OpenCV_TypeError：'NoneType'对象没有属性'__getitem__'

Question

我正在使用OpenCV 2.4.6并从OpenCV Python教程中成功运行以下代码 -

    import numpy as np
import cv2
cap = cv2.VideoCapture('slow.flv')
ret,frame = cap.read()

r,h,c,w = 250,90,400,125  # simply hardcoded the values
track_window = (c,r,w,h)
roi = frame[r:r+h, c:c+w]
hsv_roi =  cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)
mask = cv2.inRange(hsv_roi, np.array((0., 60.,32.)), np.array((180.,255.,255.)))

roi_hist = cv2.calcHist([hsv_roi],[0],mask,[180],[0,180])
cv2.normalize(roi_hist,roi_hist,0,255,cv2.NORM_MINMAX)

term_crit = ( cv2.TERM_CRITERIA_EPS | cv2.TERM_CRITERIA_COUNT, 10, 1 )

while(1):
ret ,frame = cap.read()

if ret == True:
    hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)
    dst = cv2.calcBackProject([hsv],[0],roi_hist,[0,180],1)

    # apply meanshift to get the new location
    ret, track_window = cv2.meanShift(dst, track_window, term_crit)

    # Draw it on image
    x,y,w,h = track_window
    img2 = cv2.rectangle(frame, (x,y), (x+w,y+h), 255,2)
    cv2.imshow('img2',img2)

    k = cv2.waitKey(60) & 0xff
    if k == 27:
        break
    else:
        cv2.imwrite(chr(k)+".jpg",img2)

else:
    break

cv2.destroyAllWindows()
cap.release()

后来我开始使用OpenCV 3.0并替换站点包目录中的一些Lib文件，并替换了CV2.pyd文件。然后，当我尝试运行相同的代码时，我收到以下错误 -

追踪（最近一次通话）：   文件“D：\ Backup \ OpenCV_Python_Prac_files \ Prac5.1.1_ Video Analysis_MeanShift.py”，第14行，in     roi = frame [r：r + h，c：c + w] TypeError：'NoneType'对象没有属性'_ getitem _'

谁能告诉我造成这个问题的原因是什么？ 在此先感谢。

Answer 1

错误表明您的frame是None。检查第一次调用cap.read

的返回值