import scipy as sp
import matplotlib.pylab as plt
import cv2
import numpy as np

img1 = cv2.imread('bg.jpg')
img2 = cv2.imread('sun1.jpg')

rows,cols,channels = img1.shape
roi = img2[0:rows, 0:cols ]

dst = cv2.addWeighted(img1,0.5,roi,0.5,0)

#cv2.imshow('win',dst)

cv2.waitKey(0)


def nothing(x):
    pass

cv2.namedWindow('win')
cv2.createTrackbar('opacity','win',0,10,nothing)

while(1):
    cv2.imshow('win',dst)
    k = cv2.waitKey(1) & 0xFF
    if k == 27:
        break
        # get current positions of four trackbars
    r = cv2.getTrackbarPos('opacity','win')
    dst = cv2.addWeighted(img1,r/10.0,roi,1-(r/10.0),0)

cv2.destroyAllWindows()