Openv-python学习2--图片灰度变换

import cv2   
import numpy as np 

img = cv2.imread("beauty.jpg")   
emptyImage = np.zeros(img.shape, np.uint8) 
emptyImage2 = img.copy()
emptyImage3=cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)  
cv2.namedWindow("Image")   
cv2.imshow("Image", emptyImage2) 
cv2.imshow("EmptyImage", emptyImage)  
cv2.imshow("Image", img)  
cv2.imshow("EmptyImage2", emptyImage2)  
cv2.imshow("EmptyImage3", emptyImage3)  
cv2.imwrite("./cat2.jpg", img, [int(cv2.IMWRITE_JPEG_QUALITY), 5])  
cv2.imwrite("./cat3.jpg", img, [int(cv2.IMWRITE_JPEG_QUALITY), 100])  
cv2.imwrite("./cat.png", img, [int(cv2.IMWRITE_PNG_COMPRESSION), 0])  
cv2.imwrite("./cat2.png", img, [int(cv2.IMWRITE_PNG_COMPRESSION), 9])  
cv2.waitKey (0)  
cv2.destroyAllWindows()