numberOfPyramids = 9

# generate Gaussian pyramids for A and B Images
GA = A.copy()
GB = B.copy()
gpA = [GA]
gpB = [GB]

for i in xrange(numberOfPyramids):
    GA = cv2.pyrDown(GA)
    GB = cv2.pyrDown(GB)
    gpA.append(GA)
    gpB.append(GB)

# generate Laplacian Pyramids for A and B Images
lpA = [gpA[numberOfPyramids - 1]]
lpB = [gpB[numberOfPyramids - 1]]

for i in xrange(numberOfPyramids - 1, 0, -1):
    geA = cv2.pyrUp(gpA[i], dstsize = np.shape(gpA[i-1])[:2])
    geB = cv2.pyrUp(gpB[i], dstsize = np.shape(gpB[i-1])[:2])

    laplacianA = gpA[i - 1] - geA if i != 1 else cv2.subtract(gpA[i-1], geA)
    laplacianB = gpB[i - 1] - geB if i != 1 else cv2.subtract(gpB[i-1], geB)

    lpA.append(laplacianA)
    lpB.append(laplacianB)

# Now add left and right halves of images in each level
LS = []
for la, lb in zip(lpA, lpB):
    _, cols, _ = la.shape
    ls = np.hstack((la[:, : cols / 2], lb[:, cols / 2 :]))
    LS.append(ls)

# now reconstruct
ls_ = LS[0]
for i in xrange(1, numberOfPyramids):
    ls_ = cv2.pyrUp(ls_, dstsize = np.shape(LS[i])[:2])
    ls_ = ls_ + LS[i] if i != numberOfPyramids - 1 else cv2.add(ls_, LS[i])

cv2.imshow(namedWindowName, ls_)
cv2.waitKey()