Webcam generated image distorted and python stop working

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Code:

import cv2
import sys

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

video_capture = cv2.VideoCapture(0)

img_counter = 0

while True:
    # Capture frame-by-frame
    ret, frame = video_capture.read()


    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    k = cv2.waitKey(1)
    faces = faceCascade.detectMultiScale(
        gray,
        scaleFactor=1.5,
        minNeighbors=5,
        minSize=(30, 30),
        flags=cv2.CASCADE_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('FaceDetection', frame)

    if k%256 == 27: #ESC Pressed
        break
    elif k%256 == 32:
        # SPACE pressed
        img_name = "facedetect_webcam_{}.png".format(img_counter)
        cv2.imwrite(img_name, frame)
        print("{} written!".format(img_name))
        img_counter += 1


# When everything is done, release the capture
video_capture.release()
cv2.destroyAllWindows()

running the code works fine, but after i try to installed CMake and dlib library which i failed to do the image of the webcam is distorted and python stop working