为什么我这个程序实现不了渐变呢？

Question

'''
Created on 2015-9-16

@author: PC
'''
import cv2
from matplotlib import  pyplot as plt
import time
img1=cv2.imread("D:\\a1.jpg")
img2=cv2.imread("D:\\a2.jpg")
b=1.0
a=0.0
while 1:
    if a<=1.0: 
        img=cv2.addWeighted(img1,a,img2,b,0)
        cv2.imshow("jianbian",img)
        time.sleep(5)
        print a,b
        a=a+0.1
        b=b-0.1
    else:
        print "ok,that finish "

       
    
    cv2.waitKey(0)
    break
   
cv2.destroyAllWindows()

Answer 1

cv2.waitkey(记得要有数字)不要是0就行了