Preview USB camera image

1. Implementation principle

Use cv2.VideoCapture() function to capture video from USB camera or video file.

2. Implementation effect

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cd ~/opencv

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python3 17.camera_preview_usb.py # The program opens video0 by default, open other cameras and modify the device number by yourself

Note: Select the camera screen and press q to exit the program!

3. Implementation code

​x
import cv2
​
def preview_usb_camera():
    cap = cv2.VideoCapture(0)
    if not cap.isOpened():
        print("Error: Could not open USB camera.")
        return
​
    while True:
        ret, frame = cap.read()
        if not ret:
            break
​
        cv2.imshow('USB Camera Preview', cv2.resize(frame, (640, 480)))
        if cv2.waitKey(1) & 0xFF == ord('q'):
            break
​
    cap.release()
    cv2.destroyAllWindows()
​
preview_usb_camera()