python 2.7 and opencv code gives cvtcolor error

Question

faceCascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')

video_capture = cv2.VideoCapture(0) 

while True:


ret, frame = video_capture.read()

gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

faces = faceCascade.detectMultiScale(
    frame,
    scaleFactor=1.1,
    minNeighbors=5,
    minSize=(30, 30),
    flags=cv2.cv.CV_HAAR_SCALE_IMAGE
)

# Draw a rectangle around the faces
for (x, y, w, h) in faces:
    cv2.rectangle(frame, (x, y), (x+w, y+h), (0, 255, 0), 2)

# Display the resulting frame
cv2.imshow('Video', frame)

if cv2.waitKey(1)==ord('e'):
    break

code gives this error, please help me

Traceback (most recent call last): File "C:\Users\yavuz\Desktop\sor\sor2.pyw", line 15, in gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY) error: ........\opencv\modules\imgproc\src\color.cpp:3737: error: (-215) scn == 3 || scn == 4 in function cv::cvtColor

Answer 1

You need to check if "ret == True' before going on with cvtColor. The code should look like this:

faceCascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')

video_capture = cv2.VideoCapture(0)

while True:

    ret, frame = video_capture.read()

    if ret == True:

        gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

        faces = faceCascade.detectMultiScale(
            frame,
            scaleFactor=1.1,
            minNeighbors=5,
            minSize=(30, 30),
            flags=cv2.cv.CV_HAAR_SCALE_IMAGE
        )

        # Draw a rectangle around the faces
        for (x, y, w, h) in faces:
            cv2.rectangle(frame, (x, y), (x+w, y+h), (0, 255, 0), 2)

        # Display the resulting frame
        cv2.imshow('Video', frame)

        if cv2.waitKey(1)==ord('e'):
            break