Cannot turn on Mac Webcam through OpenCV python

Question

I am new to opencv and trying to access my Macbook's built-in camera through OpenCV python but it gives an error.

import cv2

frameWidth = 640
frameHeight = 480
cap = cv2.VideoCapture(0)
cap.set(3, frameWidth)
cap.set(4, frameHeight)
cap.set(10,150)

while True:
   success, img = cap.read()
   cv2.imshow("Result", img)
   if cv2.waitKey(1) & 0xFF == ord('q'):
       break

Traceback (most recent call last):
  File "/Users/hasanaktas/PycharmProjects/OpencvPython/project3.py", line 12, in <module>
    cv2.imshow("Result", img)
cv2.error: OpenCV(4.2.0) /Users/travis/build/skvark/opencv-python/opencv/modules/highgui/src/window.cpp:376: error: (-215:Assertion failed) size.width>0 && size.height>0 in function 'imshow'

already tried changing VideoCapture(0) to VideoCapture(1) and adding the following code but still didn't help. Btw using PyCharm

cap.release()
cv2.destroyAllWindows()

Appendage

What is cap.set(10,150)? Try to avoid ugly constants like that and use the parameter names defined for you. – Shortterm

How are you calling it? I was told at work that Apple recently blocked anything that was not signed by an Apple Developer from accessing any of the peripherals. This gave us problems because it would not let Audacity access the mic. We had to build a shell script wrapper around it. Bash was signed so the bash script that called audacity was allowed to access the mic. – Sheeb

I don't recommend using the opencv video streaming functions with Apple devices; I've never gotten them to work. Instead, maybe consider streaming from an AVCaptureSession and sending the individual frames to your function. After all, a video is merely a series of individual images. Try using the UIImageToMat function (you may have to use the c++ library). – Geneviegenevieve

Answer 1

I had the same issue on my Mac. I simply replaced

cv2.VideoCapture(0)

with

cv2.VideoCapture(1)

works like a charm.

Jimmy

Answer 2

There are two suggestions I would like to mention.

#1: Enable your terminal or PyCharm to reach the camera.

---

• Go to System Preferences-> Security and Privacy -> Camera and add PyCharm to the list.

#2 Instead of while True use while cap.isOpened(), so you can know that PyCharm or terminal can access your camera.

• import cv2
  
  frameWidth = 640
  frameHeight = 480
  cap = cv2.VideoCapture(0)
  cap.set(3, frameWidth)
  cap.set(4, frameHeight)
  cap.set(10,150)
  
  while cap.isOpened():
      success, img = cap.read()
      if success:
          cv2.imshow("Result", img)
          if cv2.waitKey(1) & 0xFF == ord('q'):
              break
  

Dilettantism

what if it's not on the list? – Intermezzo

Answer 3

I had the same problem and I did not find any solution. By trial and error, I found that my OpenCV version is corrupted. As a result, I deleted it and install a new fresh one. You can use one of these two options: 1. Terminal run brew uninstall opencv3 to uninstall opencv then install it using sudo apt-get install libopencv-dev python-opencv command.

2. Anaconda Actually, I used this method for my own problem.

1. open anaconda
2. go to the environment section and select your environment as follow: then click on installed and search for opencv: select opencv package and uninstall it. then try to re-install opencv by selecting not installed and searching for opencv. be careful to install the correct version.

Araucania

Answer 4

Try to increase frame width/height, for example use:

frameWidth = 1048 frameHeight = 1028

Signac