GUI开发：实时显示摄像头图像

import tkinter as tk
from PIL import Image, ImageTk
import cv2
import numpy as np
import time

g_exit = False

def close_window():
    global g_exit
    g_exit = True

def video_init():
    cap = cv2.VideoCapture(0)
    cap.set(3, 640)
    cap.set(4, 480)
    time.sleep(2)
    return cap

def video_show():
    cap = video_init()
    while (cap.isOpened() and g_exit == False):
        ret, frame = cap.read()
        if ret == True:
            frame = cv2.flip(frame, 1)
            # 将图像的通道顺序由BGR转换成RGB
            frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
            if isinstance(frame, np.ndarray):
                frame = Image.fromarray(frame.astype(np.uint8))

            photo = ImageTk.PhotoImage(image=frame)
            image_cvs.create_image([320, 240], image=photo)

            win.update_idletasks()
            win.update()
    cap.release()
    win.quit()

if __name__ == '__main__':
    win = tk.Tk()
    image_cvs = tk.Canvas(win, width=640, height=480, bg='white')
    image_cvs.pack()

    # 点击界面右上角的关闭按钮时，会触发'WM_DELETE_WINDOW'消息
    # 我们在此截获该消息，并改变其行为
    win.protocol('WM_DELETE_WINDOW', close_window)

    win.after(200, video_show)
    win.mainloop()

 在使用Canvas显式图片时，其image参数有两个重要的点需要注意，一个是格式，另外一个是要保持持续引用（可使用全局变量）。如下：

• The image object should be a PhotoImage or BitmapImage, or a compatible object (such as the PIL PhotoImage).
• The application must keep a reference to the image object.