motion_detection.py

import cv2
import numpy as np


def main():
    """Detect motion using frame differencing."""
    cap = cv2.VideoCapture(0)
    if not cap.isOpened():
        print("Error: Could not open webcam")
        return

    print("Webcam opened successfully!")
    print("Press 'q' to quit")

    # Use a background subtractor for robust motion detection
    back_sub = cv2.createBackgroundSubtractorMOG2(history=500, varThreshold=25, detectShadows=True)

    while True:
        ret, frame = cap.read()
        if not ret:
            print("Error: Could not read frame")
            break

        # Apply background subtraction to detect motion
        fg_mask = back_sub.apply(frame)

        # Clean up the mask to reduce noise
        kernel = np.ones((3, 3), np.uint8)
        fg_mask = cv2.morphologyEx(fg_mask, cv2.MORPH_OPEN, kernel)
        fg_mask = cv2.morphologyEx(fg_mask, cv2.MORPH_DILATE, kernel, iterations=2)

        # Highlight the motion on the original frame
        motion_highlight = cv2.bitwise_and(frame, frame, mask=fg_mask)

        # Find contours of moving regions to draw bounding boxes
        contours, _ = cv2.findContours(fg_mask, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
        for contour in contours:
            if cv2.contourArea(contour) < 500:
                continue  # skip small clusters to reduce noise
            x, y, w, h = cv2.boundingRect(contour)
            cv2.rectangle(frame, (x, y), (x + w, y + h), (0, 255, 0), 2)
            cv2.putText(
                frame,
                "Motion",
                (x, y - 10),
                cv2.FONT_HERSHEY_SIMPLEX,
                0.5,
                (0, 255, 0),
                1,
                cv2.LINE_AA,
            )

        # Display the results
        cv2.imshow("Original", frame)
        cv2.imshow("Motion Mask", fg_mask)
        cv2.imshow("Motion Highlight", motion_highlight)

        if cv2.waitKey(1) & 0xFF == ord('q'):
            break

    cap.release()
    cv2.destroyAllWindows()


if __name__ == "__main__":
    main()