(roi, cv2.COLOR_BGR2GRAY)
    roi = cv2.resize(roi, (28, 28), interpolation = cv2.INTER_AREA)    
    cv2.imshow('roi sacled and gray', roi)
    copy = frame.copy()
    cv2.rectangle(copy, (320, 100), (620, 400), (255,0,0), 5)    
    roi = roi.reshape(1,28,28,1)    
    result = str(model.predict_classes(roi, 1, verbose = 0)[0])
    cv2.putText(copy, getLetter(result), (300 , 100), cv2.FONT_HERSHEY_COMPLEX, 2, (0, 255, 0), 2)
    cv2.imshow('frame', copy)    
    if cv2.waitKey(1) == 13:
        break        
    cap.release()
    cv2.destroyAllWindows()

以上是为ASL的实时对象检测编写的代码。 我在第 10 行不断收到此错误：

<块引用>

TypeError: 'NoneType' 对象不可下标