Assertion Failed on OPENCV cvtColor

[diogobernini]

So, I had a problem here with my camera (it broke) and I bought a new one, same model, same brand. Plugged it in and got an error. Tried again on your code, same error. Not sure if it's a driver problem, since I'm using the exact same camera. Maybe the power is not being enough? I'll check on that on my side.

OpenCV Error: Assertion failed (scn == 3 || scn == 4) in cvtColor, file /usr/src/packages/BUILD/opencv-2.4.1+dfsg/modules/imgproc/src/color.cpp, line 3149
ERROR:tornado.application:Exception in callback <bound method WebSocket.loop of <__main__.WebSocket object at 0x284e5b0>>
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/tornado/ioloop.py", line 1020, in _run
    return self.callback()
  File "server.py", line 94, in loop
    img = Image.fromarray(cv2.cvtColor(frame, cv2.COLOR_BGR2RGB))
error: /usr/src/packages/BUILD/opencv-2.4.1+dfsg/modules/imgproc/src/color.cpp:3149: error: (-215) scn == 3 || scn == 4 in function cvtColor

I looked it up online and it was saying as if the frame is empty and then there is no conversion. So I feel like it could be a driver issue.

[diogobernini]

Nope, tried three different power sources for the PI, not the problem. Tested the camera on my PC, worked.

[diogobernini]

The following snippet is printing ten times "cannot read image", so it is definitely a driver problem on my side:

import cv2
from PIL import Image
camera = cv2.VideoCapture(0)
for i in range (10):
    ret, img = camera.read()
    if ret:
        break
    else:
        print ("cannot read img");

Maybe we should add an if and read the first value on the tuple returned by camera.read() (line 7x on your code I think), printing an understandable error to the developer. What's your opinion?

[diogobernini]

And for my problem, I'll try a clean install of raspbian and see what happens.

[patrickfuller]

Maybe we should add an if and read the first value on the tuple returned by camera.read() (line 7x on your code I think), printing an understandable error to the developer. What's your opinion?

I think that's a good idea. Send over a pull request and I'll accept it.