Python-openCV RGBチャネル図を読む

#coding=utf-8
'''openCV        Mat，  matrix       ，      opencv2\core\core.hpp ，           ，C++   
Python  numpy， Python      Mat'''
#openCV        （h,w,channel）,   BGR
import cv2
import  sys
if __name__=='__main__':
    if len(sys.argv)>1:
        img=cv2.imread(sys.argv[1],cv2.CV_LOAD_IMAGE_UNCHANGED)
        b=img[:, :, 0]
        g=img[:, :, 1]
        r=img[:, :, 2]
        cv2.imshow('img', img)
        cv2.imshow('B',b)
        cv2.imshow('G', g)
        cv2.imshow('R', r)
        cv2.waitKey(0)
        cv2.destroyAllWindows()
    else:
        print 'can not open the image'


  ：:~/PycharmProjects/OpenCV$ python show_RGB.py timg.jpeg