CODEWITHSUNDEEP
pythonopencvpathgoogle-colaboratory
SHREYA SHANKAR
SHREYA SHANKAR

Reputation: 11

How do i solve this TypeError: 'NoneType' object is not subscriptable?

cap = cv2.VideoCapture(0)
while 1:
    ret,img = cap.read()
    image = cv2.imread('/content/drive/MyDrive/signProject/amer_sign2.png')
    cv2_imshow(image)
    img = cv2.flip(img, 1)
    top, right, bottom, left = 75, 350, 300, 590
    roi = img[top:bottom, right:left]
    roi=cv2.flip(roi,1)
    gray = cv2.cvtColor(roi, cv2.COLOR_BGR2GRAY)
    gray = cv2.GaussianBlur(gray, (7, 7), 0)
    cv2_imshow(gray)
    alpha=classify(gray)
    cv2.rectangle(img, (left, top), (right, bottom), (0,255,0), 2)
    font=cv2.FONT_HERSHEY_SIMPLEX
    cv2.putText(img,alpha,(0,130),font,5,(0,0,255),2)
    #cv2.resize(img,(1000,1000))
    cv2_imshow(img)
    key = cv2.waitKey(1) & 0xFF
    if key==ord('q'):
        break;
cap.release()
cv2.destroyAllWindows()

--------------------------------------------------------------------------- 
TypeError                                 Traceback (most recent call last) <ipython-input-36-105ee52e9f68> in <module>()
      6     img = cv2.flip(img, 1)
      7     top, right, bottom, left = 75, 350, 300, 590
----> 8     roi = img[top:bottom, right:left]
      9     roi=cv2.flip(roi,1)
     10     gray = cv2.cvtColor(roi, cv2.COLOR_BGR2GRAY)

TypeError: 'NoneType' object is not subscriptable

code

error

Upvotes: 1

Views: 5427

Answers (2)

Bjoergermeister
Bjoergermeister

Reputation: 31

The error means you are trying to index an object which can't be indexed (in this case a NoneType). So img in line 8 seems to be None. This is probably due to ret, img = cap.read() failing. The first return value in cap.read() (in your case called ret) indicates whether or not cap.read() was sucessful. You should check if ret is True before using img.

Why is cap.read() failing?

There could be a couple of reasons why it fails. Here's what I would do to find the cause of the problem:

Try other indices

I read a couple of times that cameras in OpenCV are not always at index 0, but may as well be at -1 or some other positive index.

Check if FFMPEG codec is installed

You need the FFMPEG codec to read video with OpenCV. You can print OpenCV Build Information with print(cv2.getBuildInformation()). It should show a section labelled Video I/O. In that section there should be an entry labelled FFMPEG, which is either YES or NO. If it's NO, you need to install OpenCV with FFMPEG

Verify that your camera works

In case you're using an external camera, make sure it's properly connected and working (e.g by using it with another program).

Upvotes: 2

elbe
elbe

Reputation: 1508

The error message means that, for some reason, img is equal to None, so roi = img[top:bottom, right:left] triggers the error.

Upvotes: 0

Related Questions