树莓派用Python中的OpenCV来表示USB摄像头画面

确认Python版本

$ python
Python 2.7.13 (default, Jan 19 2019, 14:48:08) 
[GCC 6.3.0 20170124] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> quit()

确认OS版本

$ uname -a
Linux raspberrypi 3.18.11-v7+ #781 SMP PREEMPT Tue Apr 21 18:07:59 BST 2015 armv7l GNU/Linux
$ lsb_release -a
No LSB modules are available.
Distributor ID: Raspbian
Description:    Raspbian GNU/Linux 9.1 (stretch)
Release:        9.1

安装OpenCV和Python版的OpenCV安装包

$ sudo apt-get install libopencv-dev
$ sudo apt-get install python-opencv

Python的例程

import cv2
#初期化USB摄像头
cap = cv2.VideoCapture(0)
while( cap.isOpened() ):
	#USB摄像头工作时,读取一帧图像
    ret, frame = cap.read()
    #显示图像窗口在树莓派的屏幕上
    cv2.imshow('Capture',frame)
    #按下q键退出
    key = cv2.waitKey(1)
    #print( '%08X' % (key&0xFFFFFFFF) )
    if key & 0x00FF  == ord('q'):
        break
# 释放资源和关闭窗口
cap.release()
cv2.destroyAllWindows()

图像输出的树莓派截屏