opencv error Assertion failed python

This typically happens to me when the filename doesn't exist or isn't an image.

This is happening because there is an error in reading image from the video. you can try the below code and if you are seeing nothing, then the problem is with your webcam.

import cv2 cap = cv2.VideoCapture(0) ret, frame = cap.read() while ret: # Our operations on the frame come here gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY) # Display the resulting frame cv2.imshow('frame',gray) ret, frame = cap.read() if cv2.waitKey(1) & 0xFF == ord('q'): break # When everything done, release the capture cap.release() cv2.destroyAllWindows() 

If you are using a docker container to run your code, the issue might be in the way you set up your docker container. In particular, you need to specify a flag --device to enable a camera usage in the docker container when creating the container like this:

docker run --device <device-path> <rest-of-the-paramaters> 

Before that, you need to check the path of the camera device by using ls -ltrh /dev/video* for Ubuntu. Usually, the path is /dev/video0.

I ran your code, it works perfectly fine for me. But I did get some indentation errors.

Here's the updated code:

import numpy as np import cv2 cap = cv2.VideoCapture(0) while(True): # Capture frame-by-frame ret, frame = cap.read() # Our operations on the frame come here gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY) # Display the resulting frame cv2.imshow('frame',gray) if cv2.waitKey(1) & 0xFF == ord('q'): break # When everything done, release the capture cap.release() cv2.destroyAllWindows() 

If one still gets this error, try doing the following:

• check if your webcam works fine with any other library other than OpenCV
• change VideoCapture(0) => VideoCapture(1)
• Uninstall OpenCV and reinstall it
• Relaunch your code editor or whatever
• Switch to a different IDE (for example from PyCharm to Jupyter notebook)
• Also add these in the above code :

 if ret: assert not isinstance(frame,type(None)), 'frame not found' 

OR

assert (frame is not None) == ret, (ret, type(frame))

OR

 if not ret: print("Can't receive frame (stream end?). Exiting ...") break