使用实时摄像机预览更新matplotlib中的帧

使用实时摄像机预览更新matplotlib中的帧 互动模式

在matplotlib中更新图的一种方法是使用交互模式（

plt.ion()

）。然后，您不应为捕获的每个帧重新创建新的子图，而应使用图像创建一次绘图，然后再进行更新。

import cv2import matplotlib.pyplot as pltdef grab_frame(cap):    ret,frame = cap.read()    return cv2.cvtColor(frame,cv2.COLOR_BGR2RGB)#Initiate the two camerascap1 = cv2.VideoCapture(0)cap2 = cv2.VideoCapture(1)#create two subplotsax1 = plt.subplot(1,2,1)ax2 = plt.subplot(1,2,2)#create two image plotsim1 = ax1.imshow(grab_frame(cap1))im2 = ax2.imshow(grab_frame(cap2))plt.ion()while True:    im1.set_data(grab_frame(cap1))    im2.set_data(grab_frame(cap2))    plt.pause(0.2)plt.ioff() # due to infinite loop, this gets never called.plt.show()

功能动画

当然，另一种选择是使用matplotlib的内置功能，

FuncAnimation

该内置功能专门设计用于对图进行动画处理。

import cv2import matplotlib.pyplot as pltfrom matplotlib.animation import FuncAnimationdef grab_frame(cap):    ret,frame = cap.read()    return cv2.cvtColor(frame,cv2.COLOR_BGR2RGB)#Initiate the two camerascap1 = cv2.VideoCapture(0)cap2 = cv2.VideoCapture(1)#create two subplotsax1 = plt.subplot(1,2,1)ax2 = plt.subplot(1,2,2)#create two image plotsim1 = ax1.imshow(grab_frame(cap1))im2 = ax2.imshow(grab_frame(cap2))def update(i):    im1.set_data(grab_frame(cap1))    im2.set_data(grab_frame(cap2))ani = FuncAnimation(plt.gcf(), update, interval=200)plt.show()

为了在按键事件时关闭窗口，您可以像这样添加回调

#... other preani = FuncAnimation(plt.gcf(), update, interval=200)def close(event):    if event.key == 'q':        plt.close(event.canvas.figure)cid = plt.gcf().canvas.mpl_connect("key_press_event", close)plt.show()# pre that should be executed after window is closed.