Python 3 +OpenCV + PyQt6 to display usbcam

A simple exercise run on Windows 11/Python 3.13.0 to capture images from usbcam display with GUI using OpenCV and PyQt6.

It's tested in Python virtual environment on Windows 11, with OpenCV aand PyQt6 installed.

pyqt6_cv2_usbcam.py, actually it's provided by MicroSoft Copilot.

import sys
import cv2
from PyQt6.QtWidgets import QApplication, QLabel, QWidget, QVBoxLayout
from PyQt6.QtGui import QImage, QPixmap
from PyQt6.QtCore import QTimer

class WebcamViewer(QWidget):
    def __init__(self):
        super().__init__()
        self.initUI()
        self.cap = cv2.VideoCapture(0)
        self.timer = QTimer(self)
        self.timer.timeout.connect(self.update_frame)
        self.timer.start(20)

    def initUI(self):
        self.setWindowTitle('Webcam')
        self.image_label = QLabel(self)
        layout = QVBoxLayout()
        layout.addWidget(self.image_label)
        self.setLayout(layout)

    def update_frame(self):
        ret, frame = self.cap.read()
        if ret:
            frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
            h, w, ch = frame.shape
            bytes_per_line = ch * w
            convert_to_Qt_format = QImage(frame.data, w, h, bytes_per_line, QImage.Format.Format_RGB888)
            self.image_label.setPixmap(QPixmap.fromImage(convert_to_Qt_format))

    def closeEvent(self, event):
        self.timer.stop()
        self.cap.release()
        event.accept()

if __name__ == '__main__':
    app = QApplication(sys.argv)
    viewer = WebcamViewer()
    viewer.show()
    sys.exit(app.exec())